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Atlantic Shield Tectonics, Geology, Metallogeny - Sao Francisco Craton, Goias Massif, Tocantins, Borberema and Mantiqueira Provinces, Araguaia, Paraguaia, Brasilia, Aracuai and Ribeira, Orogens, Quadrilatero Ferrifero, Transbrasiliano Lineament

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Atlantic Shield Tectonics, Geology Metallogeny

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Tocantins Tectonics, Geology Mineral Deposits

SUMMARY

The Atlantic Shield is centred on the São Francisco Craton, which includes the oldest rocks known in South America, and prior to the separation of South America and Africa during the Cretaceous, was part of the greater São Francisco-Congo cratonic block. The São Francisco Craton is bounded by three composite, principally Neoproterozoic, orogenic belts, the Borborema Province to the north, the Tocantins Province to the west and southwest, and the Mantiqueira Province to the southeast. To the east, the craton is cut by the Atlantic coastline marking its separation from Africa during the Cretaceous. The shield is partially covered by two large, Phanerozoic, intracratonic sedimentary provinces i). the Parnaíba Basin to the north, which overlies the concealed cratonic Parnaíba Block that is separated from the São Francisco Craton by orogenic belts belonging to the Borborema Province, and is bounded to the west by the Araguaia Fold Belt of the Tocantins Province; and ii). the Paraná Basin to the south, which similarly overlies the concealed cratonic Paranápanema Block that is separated from the São Francisco Craton to its NE by the Brasilia Belt, and to the NW by the Paraguaia Belt, both of which are part of the Tocantins Province. To the west, the Atlantic Shield is separated from the Amazonian Craton by the Araguaia and Paraguaia fold belts of the Tocantins Province to the north and south respectively.
The São Francisco Craton has an ancient Eoarchaean to Palaeoarchaean core of tonalitic-trondhjemitic-granodioritic (TTG) orthogneisses, the Gavião Block. The reworked Palaeoarchaean rocks of the Porteirinha Block, marginal to the craton in the Neoarchaean Araçuai Belt, is a southern extension of that ancient core. Some Palaeoarchaean gneisses are also mapped in the Quadrilátero Ferrífero Block in the south of the craton. These older orthogneisses are accompanied by Palaeoarchaean meta-volcano-sedimentary sequences (e.g., the Jacobina Group) towards the eastern margin of the Gavião Block. A number of Mesoarchaean blocks adjoin the Palaeoarchaean core, mainly granite-gneiss complexes and greenstone belts. They include much of the Quadrilátero Ferrífero Block; its northeastern continuation, the Guanhães Block in the Araçuai Belt; as well as within the Gavião Block and the Serrinha Block (SB) to the NE of the latter.
In the Quadrilátero Ferrífero Block of the southern São Francisco Craton, tectonic activity and magmatism continued from the Meso- into Neoarchaean, with significant accretion of juvenile crust representing the Rio das Velhas orogenic cycle. This cycle was responsible for the Rio das Velhas Greenstone Belt and its principal member, the Rio das Velhas Supergroup. This suite of greenstones and sedimentary rocks, which include banded iron formations, host important gold deposits within the Quadrilatero Ferrifero Gold District. Coeval and substantial accretion of Neoarchaen crust also took place during the Jequié orogenic cycle in the northeastern arm of the craton, particularly in the Jequié Block, and as the NNW-SSE oriented, open 'S-shaped' composite Itabuna-Salvador-Curaçá Belt wrapping around the Serrinha Block to the NE and the Jequié Block to the SW. Together these strongly deformed and metamorphosed tectonic elements separate the Gavião and Serrinha blocks. Another significant Neoarchaean sequence was that of the Mundo Novo Greenstone Belt further to the west, within the eastern margin of the Gavião Block where it is structurally interleaved with Palaeoarchaean sequences, including the Jacobina Group, along the long-lived Contendas-Mirante-Jacobina Lineament. The Rio das Velhas and Jequié orogenic cycles reflect the amalgamation of Meso- and older Palaeo- to Eoarchaean blocks to form the São Francisco protocraton from 2.77 Ga onwards. During this period, the neighbouring Borborema Province to the north, which also contains Eo- to Palaeoarchaean nuclei was similarly part of the protocraton and remained so until it was dismembered during the late Neoproterozoic Braziliano Event.
The Neoarchaean compressional event was succeeded by tectonic relaxation and then widespread continental rifting and deposition of extensive shelf and passive margin volcano-sedimentary sequences, particularly the up to ~6000 m thick Minas Supergroup that includes economically significant silicic and dolomitic banded iron formation. Between 2.47 and 2.13 Ga, roughly coeval with the passive margin sequence, an extended episode of juvenile magmatism took place to the south as the Mineiro Belt. This is interpreted as an intra-oceanic accretionary orogen above a south dipping subduction zone that consumed the oceanic crust that was the substrate of the distal Minas Basin to the north. Subsequent collision and obduction/imbrication of the Mineiro Belt arc over the passive margin of the southern Quadriláátero Ferrífero, led to the inversion of the Minas Basin and the Transamazonian Orogeny/Event. This occurred in at least two main phases from ~2.25 to 2.10 and ~2.06 to 2.00 Ga during the Rhyacian and Orosirian periods of the Palaeoproterozoic. This renewed compressional activity resulted in widespread metamorphism and reworking to granulitic facies and migmatites and the development of voluminous Rhyacian to Orosirian granitoids and syenites, both within the São Francisco Craton and marginal to it. The early Palaeoproterozoic extensional sequence and inversion and magmatism is represented across the craton in the Quadrilátero Ferrífero Block; the Saúde Complex and Contendas-Mirante volcano-sedimentary belt (CMB), which occur in a tight synform pinched between the Gavião and Jequié blocks; the Colomi Group on the northern margin of the Gavião Block; other supracrustal belts occur as outliers and in-folded keels over the eastern Gavião Block progressively to the west from the Contendas-Mirante Belt (CMB) and are interpreted to mostly be of Palaeoproterozoic age. These may be remnants of an extensive Palaeoproterozoic coverage of the Gavião Block deposited in the postulated Caraíba-Juazeiro-Ipirá-Contendas Sea which also spread east over the Itabuna-Salvador-Curaçá Belt reflected by similar infolded remnants. Further to the NE, the equivalent Rio Itapicuru Greenstone Belt (RIGB), and its more restricted, interconnected neighbour to the east, the Rio Capim Greenstone Belt (not named on image), are both infolded into the underlying Mesoarchaean Serrinha Block (SB). Further still to the east, across the intervening Cretaceous Recôncavo-Tucano rift basin (RTB), a NNE-SSW elongated strip of similar rocks is exposed just west of the Atlantic coast in the form of the Early Palaeproterozoic Salvador-Esplanada-Boquim Belt (SEBB).
The Rhyacian-Orosirian Transamazonian orogenic cycle was followed by a long period of extensional tectonics that began between 2.05 and 2.08 Ga in the Orosirian and persisted, through a number of pulses, until the lowermost Neoproterozoic. This extension was centred on the NNW-SSE elongated Paramirim Aulacogen which divides the São Francisco Craton into northeastern and southern segments. The principal succession deposited through this period was the thick intracontinental Espinhaço Supergroup. A similar intracratonic succession belonging to the same supergroup is found to the south in the Southern Espinhaço Domain which straddles the eastern thrust boundary between the Neoproterozoic Araçuaí Belt and the São Francisco Craton.
The final pulse of the long lived multi-stage extension corresponded to the onset of Neoproterozoic deposition over the São Francisco Craton, comprising the São Francisco Supergroup from ~974 Ma. This supergroup was composed of a rift sequence that graded upwards into the sag phase Irecê and São Francisco Basins between 874 and 761 Ma in the Tonian and Cryogenian. These sag phase basins hosted the extensive, but relatively thin Bambuí Group carbonate dominated sequence that covered much of the craton, interfingering with the surrounding thick sedimentary packages deposited in marginal marine basins. During the latest Neoproterozoic Ediacaran, the gradual convergence of the surrounding cratonic blocks led to the overthrusting of the marginal basin sequences and their imbrication onto the margins of the craton, accompanied by the generation of gneisses, migmatites and anatectic granites. The associated uplift contributed clastic detritus to the intracontinental basins developed on the craton.
The São Francisco Craton is bounded to the SE by the Araçuaí Orogen/Fold Belt of the Mantiqueira Province. This fold belt lay between the São Francisco and West Congo cratons prior to the separation of Africa from South America in the Mesozoic. It began as a Neoproterozoic extensional basin which opened 'scissor-like', with the two cratons joined/hinged to the north, but diverging to form a gulf open to the south separating them. Deposition of rift-sag facies and then deeper turbidite on cratonic basement occurred on cratonic basement during the Tonian and to ~660 Ma in the Cryogenian when extension had advanced, with crustal attenuation giving way to the emplacement of oceanic crust. At ~630 Ma, the extensional sequence began to be inverted, with contraction being accommodated by eastward dipping subduction of the newly formed oceanic crust in the south below the Congo Craton and forming the major volcano-plutonic Rio Doce Magmatic Arc on the western edge of the latter. This advance mirrored the extension, hinged in the north and most intense to the south. In addition to the arc, a high grade metamorphic crystalline core was generated to the east of the arc. This compressive regime culminated in the emplacement of extensive Ediacaran granitic batholiths and smaller stocks, followed by late to post-collisional granites between 560 and 535 Ma, and post-collisional tectonic collapse between 520 and 490 Ma. It also resulted in thin-skinned deformation to the west imbricating and thrusting both basinal sequences and basement slabs onto the margin of the São Francisco craton.
The Araçuaí Belt passes directly into the Ribeira Belt to the SW. Both are part of the greater NE-SW to ENE-WSW trending Mantiqueira Province as discussed above. The evolution of the Ribeira Belt has been interpreted to represent the progressive accretion of i). an inner late Cryogenian to Ediacaran (650 to 595 Ma) and ii). an outer two pulse Tonian to Ediacaran 859 to 607 Ma) magmatic arc systems. The inner arc system was thrust onto the the Mineiro Belt and southeastern and southern passive margin of the São Francisco Palaeocontinent during the Neoproterozoic. The inner arc represents the southwestern continuation of the Rio Doce arc of the Araçuaí Fold Belt
The Borborema Province is bounded to the west by the Parnaíba Basin and concealed cratonic Parnaíba Block, while it defines the northern margin of the São Francisco Craton. It is a complex mosaic of Palaeoarchaean to early Mesoproterozoic basement fragments/domains and Neoproterozoic fold belts, separated by major regional shear zones. The Borborema Province had undergone consolidation during the Rhyacian orogenesis, along with the São Francisco Craton, and until at least the Cryogenian in the mid-Neoproterozoic had largely remained united with the craton. In this context, the Borborema Province can be interpreted as a cluster of fragments that were rifted from the São Francisco Craton, reworked and then re-accreted during the Brasiliano-Pan African Orogeny between ~640 and 550 Ma. In the latter process, it was split into three major tectonic entities by regional shear zones: the Northern, Transverse and Southern sub-provinces, each of which is further subdivided into internal alternating meta-igneous and meta-sedimentary domains, separated by other shear/fault zones.
The Rio Preto Belt on the northwestern margin of the São Francisco Craton represents submarine slope-apron deposits laid down on the craton margin after 850 Ma, and thrust SW during the 600 to 540 Ma Brasiliano Orogeny to overlie the craton and its Bambuí Group carbonate cover sequence.
The Riacho do Pontal Fold Belt is to the east of the Rio Preto Belt and occupies the full width of the Southern sub-province of the Borborema Province. It represents a progression from passive margin deposition on the northern slope of the São Francisco Craton, followed by rifting, then inversion to a compressive regime, accompanied by subduction with development of a magmatic arc, collision and a south-verging thin-skinned nappe system thrust over the craton margin.
The Sergipano Fold Belt is the eastern continuation of the Riacho do Pontal Fold Belt. With the Pernambuco-Alagoas Terrane (PAT), across the Marancó Shear Zone (MSZ) to its north, the two domains constitutes the eastern section of the Southern Sub-province of the Borborema Province. As such the two domains are very similar in setting and lithological assemblage to the Riacho do Pontal Fold Belt as described later in this record accessed via the link above.
Much of the western half of the Atlantic Shield of central Brazil is occupied by the Tocantins Province that was assembled during the Neoproterozoic, Brasiliano-Pan African Orogen. It is wedged between the Amazonian and São Francisco cratons to the NW and SE respectively, the concealed Parnaíba Block to the NE, the Paranápanema Block to the south, and the Rio Apa Block to the SW, and is comprises the following orogens, domains and terranes:
Goiás Massif, an ~700 x 75 to 200 km, NE-SW elongated core to the province, composed of an uplifted, structurally juxtaposed collage of Archaean to Palaeoproterozoic basement terranes. It is composed of four main terranes, all of which lie between the underlying Rio dos Bois and overlying Rio Maranhão thrusts, both of which are SE vergent. They are, from SW to NE:
• Crixás-Goiás Terrane - composed of ~70% Mesoarchean to Early Neoarchean TTG complexes, and five elongate greenstone belts that occur as synformal keels. Three of these are of Mesoarchaean age, while the two towards the eastern margin of the terrane are of Rhyacian age in the Palaeoproterozoic.
• Campinorte Terrane - much of which is composed of Upper Rhyacian 2.19 to 2.07 Ga juvenile metavolcano-sedimentary rocks of the Campinorte Sequence, also described as the Paleoproterozoic Campinorte Arc. In the north, it is cut by the 1658 to 1574 Ma Serra da Mesa Suite A-type Mesoproterozoic granites, interpreted to represent regional intracontinental magmatism, related to regional extension within the Goiás Massif. This same extensional event was accompanied by deposition of the 1600 to 1470 Ma Serra da Mesa Group metasedimentary succession which unconformably overlie and almost entirely mask the Campinorte Sequence. A string of three major layered, 800 and 770 Ma, mafic-ultramafic complexes, from SW to NE, the Barro Alto, Niquelândia and Cana Brava intrusions, are aligned over a 350 km interval along the southeastern margin of the Campinorte Terrane, immediately NW of the SE vergent Rio Maranhão thrust that defines the SE margin of the terrane. The three complexes have intrusive contacts on their western margins with metamorphosed volcano-sedimentary successions. The metavolcanic rocks of these latter sequences have E-MORB and N-MORB geochemical affinities, and have been dated as Mesoproterozoic, 1.30 to 1.26 Ga. They occur as a band between the mafic-ultramafic complexes and the older Serra da Mesa continental rift sedimentary succession.
• Cavalcante-Arraias Terrane, is predominantly composed of peraluminous metagranitoids of the Paleoproterozoic Aurumina Suite, which intrude biotite-garnet paragneiss, migmatite and mica-graphite schist of the Rhyacian Ticunzal Formation. These were eroded and covered by the rift-related, predominantly sedimentary rocks of the late Palaeo- to Mesoproterozoic, 1.7 to 1.5 Ga, Araí Group, that include rhyolitic volcanic rocks dated at 1771 Ma. This group temporally overlaps similar rift related sequences of the Serra da Mesa Group of the Campinorte Terrane to the NW and the Espinhaço Supergroup of the São Francisco Craton to the east, and is similarly intruded by granitoids related to the 1658 and 1574 Ma Mesoproterozoic A-type granites of the Serra da Mesa Suite of the Campinorte Terrane.
• Almas-Conceição do Tocantins Terrane, defined by a network of folded narrow, up to 4 km wide, greenstone belt keels, surrounded by Palaeoproterozoic gneissic TTG complex domes. The minimum age of the greenstones, which include basalt, phyllite, banded iron formation, quartzite, chert and felsic meta-volcanic rocks, is indicated by its xenoliths within ~2.45 Ga granitoids. A progression of granitoids that range from 2.45 to 2.18 Ga are intruded into the terrane followed by the ~2.17 Ga metavolcano-sedimentary Água Suja Group which straddles the boundary with the Cavalcante-Arraias Terrane, as does a series of 2.18 to 2.14 Ga metagranitoids that are correlated with the Aurumina Suite that constitutes the bulk of the neighbouring Cavalcante-Arraias Terrane. The northwestern quadrant of the terrane is covered by an extensive ~1.8 Ga intracontinental sag-type basin containing the Late Palaeoproterozoic to Mesoproterozoic Natividade Group.
The Early Neoproterozoic Goiás Magmatic Arc, was emplaced on the outer western and southwestern margins of the São Francisco palaeocontinent, which by the late Mesoproterozoic included the accreted Goiás Massif. The arc is divided into the NNE-SSW elongated Mara Rosa Arc, and the NNW-SSE trending Arenópolis Arc. Both arcs were initiated some time after ~1.2 Ga, located above intra-oceanic subduction zones that were outward dipping beneath the Amazonian Craton and the cratonic Paranápanema Block to the west and SW respectively. Both advanced towards the passive margins of the São Francisco Craton until ~800 Ma when the Mara Rosa Arc collided with and overthrust the Goiás Massif. This resulted in imbrication and crustal thickening of the latter, producing a high temperature metamorphic assemblage, migmatisation and anatexis. Tectonic relaxation, slab-break-off, delamination and detachment of the subcrustal lithospheric mantle (SCLM) followed. Detachment of the denser SCLM was accompanied by concomitant uplift of the crust, asthenospheric upwelling and its decompression melting. This led to the emplacement of the 800 to 770 Ma Barro Alto, Niquelândia and Cana Brava layered mafic complexes in the Goiás Massif, guided by the active Rio Maranhão Thrust below the leading edge of the overthrust arc. This tectonic pause was followed by the renewed advance of the Arenópolis Arc towards the Brasilia Belt shelf sequence on the São Francisco palaeocontinent passive margin. This tectonic activity also led to oblique contraction of the Mara Rosa Arc and Goiá Massif and reactivation of the major structures along the base of the Barro Alto, Niquelândia and Cana Brava layered mafic complexes. Magmatism persisted on the reactivated Arenópolis Arc, generating 790 and 786 Ma granitoids, until collision at ~750 Ma, followed by imbrication, as the Brasilia Belt passive margin was thrust below the advancing Arenópolis Arc until ~630 Ma. This produced 670 to 630 Ma continental arc magmatism, when the degree of imbrication and crustal thickening were sufficient to promote anatexis and high pressure and temperature metamorphism. Compression and thickening were followed by compensatory tectonic relaxation, rebound and a subsequent phase of extension that lasted from ~630 to 540 Ma, resulting in crustal attenuation, uplift, asthenospheric upwelling, anatexis, voluminous bimodal granitoids and eventually the exposure of previously deeply buried high temperature metamorphic suites.
The Brasilia Fold Belt is exposed over a >1000 km long, NNW elongated, north-tapering, wedge-shaped belt. It lies to the west of the São Francisco Craton and to the east of the Goiás Massif, bounded to the SW by the Arenópolis Arc and the overlying Paraná Basin. It overlies Archaean to Palaeoproterozoic basement and has been subjected to east vergent Neoproterozoic compressional such that the contacts with the Goiás Massif, Arenópolis Arc, São Francisco Craton and individual units/domains within the belt are all marked by west dipping thrusts. The principal stratigraphic units of the Brasilia Belt are as follows:
Paranoá Group, which occupies the northern end of the easternmost structurally bounded domain of the Fold Belt. It comprises a mature siliciclastic sedimentary pile that commences with a basal paraconglomerate, followed by transgressive and regressive siliciclastic cycles that include thick quartzite layers, with intercalations of meta-siltstone and minor lenses of limestone and dolostone, culminating at the top with pelites and stromatolitic dolostones. It is estimated to have been deposited within the age bracket of 1170 to 950 Ma and is structurally overlain to the NW by older rocks of the Goiá Massif and is, in turn, thrust over the younger Bambuí Group shelf carbonates to the east.
Canastra Group, interpreted to be a temporal equivalent of the structurally overlying Paranoá Group to the north. It occupies much of the eastern Brasilia Belt and comprises a coarsening upward, regressive, rift basin to passive margin platformal association. It progresses upward from chlorite-rich, laminated calc-phyllites with intercalations of light grey calc-schists → pyrite-bearing black carbonaceous to graphitic phyllites and sericitic phyllite with thin quartzite interbeds → turbiditic intercalations of quartzite and phyllite shallow platformal quartzite. It has been subjected to greenschist facies metamorphism, increasing in grade to the south into the interpreted equivalent amphibolite to granulite facies Andrelândia Group. To the east, it is thrust over the laterally equivalent carbonates of the Vazante Group and the younger Bambuí Group, whilst to the west it is overthrust by the temporally equivalent Araxá and Ibiá groups.
Vazante Group, a pelitic to dolomitic shallow marine platformal sequence that forms an ~300 km long belt, structurally overlying the younger Bambuí Group to the east, and overlain across an east-vergent thrust by the Canastra and Ibiá groups to the west. The sequence is interpreted to have been deposited in the sag phase of a cratonic margin rift basin, grading to a passive margin to the east of the Canastra Group. It is estimated to have been deposited between ~1304 and ~935 Ma.
Serra da Mesa Group - is extensively developed, but is restricted to the Campinorte Terrane of the Goiás Massif. It is composed of quartzites, micaceous schists and marbles. It has been described as a possible western equivalent of the Brasilia Belt sequence, although it is now considered to have been deposited between 1600 to 1470 Ma, and as such is most likely older than the Paranoá-Canastra-Vazante groups. The Palaeo- to Mesoproterozoic Araí Group, to the NNE was probably deposited in the same regional rift basin as the Serra da Mesa Group.
Deposition of the Paranoá, Canastra and Vazante groups, and sections of the Andrelândia Group to the south, appear to have occurred in the Paranoá Rift Basin towards the western margin of the São Francisco palaeocontinent, and likely represents a reactivation and eastward migration of the older, initially Palaeo- to Mesoproterozoic Araí Rift Basin that hosts the Araí and Serra da Mesa groups exposed to the west on the Goiás Massif.
Andrelândia Group - mapped in the southwestern extremity of the Brasília Orogen, with a northward gradation into the Canastra-Vazante and younger Araxá groups. It has been subjected to the complex superposition of the collision between the São Francisco palaeocontinent and the Arenópolis Arc, ahead of the cratonic Paranápanema Block, from the SW at ~750 Ma, and the combined Ribeira Belt Inner and Outer arcs from the SSE at ~650 Ma. As a consequence it has been more strongly deformed into a series of imbricated thrust sheets and nappes, more intensely metamorphosed and intruded by granitoids. It includes structurally interleaved slices of Palaeoproterozoic basement, parautochthonous Meso- to Neoproterozoic passive margin sequences belonging to the São Francisco palaeocontinent, as well as allochthonous arc and forearc volcanosedimentary rocks deposited on the oceanic crust in advance of the approaching Paranápanema Block.
Ibiá Group - unconformably overlies the Canastra Group to the east, and structurally overlies the Araxá Group to the west. It comprises a lower, up to 100 m, thick meta-paraconglomerate/diamictite overlain by a thick succession of deep water facies sedimentary rocks metamorphosed to chlorite-muscovite schist, calc-schists and calc-phyllites with fine layers of quartzite.
Araxá Group - which forms an ~700 km long, NNW trending belt, that separates the Goiás Magmatic Arc to the SW and NW, from the passive margin meta-sedimentary units of the Paranoá Basin to the east. The intervening Ibiá Group thrust sheet represents a transitional sequence intermediate between the passive margin and the Araxá Group which is composed of strongly metamorphosed marine deep-water metasedimentary protoliths with associated chert layers and widespread metamafic volcanic and ultramafic rocks. These rocks are interpreted to be distal to the margin of the São Francisco Craton, but more proximal to the Arenópolis Arc. They have been metamorphosed to micaceous quartzite and mica-schists, with a few paragneiss and marble units and widespread amphibolites. The amphibolites are interpreted to include tectonically emplaced ocean floor that locally forms an ophiolitic mélange. The sequence has been imbricated into numerous low angle, east-vergent, thrust sheets internal and marginal to its exposure.
The Araxá Group belt encloses a 10 to 75 km wide, by near 600 km long, thrust bound core of orthogneisses and granulites. This core is, in turn, structurally divided into sheets of gneiss that include both Mesoproterozoic age rocks, possibly Goiás Massif basement, and Neoproterozoic (Cryogenian) orthogneisses representing bimodal continental magmatism on the margin of the São Francisco palaeocontinent, with intercalated chemical and clastic meta-sedimentary rocks. Both the metamorphic core and flanking Araxá Group are intruded by numerous granite plutons in three episodes, an early 833 Ma 'within-plate' event; a ~790 Ma pre-collisional Complex; and a final 642 and 630 Ma suite of mainly peraluminous granites.
Bambuí Group - a thick, Ediacaran, Neoproterozoic succession that is younger than ~640 Ma and is composed of a basal Sturtian glacial diamictite, overlain by carbonate and siliciclastic units generated by three transgressive-regressive cycles in a shallow epicontinental sea. It was largely deposited over the São Francisco Craton, but also laps onto the Paranoá Basin passive margin/platform of the Brasília Belt to the west, where it has subsequently been overthrust by those older rocks.
The Transbrasiliano Lineament originally formed during the late Neoproterozoic final episode of the Brasiliano-Pan African Orogeny between 580 and 550 Ma, but has been reactivated in a further three events during the Phanerozoic. It is an up to 100 km wide, continental-scale discontinuity that separates: i). the pre-Tonian (pre-Neoproterozoic) Amazonian Craton domain to the west, including the Parnaíba Block and the São Luis Craton to the NW, and the Rio Apa Craton to the SW, from ii). the São Francisco and the Paranápanema cratonic blocks and a series of cratonic fragments, magmatic arcs, allochthonous blocks and Neoproterozoic mobile belts that constitute the São Francisco/Brasiliano domain, in the eastern portion of the South American Shield.
The Araguaia Fold Belt represents the northern equivalent of the Brasilia Belt, across the Transbrasiliano Lineament. It is developed along the eastern margin of the Amazonian Craton, whilst the northern two third lies to the west of the cratonic Parnaíba Block. The southern third of the belt is bounded to the east by the Goiás Massif, which by the Mesoproterozoic was accreted onto the São Francisco Craton. To the SW it passes into the Paraguaia Fold Belt which follows the southern and southeastern margin of the Amazonian Craton.
The principal lithostratigraphic unit of the Araguaia Belt is the Baixo Araguaia Supergroup, subdivided into the Neoproterozoic Tocantins Group in the western, or Outer Zone, immediately to the east of the Amazonia Craton, and the more strongly metamorphosed Mesoproterozoic Estrondo Group (est) in the eastern Inner Zone.
The Tocantins Group is further divided into the lower Pequizeiro Formation (peq), exposed in the east of the Outer Zone, structurally juxtaposed against the Inner Zone. It is composed of chlorite schists and chlorite-quartz schist with interbedded calc-shales and metamorphosed mafic to ultramafic complexes; and to the west, the overlying Couto de Magalhães Formation (cdm), which laps onto, and has been thrust over, the Amazonian Craton. This latter formation is predominantly composed of un- to weakly-metamorphosed slate, phyllite, meta-siltstone and meta-claystone with abundant polymictic conglomerate lenses. The predominantly Mesoproterozoic Estrondo Group of the Inner Zone commences with the lower Morro do Campo Formation micaceous quartzite which contains magnetite and kyanite, with interbedded layers of biotite schist and oligomictic meta-conglomerates. The overlying Xambioá Formation includes biotite-muscovite schists with interbedded calc-schists, marbles, meta-greywackes and various schists containing garnet, graphite, staurolite, kyanite and fibrolite. However, while the Morro do Campo Formation is indicated to be of Mesoproterozoic age, the Xambioá Formation contains Neoproterozoic detrital zircons and may be a lateral equivalent of the Tocantins Group.
In the northern half of the Inner Zone, a 250 km long string of 8 metamorphic core complex domes expose ~2.86 Ga Archaean Colméia Complex in their cores. In the southern half of the Inner Zone, the Estrondo Group overlies a much larger area of exposed Archaean to Palaeoproterozoic basement that is bounded to the SE by faults of the Transbrasiliano Lineament. This basement includes the 2.6 Ga Rio do Coco Group greenstone belt type metavolcano-sedimentary sequences; ~2.1 to 2.15 Ga Morro do Aquiles Formation volcano-sedimentary suites; the extensive 2.08 to 2.05 Ga Rio dos Mangues Complex (RDMC) migmatised orthogneisses, calc-silicate gneisses, garnet biotite paragneisses, orthoquartzites, granite-gneisses and subordinate amphibolites; the ~1.861 Ga Serrote Granite; and the late Palaeo- and Mesoproterozoic Monte Santo and Serra da Estrela alkaline gneisses, nepheline syenites and alkali-syenites plutons, dated at 1.70, 1.49 and 1.0 Ga. The 560 to 555 Ma Neoproterozoic Matança Granite intrudes the Transbrasiliano Lineament zone and encroaches onto the southern margin of the Araguaia Fold Belt. The geotectonic history of the Araguaia Fold Belt has involved a number of successive cycles of compression, extension and lateral displacement that are explained in the Araguaia Fold Belt section below.
The Parnaíba Basin covers a generally ellipsoidal area of ~0.6 million km², and comprises up to 3.5 km of mainly post-Ordovician Phanerozoic sedimentary rocks in its depocentre. This sequence overlies a number of late Neoproterozoic to early Palaeozoic rifts developed within the Precambrian crystalline basement. That basement, which is almost entirely concealed, comprises the triangular Parnaíba Block, which is bounded by steep north-south, east-west and SW-NE crustal-scale boundaries that are reflected by abrupt changes in seismic character. This block is assumed to represent Archaean to Palaeoproterozoic intrusive and metamorphic rocks. The structures on its margins have been sporadically active through the Phanerozoic and include the major Transbrasiliano Lineament zone that separates it from the São Francisco Craton and Goiás Massif.
The Paraguaia Fold Belt is largely composed of Neoproterozoic sedimentary rocks deposited during an extensional event, followed by inversion that was characterised by deformation and magmatism, and then by collision between the Amazonian Craton and Paranápanema Block in the north, and the Rio Apa section of the Rio de la Plata Craton from the SW. It grades to the NE into the Araguaia Fold Belt across a relatively narrow neck at the closest separation between the Amazonian and Goiás Massif/São Francisco Craton. To the SW of this neck, it widens as the margin of the Amazonian Craton swings to the west. The sequence in the fold belt is divided into a northern and broadly equivalent southern succession by the extensive, Cenozoic Pantanal Basin. The Northern Paraguaia Fold Belt is divided into a strongly folded and thicker Internal zone to the SE, an open folded, but thrusted External or Pericratonic zone and a Cratonic-platform zone over the Amazonian Craton to the NW. It is occupied by the basal Nova Xavantina felsic meta-volcano-sedimentary sequence; overlain by the Cuiabá Group, which outcrops over a wide area in the southern and eastern portion of the orogen. This latter group is generally composed of organic-rich phyllites and meta-dolostone, overlain by glaciogenic and turbiditic meta-sediments, related to the global 636 Ma Marinoan glaciation event. The diamictites are best developed as the Puga Formation at the top of the group. These are succeeded by the carbonates of the Araras Group - a carbonate unit that has been subdivided into the Guia and overlying Noble formations, composed respectively of bituminous deep ocean shale and limestone, and dolostone. The base of this unit has been dated at 627 ±30 Ma. The upper Araras Group is occupied by the Serra Azul Formation, which is composed of massive diamictite at the base, overlain by a sequence of mudstone, siltstone and sandstone at the top. The diamictite is correlated with the ~580 Ma Gaskiers Glaciation. Exposures of the Araras Group and Puga Formation are largely restricted to the External and Cratonic zones. The uppermost unit is the unconformably overlying Alto Paraguaia Group that is characterised by continental molassic sedimentation.
the Southern Paraguaia Fold Belt comprises, from the base: the Basement Rio Apa Craton which was formed between 1.95 and 1.75 Ga, with interpreted remnant 2.2 to 1.95 Ga oceanic crust, and represents a Late Palaeoproterozoic continental arc, composed of a western banded orthogneisses of the Porto Murtinho Complex, intruded by early phase granitoids of the 1.88 to 1.71 Ga Amoguijá arc. Its central sector contains granites, felsic volcanic rocks of the Serra da Bocaina Formation, the Serra da Alegria gabbro-anorthosite suite, and a gabbro, all overlain by sedimentary rocks. The eastern segment is a backarc basin, intruded by late to post-orogenic and A-type granites of the Rio Apa Complex. All of these are of Palaeoproterozoic age, and are intruded by the 914 ±9 Ma Rio Perdido mafic dykes and sill swarms related to a late extensional event. These are overlain by the Jacadigo Group, which is composed of the basal conglomeratic and sandy braided stream deposits of the Urucum Formation. The overlying Santa Cruz Formation comprises hematite-rich banded iron formation with manganese oxide intercalations and lens of diamictite. The Jacadigo Group, which hosts major iron ore deposits (Corumba-Urucum) is correlated with the Cuiabá Group and the iron formation of the Santa Cruz Formation with the glacial diamictite of the Puga Formation in the Northern Paraguaia Fold Belt. The overlying carbonate-rich Corumbá Group, which is regarded to be equivalent to the Araras Group to the north, is divided into the glacio-marine diamictite of the Cadiueus Formation; the shallow, tidal, shelf-marine facies dark-grey to black sandstones and siltstone of the Cerradinho Formation; the stromatolite-rich dolostone to dolomitic limestone and limestone of the Bocaina Formation; the carbonatic-clastic sequence of the Tamengo Formation and the grey laminated siltstones and finer-grained pelite of the Guiacurus Formation. The uppermost Tamengo and the Guiacurus Formation are correlated with the Alto Paraguaia Group of the Northern Paraguaia Fold Belt.
The Paraná Basin is a Palaeozoic to Late Mesozoic intra-cratonic basin that covers an area of ~1.5 km² in southern Brazil and neighbouring countries, and hosts a large igneous province, the extensive basaltic flood lavas of Cretaceous Serra Geral Formation. It laps onto the Amazonian, São Francisco and Rio Apa cratons. It is overlain to the west by the Cenozoic Pantanal Basin and is underlain by a thick Precambrian basement block, the Paranápanema Block. The latter is separated from the neighbouring cratonic elements by the Paraguaia and Brasilia fold belts to the west and NE respectively, and the Ribeira Belt to the SE. The Paranápanema Block is also separated from the Amazonian and Rio Apa cratonic basement to the NW by the Transbrasiliano Lineament.
The Paranápanema Block has been considered a fragment that separated from either the São Francisco craton during a Tonian rifting event or from the Central African/Congo Craton. It has been interpreted to comprises a Palaeoproterozoic Rhyacian and Statherian continental basement to the Paraná Basin and has the geophysical signature of a cratonic domain with a thin and stable continental crust, coupled to a thick underlying lithospheric keel. Mid Mesoproterozoic Ectasian carbonate and clastic units reflect a passive continental margin along the northeastern to eastern margin of the Paranapanema Block, followed by the establishment of a Neoproterozoic active continental margin and magmatic arc (Arenópolis Arc) along its entire northeastern edge.
Deposition within the Paraná Basin reflects a long-lived stable basement where tectonic activity comprised gentle subsidence and uplift cycles producing transgressive-regressive marine cycles and no significant proximal orogenic activity. Six 'supersequences' were deposited for a maximum 7000 m thick succession between ~660 Ma in the Ordovician to 66 Ma at the top of the Cretaceous, as described in more detail below.
Deposition over the adjacent Amazonian and São Francisco Cratons took place in similar settings, forming the Parecis and São Franciscana basins respectively, whilst in the Paraná Basin, sedimentation retreated in area to become the overlying Bauru Sub-basin in its northern third. These three temporally equivalent cratonic basins represent deposition during a period of extension related to the progressive opening of the South Atlantic Ocean, and are spatially separated by Cretaceous uplifts (Fig. 1). The São Franciscana Basin, which overlies the São Francisco Craton, is composed of the Urucuia Sub-basin in the north, and the dismembered remnants of its southern extension, the Abaeté Sub-basin, the result of uplift and erosion. It is separated from the Bauru Basin to the south by the NW-SE trending Alto Paranaíba Arch, and from the Parecis Basin to the west by the Gloias Massif. Both of these structural features expose Meso- to Neoproterozoic successions. The Bauru Basin is separated from the Parecis Basin to the NW by the Cretaceous Rondonópolis Uplift which exposes Neoproterozoic basement of the Paraguaia Orogen. Magmatism, in the form of the Alto Paranaíba Igneous Province, is developed over the Alto Paranaíba Arch. It comprises multiple intrusions of ultrapotassic to potassic, ultramafic to mafic intrusions, occurring as kamafugites, kimberlite, lamproite, lamprophyre and carbonatites, with temporally equivalent lavas and volcano-sedimentary facies extensively developed within the adjacent São Franciscana Basin.

DISTRIBUTION OF MINERALISATION

A wide range of commodities and ore types are found within the Brazilian Atlantic Shield. The various commodity groupings, distribution, and principal deposits are outlined below, with links to descriptions of individual deposits and deposit clusters, as follows:

GOLD
The distribution of gold or gold-bearing deposits by structural element include:
• the Gavião Block of the eastern São Francisco Craton which contains the Palaeo- to Mesoarchaean or possibly Orosirian (Palaeoproterozoic) conglomerate hosted Jacobina deposits (Fig. 1).
• the Mesoarchaean to Palaeoproterozoic Quadrilátero Ferrífero Block that forms the southern tip of the São Francisco Craton and contains a range of gold deposits (Fig. 1). See also the separate Quadrilatero Ferrifero District Gold - Geological Setting record. These deposits include those hosted by the Nova Lima Group of the Neoarchaean Rio das Velhas Supergroup, within both banded iron formations and in schists/phyllites and gneisses, the more significant of which are: Morro Velho, Raposos, Lamego, Cuiabá, Pilar and Córrego do Sítio, which also includes the previously separate São Bento mine. The Turmalina and São Sebastião mines are part of another cluster of deposits found much further to the NW in the Pitangui Greenstone Belt in rocks broadly correlatable with the Nova Lima Group.
• the Neoarchaean Carajás Province of the Amazonian Craton, separated from the Atlantic Shield by the Araguaia Fold Belt, contains a series of large gold-bearing Iron Oxide Copper Gold deposits, that can be accessed from the aforementioned link. The Serra Pelada gold deposit that has been linked to an IOCG system, is also found within the Carajas district.
• the Neoarchaean Crixás-Goiás Terrane within the Goiás Massif, hosts a cluster of gold deposits that include the Serra Grande mine in the Crixás Mining District (Fig. 2).
• the Palaeoproterozoic Minas Supergroup within the Quadrilátero Ferrífero Block, which unconformably overlies the Neoarchaean Rio das Velhas Supergroup, commences with the basal Moeda Formation that includes the Moeda Conglomerate which hosts gold and uranium mineralisation. No major hypogene deposit has been found within this unit, although it the sources of more recent alluvial accumulations.
• higher within the lower section of the Palaeoproterozoic Minas Supergroup of the São Francisco Craton, mineralisation similar to that of the Neoarchaean Nova Lima Group is found hosted in the Batatal Formation which overlies the Moeda Formation. This is best developed near the upper contact with the overlying banded iron formations of the Itabira Group. This mineralisation is distributed over a 15 km strike length as the Passagem de Mariana deposits.
• further north, in the Palaeoproterozoic (Rhyacian) Rio Itapicuru Greenstone Belt (RIGB; Fig. 1) gold is mined at the Fazenda or Fazenda Brasileiro or Maria Preta deposits.
• the Meso- to early Neoproterozoic Canastra Group of the Brasilia Belt hosts the major Morro do Ouro or Paracatu gold deposit (Fig. 2).
• the Neoproterozoic (Cryogenian) Mara Rosa Arc of the Goiás Magmatic Arc in the Goiáss Massif, hosts the metamorphosed, possibly originally porphyry style mineralisation at the Chapada Cu-Au deposit (Fig. 2);
• shear controlled Cambrian gold mineralisation occurs in the gold province of the western margin Chapada Diamantina Domain (CDD; Fig. 1) within the Paramirim Aulacogen, as veins cutting the Espinhaço Supergroup sedimentary and volcano-sedimentary rocks, with alteration dated at 500 to 497 Ma (e.g., Teixeira et al., 2019). No major deposits are know, with most being garimpos (artisanal workings).

ZINC - LEAD
The principal zinc-lead±copper mineralisation is as follows:
• the Mundo Novo VHMS zinc deposit in the Palaeoarchean Mundo Novo Greenstone Belt of Bahia, ~119 km south of Jacobina. It is composed of as pyrrhotite, sphalerite, pyrite and chalcopyrite with an Indicated Resource of 6 Mt @ 6.2% Zn. The deposit was subsequently intruded by granitoids, deformed and metamorphosed during the Rhyacian convergence.
• the Vazante, Morro Agudo, Ambrosia Sul, Ambrosia Norte, Bonsucesso and Fagundes stratabound to transgressive and carbonate-hosted zinc-lead deposits are hosted within the Meso- to Early Neoproterozoic Vazante; groups of the Brasilia Belt.
• the Boquira lead-zinc deposit, hosted within the Paramirim Block horst which is composed of recessive Palaeoarchaean basement gneisses in the core of the Palaeo- to Mesoproterozoic Paramirim Aulacogen. Mineralisation, which comprises massive lenses of galena, sphalerite and pyrite lenses is interpreted to be either late Neoarchaean or Palaeoproterozoic in age.

COPPER
• the Caraíba and related copper deposits within a Neoarchaean layered orthopyroxenite sill that was reworked during the Rhyacian within the Curaçá terrane, the northern segment of the Neoarchaen Itabuna-Salvador-Curaçá Belt (Fig. 1).
• the Neoproterozoic (Cryogenian) Mara Rosa Arc of the Goiás Magmatic Arc in the Goiás Massif, hosts the metamorphosed, possibly originally porphyry style mineralisation at the Chapada Cu-Au deposit (Fig. 2);

IRON
Iron formations are distributed as follows in the Atlantic Shield and neighbouring Amazonian Craton:
• Early Neoarchaean iron formations are hosted by the Rio das Velhas Supergroup of the Quadrilátero Ferrífero Block that forms the southern tip of the São Francisco Craton. However, although these are hosts major gold deposits, as detailed above, none are of a size or grade to be iron ores. In contrast, the similarly aged banded iron formations/itabirites of the Carajás Province in the neighbouring Amazonian Craton are one of the world's most important sources of iron ore.
• Major latest Neoarchean to early Palaeoproterozoic (Rhyacian) banded iron formations/itabirites are found on the São Francisco Craton. On its southern tip, they belong to the Palaeoproterozoic Minas Supergroup which unconformably overlies the Neoarchaean Rio das Velhas Supergroup and are exploited for iron ore in a large number of major mines of the Quadrilátero Ferrífero Block.
On the northern margin of the same craton, lapping onto the Gavião Block, significant iron ore resources are hosted by the temporally equivalent Colomi Group which is dominated by thick, Early Palaeoproterozoic (Siderian), banded iron formations. This sequence hosts the un-mined (in 2023) Colomi South and Colomi North deposits with JORC compliant Indicated + Inferred Mineral Resources of 1.375 Gt @ 30.9% Fe and 3.602 Gt @ 25.2% Fe respectively for a total of 4.978Gt @ 26.8% Fe as magnetite ore that is capable of upgrading to a high purity 66% Fe magnetite concentrate.
Further Neoarchaean to Palaeoproterozoic (Rhyacian) iron deposits iron ores hosted within interleaved tectonic slices within the Paramirim Aulacogen in south western Bahia near Caetité. The largest deposit is Pedra de Ferro, located 38 km south of Caetité. The mineralised section is between 30 and 120 m wide, primarily composed of compact banded iron formation/itabirite, friable itabirite, and friable hematite. The enclosing sequence is manganese-rich metasedimentary rocks that also carry significant manganese mineralisation, schist, marble, calc-silicates, meta-basalt and meta-andesite. The banded iron formation protore was upgraded to high-grade iron by the sequential removal of silica during the Neoproterozoic to produce both magnetite and hematite ores. Most of the orebodies are structurally controlled by systems of west verging reverse faults, deformed during periods of thrusting and crustal thickening in the Rhyacian (Teixeira et al., 2010). The operator, BAMIN (Bahia Mineração Limitada), a subsidiary of Eurasian Resources Group (ERG) quote reserves at 562 Mt @ 42.4% Fe, comprising 181 Mt of hematite ore and 381 Mt of magnetite itabirite in 2023.
• Late Palaeoproterozoic (Orosirian to Stratherian) banded iron formations/itabirites between 1990 16 and 1666 ±32 Ma, that belong to the early extensional stage that immediately preceded deposition of the main Espinhaço Supergroup. Major mineralisation is found within
i). the iron formations of the Serra da Serpentina Group, preserved along the eastern margin of the Southern Espinhaço Domain (SED). e.g., the major Serra do Sapo mine, and the Itapanhoacanga and Serro deposits of the Minas-Rio Project, and
ii). interleaved allochthonous slivers of iron formation temporally equivalent to the Serra da Serpentina Group, in-faulted into the Mesoarchaean to early Neoarchaean metamorphic rocks of the adjacent Guanhães Block e.g., the relatively small but high grade Horto-Baratinha (27.35 Mt @ 58.92 wt.% Fe) and Cuité deposits (Fig. 1) that are localised either within shear zones or are closely associated with the contact zones of Neoproterozoic pegmatite developments (Silveira Braga et al., 2021).

• Neoproterozoic diamictite hosted iron formations that are found in the Macaúbas Group in the Araçuaí Basin of the Araçuaí Orogen/Fold Belt in northern Minas Gerais, and in the Jacadigo Group of the Paraguaia Fold Belt in Mato Grosso do Sul. For more detail see the Rio Pardo - Rio do Peixe Bravo District and Corumba, Urucum, Santa Cruz records respectively. Whilst some authors equate the two units, finding precise age ranges in the literature has proved elusive, ranging from early Cryogenian in the Araçuaí Belt, to possibly as young as late Ediacaran at Corumba. The deposits at Corumba have vast tonnages of hematite with average grades of 54% Fe enclosing substantial zones of enriched higher grade zones of >60% Fe. Those of the Araçuaí Basin have large tonnages of between 20 and 25% Fe, mostly magnetite, that may be economically upgraded to >60% concentrates.

NICKEL
Both primary sulphide and lateritic nickel deposits are distributed across the Atlantic Shield. Significant Laterite deposits include the Onca and Puma, Vermelho (Fig. 2) deposits of the Carajás district in the neighbouring Amazonian Craton, and the nearby Araguaia North and South deposits (Fig. 2) to the east in the Araguaia Fold Belt.
To the east, on the northern margin of the São Francisco Craton, there is a cluster of probable Palaeoproterozoic (~2.0 Ga) mafic-utramafic and carbonatite intrusions scattered over a 20 km radius area, immediately to the west of the town of Campo Alegre de Lourdes. These intrude Archaean orthogneisses and migmatites of the Sobradinho-Remanso Complex and greenschist facies metasediments of the Palaeo- to Neoproterozoic Serra da Boa Esperança Sequence. One of these, the Caboclo dos Mangueiros Intrusion, hosts a large, but low grade resource of nickel-copper-cobalt mineralisation. Other intrusions on the complex include Fe-Ti-V resources and a carbonatite complex being mined for phosphate (see below). The intrusive cluster is a whole are plotted as the Angico Dos Dias deposit on Fig. 1.
Further south, in the Campinorte Terrane of the Goiás Massif, the Barro Alto and Niquelandia laterite nickel deposits are developed over Neoproterozoic layered complexes (Fig. 2).
Significant sulphide nickel deposits include the Fortaleza de Minas hosted by a Mesoarchaean greenstone belt on the faulted southern margin of the São Francisco Craton (Fig. 2). To the north, in the southern section of the Itabuna-Salvador-Curaçá Belt (Fig. 1) close to its western margin in southeastern Bahia, the Santa Rita Ni, Cu, Co, PGE, PGM sulphide deposit is hosted by the ~2.2 Ga, layered Fazenda Mirabela mafic-ultramafic cumulate intrusion.

IRON TITANIUM VANADIUM
the Neoarchean Maracás-Menchen cluster of vanadium-rich titaniferous magnetite deposits is hosted by the Neoarchaean, largely gabbroic Rio Jacaré Intrusion along the structural contact of the Palaeoproterozoic Contendas-Mirante Belt (CMB) and Neoarchaean Jequié Block.
Significant Fe-Ti-V mineralisation is hosted by two intrusions in the same cluster of probable Palaeoproterozoic (~2.0 Ga) mafic-utramafic and carbonatite intrusions, immediately to the west of the town of Campo Alegre de Lourdes as host the Caboclo dos Mangueiros Ni-Cu-Co mineralisation (see the Nickel section above) and the phosphate bearing Angico dos Dias Carbonatite Complex (see the Carbonatite section below). These intrusions, the Campo Alegre de Lourdes and Peixe mafic-ultramafic complexes, are described in the Caboclo dos Mangueiros, Angico dos Dias record. They lie on the northern margin of the São Francisco Craton and at the same plotted location as the Angico Dos Dias deposit on Fig. 1.

CHROMITE
A number of late Palaeoproterozoic Rhyacian, ~2.1 Ga, mafic-ultramafic intrusives in the north-western São Francisco Craton in Bahia host chromite deposits, including the Jacurici and Campo Formoso complexes and the Santa Luz mafic-ultramafic Complex. All are 175 to 220 km to the NW of Salvador (Fig. 1), and lie within the Serrinha Block which comprises two Mesoarchaean spatially separated suites of migmatitic and granulite facies orthogneisses with a TTG composition.

LITHIUM
The Grota do Cirilo lithium-cesium-tantalum pegmatite deposit cluster lies within the Eastern Brazilian Pegmatite Province that covers an area of ~150 000 km², stretching from the state of Bahia, through Minas Gerais to Rio de Janeiro state. They are hosted within the crystalline core of the Neoproterozoic Araçuaí Fold Belt that separated the São Francisco and Congo cratons.

URANIUM
Examples of uranium deposits in the Atlantic Shield include:
Lagoa Real (Fig. 1), where uranium mineralisation is intimately associated with a string of discontinuous tabular, lenticular albite (±oligoclase) rich bodies ('albitites') exposed over much of the ~100 km long extent of the Lagoa Real granitic-gneiss complex within the Paramirim Block basement. This block forms the core of the northern tongue of the Araçuaí Orogen that encroaches into the São Francisco Craton along the Paramirim Aulacogen. Shear controlled albite alteration has been dated at 1504 ±12 Ma, imposed upon a 1724 ±5 Ma granitic-gneiss of the Lagoa Real Complex. This mineralisation lies below the now largely eroded unconformity with the arenaceous shelf sediments of the Mesoproterozoic Espinhaço Supergroup.
The Santa Quitéria or Itataia phosphate-uranium deposit, which is located within the Borborema Province (Fig. 1) in the State of Ceará in northeastern Brazil. Uranium and phosphate mineralisation are hosted by calc-silicate altered rocks and by less extensive saccharoidal marbles of the Siderian-Rhyacian Early Palaeoproterozoic Caicó Group which is composed of gneisses and carbonate rocks after meta-volcanic, meta-sedimentary and meta-plutonic protholiths. These rocks are poly-deformed and have undergone upper amphibolite to granulite facies metamorphism and extensive migmatisation. Mineralisation is interpreted to be related to a magmatic source and occurs as lenticular lodes that follow the main metamorphic foliation of the host rocks, and as disseminations in the carbonate and migmatitic paragneiss, and lesser crosscutting veins and stockworks.

DIAMONDS
Diamonds have been produced over a wide area within the Atlantic Shield of Brazil. Whilst one primary kimberlite hosted deposit has been mined, the bulk of production has been from recent alluvial accumulations derived from secondary sources. Those secondary sources comprise sedimentary units, usually coarse clastics and conglomerates or diamictites, of Mesoproterozoic, Neoproterozoic, Permo-Carboniferous or Cretaceous age, some of which have grades that are sufficiently high, and/or are strongly weathered and 'soft'. The Upper Cretaceous units, however, contain voluminous lava flows and volcaniclastic units that are temporally and compositionally equivalent to kimberlites intruding the same sequence. More than a thousand kimberlitic intrusions have been found throughout the shield, although only ~20 have been shown to be diamondiferous. These vary in age with individual intrusions or clusters emplaced at ~1152, 640, 235 to 216, ~120 and 98 to 74 Ma. The great majority of diamond production in Brazil has been from artisanal mining, with only a few larger scale operations.
The principal deposits, and diamondiferous provinces/districts within the Atlantic Shield of Brazil are the:
• Northern São Francisco Craton and Diamantina District - which includes the 640 Ma Braúna kimberlite; the 1152 Ma Salvador kimberlite and alluvial deposits of the Chapada Diamantina; the Diamantina District and Duas Barras deposit in the Southern Espinhaço Domain (SED); and the diamondiferous Sopa-Brumadinho and Tombador formations of the Mesoproterozoic Espinhaço Supergroup that are secondary sources of diamonds, but have also locally been mined where sufficiently rich and/or weathered.
• Alto Paranaíba Arch - that hosts the most prolific occurrence of both kimberlitic intrusions and placer diamond mining, covering an area of ~400 x 150 km along axis of the NW-SE trending Lower Cretaceous Alto Paranaíba Arch. This arch is located on the southeastern flank of the Brasilia Belt and São Francisco Craton, opposite the Paranápanema Block (Fig. 1). The province has been divided into 11 'kimberlite fields', the most prolific of which is the Coromandel ‐ Três Ranchos Kimberlite Field which contains >580 'kimberlitic' intrusions. Of these, diamonds have only been recovered from ~18 separate intrusions, although most grades and tonnages are sub-economic. The most significant diamondiferous kimberlites along the arch are the 95 to 82 Ma Catalão and 120 Ma Canastra clusters to the NW and SE respectively (Fig. 2).
The Coromandel alluvial district, which largely corresponds to the Coromandel ‐ Três Ranchos Kimberlite Field, has produced at least 40 million carats of alluvial diamonds in accumulations interpreted to have been derived from Cretaceous secondary sources in the São Franciscana and Paraná basins that flank the arch. Diamonds have been mined directly from the secondary volcano-sedimentary source at the historic Romaria mine. Other smaller alluvial diamonds fields are found along the arch.
• Noroeste do São Francisco Province, located ~100 km east of the Alto Paranaíba Diamond Province. It overlies Mesozoics and Permo-Carboniferous rocks of the São Franciscana Basin and the Neoproterozoic to Cambrian Bambuí Group on the margin of the structurally underlying São Francisco Craton. All three of these cover sequences are potential secondary diamond sources. No 'kimberlitic' intrusions are known within the province.
• Paraguaia Belt exposed in the Rondonópolis Uplift, and the flanking Paraná and Parecis basins, which includes the:
- Chapada dos Guimarães/Quilombo Diamond Province, straddling the external and internal facies of the Paraguaia Belt and the Bauru Sub-basin of the greater Paraná Basin to the south, and is a producer of alluvial diamonds;
- Poxoréu Diamond Province, which is entirely underlain by Cretaceous rocks of the Bauru Sub-basin of the Paraná Basin and also embraces alluvial diamond deposits, without any accompanying diamondiferous kimberlite intrusions;
- Nortelândia-Diamantino Diamond Province, which straddles the external zone of the exposed Paraguaia Fold Belt, and the Parecis Basin to the north, which overlies the Amazonia Craton. This province is extensively mined for alluvial diamonds;
- Paranatinga Diamond Province which also straddles the external zone of the exposed Paraguaia Fold Belt and both the Palaeozoic to Mesozoic Parecis and overlying Cenozoic Alto Xingu basins, all of which overlie the Amazonia Craton. This province also includes Cretaceous diamondiferous kimberlites as well as alluvial diamond accumulations.
• Provinces straddling the Transbrasiliano Lineament, and overlying the Paraná Basin and older basement - the contiguous Rio das Garças and Rio Araguaia diamond provinces are found to the NW and SE of the lineament, respectively. Both host alluvial diamond mines, while the Rio Araguaia Province is intruded by a cluster of barren Cretaceous kimberlites, predominantly downstream of the alluvial diamondiferous alluvial accumulations.
• Kimberlites in the Parnaiba Basin, above the Borborema Province in Piauí, defined by the >40 kimberlitic intrusions of the Moana Diamond Province, one of which is diamondiferous.
For a more detailed description see the Diamond Districts and kimberlites of the Atlantic Shield record.

CARBONATITES and ALKALINE COMPLEXES - PHOSPHATE, NIOBIUM, TITANIUM AND REE
A cluster of at least 7 significant carbonatite-alkaline igneous complexes are known, and are exploited for phosphate and/or niobium, titanium and rare earth elements in the Brasilia Belt of Minas Gerais, extending into the Ribeira Belt of São Paulo State to the south. These complexes cover areas up to as much as 65 km², and are an integral part of the Alto Paranaíba Igneous Province which is developed along the Alto Paranaíba Arch, and also includes hundreds of kimberlite intrusions and kamafugites intrusives, lavas and volcanoclastic units. The carbonatite intrusions in the main igneous province, which span the interval of 120 to 70 Ma, include (ages after Eby and Mariano, 1992): Tapira, P, Ti (81.7 to 78.6 Ma), Araxá, P, Nb, REE (85.6 to 80.3 Ma), Salitre I, II and Sierra Negra, P, Ti (Salitre I - 93.8 to 85.4 Ma; Serra Negra - 79.1 Ma), Catalão I and II, P, Nb (Catalão I - 114.3 to 109 Ma; Catalão II - 89.8 Ma).
Further south, within the Neoproterozoic Ribeira Belt (Fig. 1), ~200 km SW of São Paulo city, the Jacupiranga phosphate-carbonatite was emplaced at130 ±4 Ma.
The much older Angico dos Dias carbonatite-alkaline igneous complex occurs as part of a cluster of Palaeoproterozoic (~2.0 Ga) mafic-utramafic and carbonatite intrusions scattered over a 20 km radius area on the northern margin of the São Francisco Craton, immediately to the west of the town of Campo Alegre de Lourdes. Other intrusives in the same cluster separately host Ni-Cu-Co mineralisation (see the Nickel section above) and the Fe-Ti-V deposits (see the Fe-Ti-V section above).

PHOSPHORITE
Phosphorite beds are found at a number of stratigraphic positions within the Brasilia Belt within both the Late Mesoproterozoic to Neoproterozoic overlapping Paranoá-Canastra-Vazante groups and the Neoproterozoic Bambuí and Ibia groups. The principal mines exploit the Rocinha (or Patos de Minas) and Lagamar deposits in Miinas Gerais.

AMAZONIAN CRATON

For a description of the Amazonia Craton that bounds the Atlantic Shield to the west, see the Carajás IOCG Province record. The craton is bounded to the east by the Araguaia and Paraguaia fold belts of the Tocantins Province.

SÃO FRANCISCO CRATON

Until the Mesozoic, the São Francisco Craton was part of the greater São Francisco-Congo cratonic block, much of which is now in Africa. It forms the eastern margin of the Tocantins Province, although shelf facies equivalents of the latter covered much of the craton during the Meso- and Neoproterozoic. It is framed on all margins, except the Atlantic coast, by Palaeoproterozoic Transamazonian and Neoproterozoic Brasiliano orogenic belts.
Along with the adjacent tectonised Borborema Province to the north, which until the Late Neoarchaean had been part of the craton, it contains the oldest rocks in South America. These are predominantly found within the Gavião Block (Fig. 1) in the north-central core of the craton and comprise Palaeoarchaean >3.64 to 3.26 Ga, commonly migmatised, grey, tonalitic-trondhjemitic-granodioritic (TTG) orthogneisses, which form small nuclei, domes and massifs, surrounded by Mesoarchaean and/or Neoarchaean, mainly TTG orthogneisses, representing successive accretionary events. The presence of inherited grains with ages of up to 3.69 Ga and zircon Hf model ages ranging from 3.82 to 4.33 Ga indicate the existence of still older, underlying Eoarchaean, perhaps even Hadaean crust (Delgado et al., 2003). While the bulk of these older rocks occur within the Gavião Block to the north, late Palaeoarchaean 3.22 to 3.20 Ga continental crust has been documented in the southern São Francisco Craton and in subsequently reworked equivalents immediately to its east (Neves et al., 2021).
These old rocks are accompanied by 3.4 to 3.2 Ga Palaeoarchaean meta-volcano-sedimentary sequences composed of mafic to felsic volcanic-sedimentary and sub-volcanic rocks. These include 3.43 Ga TTG and 3.30 Ga rhyolites occurring as a plutonic-volcanic system west of Jacobina, towards the eastern margin of the Gavião Block. These magmatic rocks are located on the margin of a rift, and were related to its formation. This rift evolved into the passive margin Jacobina-Umburanas Sea which extended to the east. Quartzites and conglomerates containing detrital zircons with a relatively narrow age range of from 3.4 to 3.2 Ga were deposited in this sea (U-Pb; Teles et al., 2014), along with pelites, and iron and manganese oxide formations formed in an oxidising regime. The deepest part of the sea contains 3.2 Ga 'ocean floor' pillow-lava basalts (Teles, 2013) whilst 3.296 Ga ultramafic intrusions occur within the basement Gavião Block (e.g., Barbosa et al., 2021). The un-eroded remnant basin has a >180 km length and hosts the quartzite sequence in which the gold-uranium-pyrite bearing Jacobina quartz-pebble conglomerates are intercalated. The Jacobina stratigraphy (after Zincone, et al., 2017) comprises basal upward fining fluvial cycles, commencing with large pebble to cobble conglomerates and coarse grained quartzites, deposited within a proximal to medial braided stream system in a rapidly aggrading wet alluvial fan environment (Hendrickson, 1984). The sequence transgresses into well-bedded quartzite with locally prominent ripple marks, as well as herring-bone and cross bedding that may represent a shallow marine transgression of tide-dominated deltas and littoral sands (Leo et al., 1964; Minter, 1975; Mascarenhas and Silva, 1994; Mascarenhas et al., 1998; Pearson et al., 2005). These rocks are structurally interleaved with i). the ~2595±21 Ma (U-Pb zircon; Spreafico et al., 2019) Mundo Novo Greenstone Belt; and ii). the Saúde Complex which includes silici-clastics rocks that are lithologically similar to those of the Jacobina Group, but contain abundant 2.20 to 2.06 Ga and 2.68 to 2.50 Ga detrital zircons. These relationships have previously been interpreted to indicate a Palaeoproterozoic age for the Jacobina conglomerates, although detailed work by Spreafico et al. (2019), reinforced by Barbosa et al. (2021), indicate the three sequences represent separate, structurally juxtaposed depositional/magmatic events in the Palaeoarchaean, Neoarchaean and Palaeoproterozoic, controlled by the long-lived Contendas-Mirante-Jacobina lineament. The latter is a north-south, ~600 km long linear tectonic structure that represents a major sinistral and west vergent composite thrust zone (Zincone and Oliveira, 2017).
Further to the south, the Porteirinha Block (Fig. 1) is a 3371 ±6 Ma Palaeoarchaean TTG gneiss complex that forms the southern extension of the Gavião Block. It has been reworked by the adjacent Neoproterozoic Araçuaí Belt, and is now external to the São Francisco Craton, occurring as a north-south, ~240 km long and ~65 km wide, west vergent allochthonous sheet, that has overridden the margin of the craton, and is bordered to the east and west by Palaeo- to Mesoproterozoic and then Neoproterozoic successions. It has been subjected to metamorphic overprinting at 3146 ±24 Ma in the Palaeoarchaean and ~600 Ma in the Ediacaran of the Neoproterozoic (Silva, 2016).

A number of Mesoarchaean blocks have been recognised within the craton, predominantly composed of an association of granite-gneiss complexes and greenstone belts, occurring as domes and remnant keels respectively. These blocks, which were stabilised in the late Mesoarchaean, were the first rigid continental plates and microplates in what was to become the São Francisco Craton. They include much of the Quadrilátero Ferrífero Block and its possible northeastern continuation, the Guanhães Block in the Araçuai Belt in Minas Gerais. They also include the Serrinha Block and are found on the Gavião Block in Bahia.
The Archaean basement of the Quadrilátero Ferrífero Block is exposed as a series of irregularly shaped domal structures, largely composed of TTG gneisses, each of which is defined by lithological differences, with each being considered as an individual 'complex' (Aguilar et al., 2017). These domes vary from <25 to >200 km in diameter. They are largely separated by smaller (<1 to 40 km diameter) aligned domes of 2760 to 2680 Ma granitoids, and linear keels composed of Neoarchaean greenstones and Palaeoproterozoic volcano-sedimentary and sedimentary rocks. The principal domes are the Bonfim, Bação, Belo Horizonte, Santa Barbara, Caeté and Divinópolis complexes. In detail, the Archaean TTG crustal evolution of the Quadrilátero Ferrífero has been divided into at least five main magmatic events (Lana et al., 2013; Farina et al., 2015; Araújo et al., 2020). The oldest was the Santa Bárbara Event, between ~3.22 and 3.20 Ga in the late Palaeoarchaean (Lana et al., 2013) which occurs as an 'older TTG' in a restricted area of the Santa Barbara Complex in the SE of the block, and subsequently deformed equivalents in the adjacent orogenic Mineiro Belt. Although exposures of these older rocks are limited, Sm-Nd model ages from the TTG rocks (Teixeira et al., 1996) and the abundance of 3.6 to 3.0 Ga detrital zircons in surrounding Neoarchaean and Palaeoproterozoic sequences, suggest Palaeoarchaean rocks were once more widely exposed in the area (Lana et al., 2013). The second of these periods of accretion was the Rio das Velhas I Event between ~2.93 and 2.85 Ga which produced juvenile TTG magmatism, now orthogneisses, and the accretion of mafic-ultramafic greenstone terranes to the pre-existing crust. This event accounted for the bulk of the TTG magmatism in the complexes listed above, particularly in the Bação, and large Belo Horizonte, Divinópolis and Bonfim complexes/domes. The remaining Neoarchaean 2.80 to 2.76 Rio das Velhas II Event and coeval deposition of the Rio das Velhas Supergroup, followed by the 2.75 to 2.65 Ga relatively K-rich Mamona Magmatic I Event and final minor magmatic pulses of the Mamona Magmatic II Event between 2.65 and 2.58 Ga (Lana et al., 2013; Farina et al., 2015; Dopico et al., 2017) that will be discussed in more detail below. The information in this paragraph was drawn from Lana et al. (2013); Aguilar et al. (2017); Dutra, Martins and Lana (2019); Baltazar and Lobato (2020); Rossignol, et al. (2020); Araújo et al. (2020); and other sources. For more detail see the Quadrilatero Ferrifero District Gold - Geological Setting record.

The Guanhães Block (Fig. 1) is an uplifted section of the pre-Rhyacian (i.e., pre-2300 Ma) basement to the rift-sag basin into which the meta-sediments of the Espinhaço Supergroup and equivalent sequences were deposited. It is largely composed of 2867 ±10 Ma to 2713.3 ±6.5 Ma - (Silva et al., 2002; Silveira Braga et al., 2019) Mesoarchaean TTG orthogneisses. These gneisses are intruded by large plutons of late Palaeoproterozoic (Statherian) 1750 to 1710 Ma Borrachudos Suite anorogenic alkaline meta-granites which extend for ~250 km NNE from the Quadrilátero Ferrífero. These plutons dominate the internal structure of the tectonic slices between regional shear zones. It has been highly deformed, also representing basement to the Neoproterozoic Araçuaí Orogen sequence (as described later in the Araçuaí Block/Orogen section below). This deformation is the result of strong metamorphic-structural Ediacaran overprinting, accompanied by granitic intrusions of the same age. Deformed tectonic slices/fragments of amphibolite facies iron formation-bearing sequences are discontinuously exposed (Brito Neves et al., 2014; Noce et al., 2007) within the Guanhães Block. These fragments comprise the Guanhães Group which consists of schists, quartzites and paragneisses, interpreted as having a metavolcano-sedimentary origin (Grossi-Sad et al., 1989, 1990; Grossi-Sad 1997) and on the basis of geochronologic studies are correlated with the upper Paleoproterozoic Serra da Serpentina and Serra de São José Groups of the southern Espinhaço Range/Domain. These units were deposited from the end of the Orosirian to the beginning of the Statherian periods in the early opening stages of the Espinhaço basin (Rolim et al., 2016). The upper quartzite of this sequence, which grades upward into the Lower Espinhaço Supergroup in the southern Espinhaço Range, has yielded detrital zircons dated at 1685 Ma (U–Pb LA-ICP-MS; Santos et al., 2013). All units were intruded by anatectic pegmatites bodies of the Eastern Brasilian Pegmatite Province between 630 and 480 Ma (Gomes et al., 2018; Pedrosa Soares et al., 2011; Silveira Braga et al., 2020; Silveira Bragaet et al., 2019).
The Serrinha Block (SB), to the NW of the city of Salvador (Fig. 1), is divided into two high grade gneissic complexes, the Santa Luz and Uauá to the SW and NE respectively (Baldim and Oliveira, 2021). Both are largely composed of migmatitic and granulite facies orthogneisses with a predominantly juvenile TTG composition. The Uauá Complex is made up of granulite facies granites and granodiorites of calc-alkaline composition to TTG, with ages varying between ~3.2 and 2.96 Ga (e.g., Oliveira et al., 2010, 2013, 2019). It is characterised by abundant undeformed mafic dyke swarms dated at 2726 and 2642 Ma, filling faults and cutting penetrative foliations in granulite facies metamorphic rocks (Oliveira et al., 2012; 2013; Barbosa et al., 2020). These dykes are interpreted to represent a major LIP, but also implies a period of early Neoarchaean extension following its initial deformation. In contrast, the Santa Luz Gneissic Complex is composed of calc-alkaline to TTG rocks, predominantly granodioritic in composition with ages varying between ~3.16 and 2.99 Ga (Rios et al., 2008; Oliveira et al., 2010). The orthogneisses of the block have TDM model ages that range from 3.62 to 3.45 Ga (e.g., Bueno and Oliveira, 2002) and 3.11 to 2.92 Ga (e.g., Oliveira, 2001), indicating heterogeneous sources, and a likely Palaeoarchaean continental basement.
The Gavião Block, which is predominantly a Palaeoarchaean core, also incorporates Mesoarchaean rocks. These include the 2954 Ma Santa Izabel Complex in its western part, that encloses older meta-komatiites (Medeiroa et al., 2017; Barbosa et al., 2020). The Gavião Block has an oval shape and is exposed around the margins of large outliers of mainly Mesoproterozoic cover, although its persistance below those younger sequences is indicated by the distribution of a negative Bouguer gravity response (e.g., Gomes et al., 1996) over an area of >300 000 km². Its boundaries are all tectonic, marked by deep regional shear zones.

During the Meso- to Neoarchaean transition, magmatism continued in the Quadrilátero Ferrífero, with the final pulse of TTG magmatism from 2.80 to 2.76 Ga in the early Neoarchaean Rio das Velhas Magmatic II Event. This was followed by the extrusion of suites of meta-komatiites and meta-tholeiites to form 'greenstone belts', with intercalations of silica-iron-manganese formations in the lower section of the stratigraphic pile. Calc-alkaline felsic metavolcanic rocks are also always present, while the upper part of the sequence is made up of metasedimentary rocks subdivided into a lower succession which constitutes an association of schist, graphite, meta-pelite, meta-chert, banded iron formation and calc-silicate rock, and an upper suite of clastic rocks, mainly turbidites. These sequences and intrusives were then intruded by potassic granitoids, and deformed to produce a dome-and-keel architecture by 2.72 Ga (e.g., Farina et al., 2015; Teixeira et al., 2017; Cutts et al., 2019). These rocks were metamorphosed to amphibolite-facies and locally converted into stromatic migmatites during two metamorphic events, as shown by peaks at 2.86 and 2.77 Ga (U-Pb zircon), and were intruded by several generations of Neoarchaean granites over an extended interval of A-type granitoid magmatism that persisted from 2.72 to 2.63 Ga (Moreno et al., 2018; Brando Soares et al., 2020). Three main granitoid suites are recognised during this period in the Quadrilátero Ferrífero: i). 2.78 to 2.72 Ga (U-Pb) metaluminous tonalite, grandiorite and calc-alkaline granite; ii). 2.71 to 2.69 Ga (U-Pb zircon) peraluminous type granitoids; and iii). 2.61 to 2.55 Ga post-orogenic, A-type, grey granite dykes and plutons (Teixeira et al., 2000). The first two of these intrusions are attributed to the 2.75 to 2.68 Ga, Neoarchaean Mamona I Magmatic Event, whilst the third involved relatively minor magmatic events at ~2631 (Moreno et al., 2017) and ~2612 Ma (Romano et al., 2013) and represented the 2.65 to 2.58 Ga Neoarchaean, Mamona II Magmatic Event.

In the Quadrilátero Ferrífero of Minas Gerais, the most economically significant and well studied greenstones are represented by the Rio das Velhas Greenstone Belt. This greenstone belt contains major tectonic and stratigraphic discontinuities that require its division into three fault-bound tectonostratigraphic blocks, the Santa Bárbara (to the east), Nova Lima-Caeté (to the NW) and São Bartolomeu (to the SW), each of which is divided into a separate lithostratigraphy. However, despite some marked differences between these blocks, stratigraphic correlations and a similar depositional evolution is recognisable. The bulk of the sequence comprises the 2.8 to 2.76 Ga (Lana et al., 2013) Rio das Velhas Supergroup, that is, in turn, subdivided into the lower Quebra Osso Group, the ~2.77 Ga Nova Lima and overlying Maquiné groups. Araújo et al. (2020) suggest volcanic architecture and sedimentary depositional models for the studied area that includes:
i). fissure eruption of komatiite lavas of the Quebra Osso Group, in the Santa Bárbara Block only, where it is restricted to a NNE-SSW elongated ~15 x ~0.5 to 1.5 km strip, and is now mostly composed of meta-komatiites;
ii). ultramafic/mafic tholeiitic MORB-like lavas and sills related to multiple volcanic centres in a subaqueous, extensional environment, with chemical-exhalative metasedimentary intercalations, characteristic of the basal Nova Lima Group in the Santa Bárbara and Nova Lima-Caeté blocks;
iii). intermediate to felsic volcanic and volcaniclastic rocks from the Nova Lima Group, restricted to the Nova Lima-Caeté Block, and related to explosive eruptions;
iv). clasto-chemical sedimentation that is well developed in the Nova Lima Group of the Santa Bárbara Block;
v). a thick sequence of clastic sediments deposited at the top of the Nova Lima Group in all three blocks, predominantly composed of greywacke-argillite cycles, deposited by turbidity currents in tectonically active submarine basins. This section is interpreted in Delgado et al., 2003 as a post-eruptive facies of volcaniclastic and epiclastic meta-sedimentary, turbiditic rocks, in a compressive regime during basin inversion;
vi). a sequence of polymitic meta-conglomerates, meta-arenites and meta-pelites of the 2.77 to 2.70 Ga (U-Pb zircon; Moreira et al., 2016) Maquiné Group. This group, which unconformably overlies the Nova Lima Goup, is a post-orogenic terrigenous sedimentary sequence deposited in alluvial/fluvial braided river, coastal and shallow marine environments (Baltazar and Zucchetti, 2007; Moreira et al., 2016).
For more detail see the Quadrilatero Ferrifero District Gold - Geological Setting record.

The other coeval and substantial accretion of Neoarchaen crust took place in the northeastern arm of the craton in Bahia, during the 2.8 to 2.6 Ga Jequié Orogenic Cycle. This orogenic event most influenced the Jequié Block in the SW of that part of the craton, and as the NNW-SSE oriented composite Itabuna-Salvador-Curaçá Belt which covers an open 'S-shaped' area of ~700 x 150 km, wrapping around the Serrinha Block (SB) to the NE and the Jequié Block to the SW (Fig. 1). Together these strongly deformed and metamorphosed tectonic elements separate the Gavião and Serrinha blocks, and are interpreted to have been metamorphosed to granulite facies as these older blocks approached during the Jequié Orogenic Cycle.
The composite Itabuna-Salvador-Curaçá Belt comprises the Itabuna and Salvador-Curaçá belts to the SE and north respectively. Both domains are made up of lithological associations with the same characteristics (after Delgado et al., 2003), namely:
i). a range of paragneisses, grouped into the Almadina Complex to the SE, and in the Tanque Novo-Ipirá Complex to the north. The Tanque Novo Complex paragneisses include Al-rich variants, banded gneisses, calc-silicate rocks, quartzites, iron formations and graphite gneisses (D'el-Rey Silva et al., 2007);
ii). an association of juvenile ~2.58 Ga TTG orthogneisses gathered in the Itabuna Complex in the south, and the Caraíba Complex to the north; the Caraíba Complex orthogneisses are mostly enderbitic and charnocktic orthogneisses, as well as migmatites (D'el-Rey Silva et al., 2007);
iii). mafic and ultramafic rocks, occurring as bodies of pyroxenite, gabbro-norite, gabbro-diorite and meta-basalt in the south, and grouped into the ~2.58 Ga São José do Jacuípe Complex to the north; and
iv). charnockite, granite, tonalite, monzonite/shoshonite intrusions, some of which are related to Palaeoproterozoic evolution.
The Itabuna-Salvador-Curaçá belts were also substantially overprinted and reworked during the Rhyacian (2.30 to 2.05 Ga) to Orosirian (2.05 to 1.80 Ga) periods of the Palaeoproterozoic, as discussed below.
The Jequié Block is mostly composed of juvenile, calc-alkaline, banded orthogneisses, migmatites and relics of supracrustal rocks intruded by an enderbitic-charnockitic suite dated at ~2.7 Ga. These were also strongly reworked during the Palaeoproterozoic (Silva et al., 2002; Barbosa and Sabaté, 2004). As preserved, the block corresponds to the lower crustal segment of an Archaean terrane and is composed mainly of 2.8 to 2.5 Ga orthopyroxene bearing granitic gneisses (Silva et al., 2002; Barbosa and Sabaté, 2004).
The granulite facies metamorphic suite generated in the Itabuna-Salvador-Curaçá belts during the Jequié Orogenic Cycle included quartzite, psammitic and pelitic gneiss, garnet gneiss, calc-silicate rock, graphitic and manganese gneiss, gondite, iron formation and amphibolite bodies. The sequence has been intruded by voluminous felsic TTG orthogneiss and metamafic rock (amphibolite). The latter include banded or granular bodies with the compositions of gabbronorite, norite, gabbro, ferro-gabbro, restricted leuco-gabbro and peridotite, e.g., the Sáo José do Jacuípe Suite, interpreted by Teixeira (1997) as derived from a MORB-type tholeiitic magma, with minor crustal contamination, representing a remnant of obducted oceanic crust. It is suggested this metamorphic suite represents a protolithic sequence of coarse to fine clastic to carbonate sedimentary rocks accompanied by abundant bimodal magmatism, mainly intrusive, with lesser volcanism. Such a sequence would have been deposited in a passive margin to extensional rift setting, laid down on the intervening oceanic crust, between the Gavião, Jequié and Serrinha blocks, lapping onto the margins of those blocks. Deposition of this succession is taken to have occurred after 2.9 Ga (Delgado et al., 2003) with the intrusion of the bimodal magmatism by ~2.58 Ga (Neves et al., 2021). The latter is believed to be the age of the mafic host to copper mineralisation at Caraíba. Inversion and the approach of the older blocks during the Jequié Orogeny led to compression and deformation between the Serrinha and Gavião blocks to the north, and between the Jequié and both the Gavião and West Congo blocks to the west and east respectively, accompanied by subduction, or more likely 'sagduction', and magmatic arc emplacement. Obduction or overthrusting of the oceanic crust that floors the sequence, and subsequent folding and imbrication produced a number of narrow, sinuous greenstone like belts in the Itabuna-Salvador-Curaçá domain, interlaced with ortho- and paragneisses. This 2.7 to 2.6 Ga tectonic activity was responsible for the i). first significant folding of the gold-bearing Serra de Jacobina sequence and metamorphic transformation of the associated manganiferous carbonates to quartz-spessartine Jacobina protore; ii). intrusion of the mafic-ultramafic bodies related to the Cu mineralisation at the Caraíba deposit in the Curaçá Valley; and iii). emplacement of the 2623 Ma, vanadium bearing Jacaré River Gabbro-anorthositic sill (Barbosa et al., 2020).

Another significant Neoarchaean greenstone sequence is that of the Mundo Novo Belt further to the west, within the eastern margin of the Gavião Block (MNGB on See Fig. 1, immediately SE of Jacobina). This greenstone belt has been variously interpreted to have included a range of stratigraphic units and ages, from the Palaeoarchaean Jacobina Group to the to Palaeoproterozoic Saúde complex. However, Spreafico, et al. (2019) consider the Mundo Novo Greenstone Belt to be of a more limited extent than previously envisaged, structurally interleaved with both of these units and older basement. They show it to comprise a suite of meta-volcanic and meta-sedimentary rocks that were deposited at ~2595 ±21 Ma (U-Pb zircon) onto a Palaeoarchaean basement, and was deformed and metamorphosed during a Rhyacian-Orosirian (Palaeoproterozoic) tectono-thermal event. The latter is reflected by granites that bracket the interval between 2106 ±71 Ma and 1975 ±36 Ma (U-Pb zircon). The belt has a preserved strike extent of ~100 km and follows the long-lived, north-south Contendas-Mirante-Jacobina lineament which influenced the rifted margin of the Jacobina-Umburanas Sea in which the 3.55 to 3.22 Ga (Teles et al.., 2015) Jacobina Group was laid down, and subsequently, deposition of the Saúde complex, and finally the tectonic interleaving of all three in the Palaeoproterozoic. The greenstone belt is bounded to the west by the 3.4 Ga TTG basement of the Gavião Block, and to the east by the ~3.33 to 3.30 Ga (U-Pb zircon; Sousa et al., 2018) TTG/tholeiitic bimodal gneiss suite of the Mairi Complex which separates it from the Neoarchaean Itabuna-Salvador-Curaçá belt and Jequié Block to the east (Peucat et al., 2002).
The Mundo Novo greenstone sequence comprises, from the base: i). Lower Sequence - ultramafic metavolcanic rocks, predominantly light green meta-komatiites; ii). Middle sequence - mainly composed of pillowed metabasalts and subordinate tremolitic and other calc-silicate rocks, aluminous schists, BIFs, ferruginous meta-cherts, basaltic meta-andesites, meta-dacites and meta-rhyolites. The meta-dacites and meta-rhyolites have a more restricted distribution and correspond to the top of the middle sequence; and iii). Upper sequence,which is composed of siliciclastic meta-sedimentary rocks, including meta-arenites, quartzites, meta-greywackes, meta-siltstones and phyllites, which cumulatively account for ~50% of the greenstone belt sequence. To the north, these are developed over a width of as much as 12 km, whilst to the south, they are as narrow as <1 km.
Spreafico, et al. (2019) envisage the formation of the Mundo Novo Greenstone Belt to have involved the approach from the east of the Mairi Complex, ahead of the advancing Jequié and Serrinha blocks. The Mairi Complex is interpreted to have been a microcontinental sliver that may have previously been rifted from the margin of the Gavião Block. The Mundo Novo magmatism is thought to have been formed as an arc or back-arc generated by intraoceanic subduction to the east of the Gavião Block, which was subsequently obducted onto the Gavião Block during the Palaeoproterozoic.

The Neoarchaean Rio das Velhas and Jequié orogenic cycles reflect the amalgamation of Mesoarchaean and older blocks (e.g. the Serrinha, Gavião and Quadrilátero Ferrífero blocks) to form the São Francisco and Congo protocontinents (also known as the combined Paramirim Craton) from 2.77 Ga onwards. During this period, the neighbouring Borborema Province was also part of the proto-São Francisco Craton and remained so until it was dismembered during the late Neoproterozoic Braziliano Event.
The tectonic consolidation that resulted from this Neoarchaean approach and compression was succeeded by a period of tectonic relaxation and relative stability during the Early Palaeoproterozoic, and the development of widespread continental rifting, shelf and passive margin sequences. The Early Palaeoproterozoic passive margin successions and volcano-sedimentary belts, which are individually described below, were followed by the Transamazonian Orogeny/Event, which occurred in at least two main phases from ~2.25 to 2.10 and ~2.06 to 2.00 Ga during the Rhyacian and Orosirian periods of the Palaeoproterozoic (Hartmann et al., 2006). The sequences affected by this event are widely distributed, both over the São Francisco Craton and marginal to it, where older rocks have been significantly metamorphosed and reworked to granulitic facies and to migmatites. This was particularly prevalent in the Itabuna-Salvador-Curaçá belts and in the Mineiro Belt on the southern tip of the Quadrilátero Ferrífero Block, but also within the Goiás Massif as discussed later. It is interpreted to reflect renewed advance of the the marginal Serrinha and Jequié Blocks and other marginal domains.
In addition, this Transamazonian reworking has resulted in the development of voluminous Rhyacian to Orosirian granitoids and syenites, which have been divided into: i). an older group, mainly emplaced between 2.15 and 2.08 Ga, and comprises plutons that have largely been converted to orthogneisses and granulite; and ii). a younger suite of less deformed to undeformed plutons, mostly intruded between 2.08 and 2.04 Ga (Peucat et al., 2011; Santos-Pinto et al., 2012; Cruz et al., 2016; Nascimento et al., 2017; Bersan et al., 2020). These have been largely intruded into the Itabuna-Salvador-Curaçá belts, Quadrilátero Ferrífero, Gavião, Serrinha and Jequié blocks. Regional metamorphism, partial melting and granitoid intrusion predominated in most of these domains, with limited addition of juvenile material to the crust (Santos-Pinto et al., 2012; Cruz et al., 2016). Syenite plutons predominate within the Itabuna-Salvador-Curaçá belts (e.g., Peucat et al., 2011; Barbosa and Barbosa, 2017). In contrast, Palaeoproterozoic juvenile accretion in the Serrinha Block occurs as granite-greenstone terranes, composed of thick 2.14 to 2.09 Ga mafic and intermediate metavolcanic sequences (Oliveira et al., 2010) and ~2.13 Ga trondhjemitic plutons (Nascimento et al., 2017).

On the southern extremity of the craton, in the Quadrilátero Ferrífero Block, initiation of Palaeoproterozoic extension was marked by the emplacement of the ~2.55 Ga (Caxito et al., 2020) Lavras mafic dyke swarm, and deposition of the Minas Supergroup. This supergroup is an up to ~6000 m thick sedimentary pile comprising various clastic, carbonate and chemical sedimentary units. It includes lower conglomerates (e.g., the auriferous and uraniferous Moeda Conglomerate) overlain by phyllites and cherts of the Caraça Group, estimated to have a maximum depositional age of ~2545 Ma (recalculated by Rossignol, et al. 2020, after Martinez Dopico et al., 2017). These are conformably overlain by the Itabira Group that is predominantly composed of iron oxides, recrystallised chert, limestone and dolostone with subordinate shale and volcaniclastic layers. The latter group is composed of two units, the lower Cauê Formation that comprises silicic and dolomitic banded iron formation (BIF) grading vertically and laterally into dominantly dolomitic rocks of the mainly overlying Gandarela Formation. Pb-Pb dating of carbonates from a stromatolite of 2420 ±19 Ma and an unconformably overlying 2199 ±24 Ma basalt provides a minimum age for the Caraça Group (Rossignol, et al., 2020). Tectonic stability continued until deposition of the pelitic succession at the top of the overlying Piracicaba Group, which was modified at ~2.22 Ga by the beginning of the Transamazonian tectono-thermal event that continued through the deposition of the 2127.2 ±6.9 to 2098 ±33 Ma, unconformably overlying Sabará Group, the uppermost member of the Minas Supergroup.
According to Neves et al. (2021), between 2.47 and 2.13 Ga, roughly coeval with deposition of the Minas Supergroup in the passive margin/rift that was the Minas Basin, an extended episode of juvenile TTG magmatism took place to the south in the Mineiro Belt (Seixas et al., 2012, 2013; Ávila et al., 2014; Teixeira et al., 2015; Barbosa et al., 2019). This belt is interpreted to represent an accretionary orogen above a south dipping subduction zone consuming the oceanic crust that is the substrate of the distal Minas Basin to the north. Subsequent collision and obduction/imbrication of the Mineiro Belt over the southern Quadrilátero Ferrífero, led to the inversion of the Minas Basin at ~2.12 to 2.13 Ga and reworking of the Archaean/Siderian crust, accompanied by high-grade metamorphism, between 2.14 and 2.05 Ga (Ávila et al., 2014; Teixeira et al., 2015; Moreira et al., 2019). This tectono-thermal event was part of the Transamazonian event and is marked by a granulite facies metamorphic peak at 2.08 Ga and intense Palaeoproterozoic calc-alkaline plutonism. It is interpreted to have produced three suites in the southern Quadrilátero Ferrífero and Mineiro Belt, namely: i). calc-alkaline 2.22 to 2.13 Ga gabbro-diorite; ii). 2.18 to 2.16 Ga TTG; and iii). 2.12 Ga, highly differentiated S-type peraluminous bodies and less evolved high-K metaluminous to peraluminous granitic intrusions (Quéméneur and Noce, 2000).
See the separate Quadrilátero Ferrífero District Gold - Geological Setting and Quadrilátero Ferrífero Iron records for more detail of the geology of this region. The Mineiro Mobile Belt, which forms the southern tip of the Quadrilátero Ferrífero Block and São Francisco Craton, was subsequently strongly overprinted by the Neoproterozoic Ribeira Mobile Belt which collided with, and sandwiched it from the south.

Another Palaeoproterozoic passive margin sequence is found on the northern margin of the craton, represented by the Colomi Group. This group occurs as a limited set of isolated mountain ranges overlying the northern margin of the Gavião Block (see the Colomi Fe deposit on Fig. 1), which in this area, is also known as the Sobradinho Block. As in the Minas Supergroup, the Colomi Group is dominated by thick banded iron formations (Itabirite), commencing with a lower clastic sequence of metaconglomerate, metarenite and metapelite and hosts significant resources of magnetite iron ore and lesser supergene hematite. These grade upwards into a shallow marine sequence, composed of carbonate and iron formations, and ends with a siliciclastic sequence (phyllite and orthoquartzite) deposited in a deltaic environment.

Palaeoproterozoic sequences are also preserved along the eastern margin of the Gavião Block forming a two part belt. The northern of these, the Saúde Complex is structurally interleaved with the older Jacobina Group and Mundo Novo Greenstone belt, as discussed previously, while the southern, 190 km long, north-south trending Contendas-Mirante volcano-sedimentary belt, occurs as a tight synform pinched between the Archaean Jequié and Gavião blocks.
The 2150 to 2075 Ma Saúde Complex to the north, is distributed over a strike length of ~400 km, separated from the Jacobina Group to the west by the west vergent Pindobaçu Fault, and is bounded to the east by the major Filadelfia Thrust Zone, above which the Caraíba Complex of the Itabuna-Salvador-Curaçá Belt has been thrust west over the Gavião Block. Due to the different magnetic character of the two suites, the latter fault is reflected as a major magnetic anomaly/discontinuity. The complex is composed of a <10 to >20 km wide, north-south strip of metasedimentary rocks, mainly meta-greywacke and meta-pelite, with minor muscovite-quartzite and metaconglomerate. These sedimentary rocks unconformably overlie the grey gneiss of the Gavião Block, and have been subjected to increasing metamorphic grades. The biotite and muscovite-bearing meta-greywacke and meta-pelite unit has preserved sedimentary structures, e.g., cross-bedding and ripple marks, whilst the higher metamorphic facies unit is defined by staurolite, cordierite and kyanite, with local centimetre-size quartz +sillimanite +muscovite nodules (Zincone, et al., 2017). Garnet-bearing migmatitic-gneiss and quartzite are found in the southern Saúde Complex, with compositional banding that is commonly upright, and a peak metamorphism calculated at 700 to 750°C and 3.5 to 4.5 kbar (Leite et al., 2007). The Saúde Complex contains abundant 2.20 to 2.06 Ga and 2.68 to 2.50 Ga detrital zircons mainly derived from the eastern Itabuna-Salvador-Curaçá Orogen and reworked Neoarchean rocks within that orogen, mainly the Caraíba magmatic arc (Zincone, et al., 2017).
The Contendas-Mirante Belt (CMB), to the south, is interpreted to represent a fault dislocated Palaeoproterozoic foreland basin developed during the approach of the Jequié and Serrinha blocks from the east. It is composed of a Lower and Upper Group. The Lower Group includes the Travessão Member composed of crenulated meta-claystone, grey phyllites with carbonaceous layers, reworked chert and banded iron formations. This member also encompasses a 20 km ridge of quartzite, characterised by rounded 3338 Ma to 3234 Ma detrital zircons, and contains layers of conglomerate and recrystallised quartz pebbles, with abundant barite. It surround the 3.30 Ga Contendas rhyolite, although contacts between the two have not been observed (Zincone et al., 2016; Marinho et al., 1994). As such this member may in part represent a southern extension of the Palaeoarchaean Jacobina Group. Similarly, the Travessão Member banded iron formation yielded a Pb-Pb isochron of 3256 ±51 Ma, which was interpreted as the age of sediment deposition (by Marinho et al., 1994). The second unit within this Lower Group, the Jurema Leste Member, is composed of meta-basalts and meta-andesites with minor interlayered schists, banded iron formations and meta-ultramafic rocks. It is followed by the Santana Member a biotite-garnet schist, intercalated with amphibolite, meta-basalts, meta-andesites and calc-silicate rocks. Despite the degree of metamorphism, some rocks preserve igneous and sedimentary primary structures, e.g., amygdales, porphyritic texture, graded bedding and ripple marks (Marinho et al., 1978, 1994). The Upper Group comprises the Mirante, Rio Gavião and Areião formations, which may correspond to different metamorphic facies of the same upward coarsening protolithic siliciclastic sequence. The Mirante Formation consists mainly of chlorite, staurolite, quartz and magnetite bearing schist, phyllite and meta-greywacke. This is followed by the lower metamorphic grade facies of the Rio Gavião Formation, mainly composed of grey to grey-green phyllite. These two units were interpreted to represent a flysch-type basin with epiclastic and pelitic-psammitic sediments with associated minor volcanoclastic (Marinho et al., 1994). The uppermost Areião Formation is interpreted to represent the transition from an epicontinental to a marine environment, with associated fluvial-deltaic facies comprising meta-arenites and meta-arkoses with decametre to metre-scale cross bedding and millimetre to centimetre-scale dark magnetite and hematite rich layers (Marinho et al., 1994). All of these units, with the exception of the Travessão Member, contain suite of detrital zircons the youngest of which are Palaeoproterozoic in age. The youngest zircon population of the Lower Group is 2092 ±17 Ma and of the Upper Group is 2084 ±15 Ma. The minimum age of deposition is set by the U-Pb crystallisation age of 2045 ±26 Ma of the undeformed granite that cuts all of these rocks. Low to medium grade 3.40 to 3.35 Ga granite-gneiss massifs of the Gavião Block occur as up to 80 km long domes in the SE of the supracrustal belt and in the neighbouring Jequié Block (Nutman and Cordani, 1993; Martin et al., 1997; Zincone et al., 2016). These are interpreted to have been up-domed during emplacement of the 2045 ±26 Ma granitic rocks (Zincone and Oliveira, 2017).

Other supracrustal belts overlying the eastern Gavião Block include the Ibitira-Brumado, Guajeru, Licínio de Almeida, Riacho de Santana and Urandisequences, occurring as remnant outliers and in-folded keels, exposed progressively to the west from the Contendas-Mirante Belt. These are interpreted to be of Palaeoproterozoic age, based on lithological similarity, stratigraphic position and very limited detrital zircon dating work. The Ibitira-Brumado sequence, for example, comprises amphibolites, banded iron formations, gneisses, metacherts, marbles and schists and is interpreted to be of Lower Palaeoproterozoic age. These remnants are taken to suggest an extensive Palaeoproterozoic coverage of the Gavião Block, several hundred million years after the Neoarchaean greenstone belts and meta-volcanosedimentary rocks. It is composed of siliciclastic and chemical lithologies, with a lesser 2.15 to 1.96 Ga Rhyacian volcanic components. This cover was the result of the invasion of the Caraíba-Juazeiro-Ipirá-Contendas Sea that included deposition of the sequences of the Contendas-Mirante Belt and Saúde Complex. However, the maximum deposition age of ~2010 Ma from some of these exposures further to the west suggests that basin development over the Gavião block continued after closure of the main Contendas-Mirante Belt (Zincone and Oliveira, 2017). As in the Contendas-Mirante Belt succession, thin basal units of quartzites and quartz-pebble conglomerates are recognised which have been correlated with the late Palaeoarchaean Jacobina Group. This would imply the Gavião Block remained stable for over a billion years, and/or the Jacobina Group was protected by a since removed cover sequence.

The Caraíba-Juazeiro-Ipirá-Contendas Sea is also interpreted to have spread eastward over the Itabuna-Salvador-Curaçá Belt/Orogen during the hiatus in the early Palaeoproterozoic. This deposition is represented by structural remnants that are now quartzites, graphite gneisses, olivine-marbles, serpentine-marbles and other calc-silicate rocks that host phosphate, apatite-marbles and limestone. These rocks are characterised by negative Ce and positive Eu anomalies, which reinforces the interpretation of their deposition in a relatively shallow, oxygenated marine environment (Ribiero, 2017). The sequence also includes a few Rhyacian (2151-1960 Ma) volcanic components, and is interpreted to have been deposited ~400 to 500 m.y. after the emplacement of the preceding Meso- and Neoarchaean rocks of the belt (Barbosa et al., 2020).

Further to the NE, the Palaeoproterozoic is represented by the 150 x 50 km, NNW-SSE aligned Rio Itapicuru Greenstone Belt, and its more restricted neighbour to the east, the Rio Capim Greenstone Belt, both of which are infolded into the underlying Mesoarchaean Serrinha Block. The Rio Itapicuru Greenstone Belt partially separates the Santa Luz and Uauá complexes that together constitute the Serrinha Block (SB). The succession within these greenstone belts is known as the Monteiro Sequence. It comprises a basal unit composed of ~5000 m of massive, porphyritic, variolitic and amygdaloid basalt and pillowed basalt flows, and lenses and layers of flow breccias, with fine intercalations of chert, banded iron formations and graphitic shales. These basalts are P-MORB tholeiitic metabasalts (Silva, 1987). They are overlain by a sequence of dacitic and andesitic lavas and volcaniclastic rocks, also containing intercalations of chert and banded iron formations. These volcanic rocks were emplaced during the Rhyacian Period, between 2148 and 2081 Ma (Barbosa et al., 2021). The upper unit is essentially an epiclastic suite, composed of conglomerate, sandstone and pelite derived from the older volcanic members (Mascarenhas 1979; Kishida 1979; Silva 1983; Silva et al., 2002; Oliveira et al., 2007). This epiclastic sequence was also deposited between 2145 and 2080 Ma (U-Pb zircon of all members; Silva et al., 2002; Oliveira, 2010; and Ruggiero and Oliveira, 2010). However, Zincone and Oliveira (2017) state that the youngest zircon population in sedimentary rocks spans the interval between 2137 and 2125 Ma, and these rocks were intruded by potassic plutons between 2111 and 2106 Ma. Silva and Cunha (1999) interpreted the sequence to represent deposition in an extensional regime within a rifted intra- or back-arc regime developed within the Serrinha Block basement (Barbosa and Barbosa, 2017). The sequence has been metamorphosed to greenschist to amphibolite facies in a compressional-to-transpressional setting (Silva et al., 2001). ⁴⁰Ar/³⁹Ar dating of sericite in hydrothermal haloes around gold-bearing quartz veins of the Fazenda Brasileiro deposit hosted by the sequence produced minimum cooling ages of ~2050 ±4 and 2054 ± Ma (Vasconcelos and Becker 1992; Mello, 2000), roughly coeval with crystallisation of the surrounding syntectonic granitoids (Alves da Silva et al., 1993).

Further still to the east, east of the intervening Cretaceous Recôncavo-Tucano Basin, a NNE-SSW elongated strip of the craton is exposed in the form of the Salvador-Esplanada-Boquim Belt. It consists of migmatitic orthogneisses of alkaline to subalkaline affinity, and tonalitic, charno-enderbitic and charnockitic orthogneisses with calc-alkaline affinity. The succession also includes 2.9 Ga tonalitic to granodioritic orthogneisses (Silva et al., 2002), as well as amphibolite facies metamorphosed tholeiitic gabbros and alkaline granites with tendency (Delgado et al., 2002). These rocks have been grouped into four suites: i). predominantly orthogneisses with ultramafic and mafic enclaves, all metamorphosed to granulite facies; ii). granulites facies paragneisses; ii). monzo-syenogranitic intrusions and veins; and iv). mafic dykes. Dating includes sample that yielded SMRIMP magmatic zircon ages, as follows: orthogneiss - 2169 ±48 Ma (Silva et> al., 2002); granodiorite - 2954 ±25 Ma; (Silva et al., 2002); Enderbite - 2561 ±7 Ma (Silva et al., 1997); Granite - 2064 ±36 Ma (Souza et al., 2014), while the metamorphic age of the Enderbite - 2089 ±11 Ma (Silva et al., 1997).
Barbosa et al. (2005) recognised at least three stages of continuous deformation of the granulite facies rocks. The first stage, D1 involved recumbent folding with sub-horizontal axes, which were isoclinally refolded during D2 with subvertical axial planes and subhorizontal axes. The third phase, D3, includes transcurrent dextral shearing, subparallel to the axial surfaces of the isoclinal folds, and coeval with the second deformational phase, to produce mineral stretching lineations parallel to their axes. U-Pb monazite ages (in situ LA-ICPMS) indicate that the third deformational phase occurred at 2064 ±9 Ma (Souza 2013). These phases are cut by numerous post-D3 faults and fractures. The most significant strike at 60 to 90%° and control the occurrence of numerous 2015 Ma (Oliveira, 2014) alkaline basaltic dykes. Monzo- syenogranitic tabular bodies and veins were emplaced in ~120 to 160° set of faulst and fractures and have been dated at 2064 ±36 Ma (U-Pb zircon, SHRIMP, Souza et al., 2014).

Geophysical data, including gravity, show that the crust below the Itabuna-Salvador-Curaçá Belt is thinner and the mantle shallower than below the adjacent blocks, with brittle-ductile and brittle structures well developed in areas of granulite facies metamorphism. It also shows that this thincrust has persisted from before the crustal attenuation related to the Mesozoic separation of Brazil and Africa, and was probably linked to Palaeoproterozoic tectonics (Barbosa et al., 2021). As such it may infer delamination and detachment of SCLM (or a sagduction lobe) from below the Itabuna-Salvador-Curaçá Belt/Domain, leading to upwelling of the asthenosphere, reinforcement of high temperature metamorphism and anatexis, followed by rapid uplift of the less dense crust to expose the high grade metamorphic/migmatised core of the domain. The distribution of Palaeoproterozoic high grade metamorphism, migmatites and related voluminous Rhyacian to Orosirian granitoids and syenites onto the margins of the Gavião, Serrinha, Jequié and Salvador-Esplanada-Boquim Belt blocks suggest this delamination and detachment may have been more extensive. Brittle fracturing and introduction of mafic dyke swarms is consistent with rapid uplift, cooling and expansion.

The Rhyacian-Orosirian Transamazonian orogenic cycle was followed by a long period of extensional tectonics (taphrogenesis) that began between 2.05 and 2.08 Ga in the Orosirian, although there was a gap of 100 to 200 m.y. in the geological record before deposition was renewed, accompanied by volcanic and plutonic rocks aged between 1.78 and 1.70 Ga (e.g., Danderfer et al., 2009; Danderfer Filho et al., 2015; Chemale et al., 2012; Lobato et al., 2015; Costa et al., 2018). Sedimentation was initially accompanied by the emplacement of large banded mafic-ultramafic complexes of gabbro-anorthositic, syenitic and alkaline suites, and carbonatites, in both the central Tocantins Province and on the São Francisco Craton. Extension continued into the Statherian, with rifting being accompanied by intraplate anorogenic magmatism that was dominantly crustal derived A-type granitoid suites, bimodal volcanism and sedimentary rift sequences. Rifting expanded into the Calymmian at the beginning of the Mesoproterozoic creating extensive rift-sag basins, although extension to the point of oceanic floor formation is not recorded until ~1.3 Ga in the Ectasian Period, which lasted until the Stenian at the end of the Mesoproterozoic.
The principal control on this deposition was the NNW-SSE elongated Paramirim Aulacogen, a composite rift-sag zone that transects the Gavião Block of the craton and extends to the south into what became the Neoproterozoic Araçuai Belt. A second, smaller, semi-parallel rift, the Pirapora Aulacogen similarly cuts across the craton, some 300 km to the south, but is largely masked by younger cover (e.g., Bittencourt et al., 2019). The Paramirim Aulacogen was divided into two subsiding basins, the narrower ~500 x 40 km Northern Espinhaço Domain (NED) to the west, and the broader 400 x 200 to 300 km Chapada Diamantina Domain (CDD) to the east (Guimarães et al., 2012), separated by the Paramirim Block (PB; Cruz et al., 2012). The latter represents one of the thickest parts of the continental crust of Bahia. It is largely occupied by Archaean basement rocks of the Gavião Block which were uplifted during the Neoproterozoic Brasiliano Orogenic Event, but was also a basement high through most of the late Palaeoproterozoic and Mesoproterozoic.
The Northern Espinhaço Domain has been more strongly deformed than the more flat-lying Chapada Diamantina Domain, and in contrast to the latter, continues to the south along the western margin of the Araçuai Belt towards the Quadrilátero Ferrífero and to the east, suggesting equivalent facies continue beneath the Neoproterozoic cover.
The principal succession deposited through this period of late Palaeoproterozoic to lowermost Neoproterozoic extension was the Espinhaço Supergroup. Successive pulses of rifting within the Paramirim Aulacogen punctuated the Espinhaço Supergroup into three successions, each separated by a hiatus. These were the Late Palaeoproterozoic Stratherian Lower Espinhaço; the Middle Espinhaço, which was further split into an Mesoproterozoic upper-Calymmian and mid-Ectasian section; and the Stenian to lowermost Tonian Upper Espinhaço which encroached into the Neoproterozoic. The cumulative thickness of the Espinhaço Supergroup in the Northern Espinhaço and Chapada Diamantina domains is 9300 and 5000 m respectively (Guimarães et al., 2012).
Deposition of the Lower Espinhaço commenced in the Northern Espinhaço Domain, with a sequence that began with the 1.76 to 1.66 Ga (Dandefer et al., 2015) Serra dos Algodões Formation, composed of metamorphosed psammites, conglomerates and feldspathic arenites; overlain by the Oliveira dos Brejinhos Group, dated between 1.73 to 1.66 Ga, and made up of the Pajeú Formation metamorphosed carbonate, pebble conglomerate and pelite, and the São Simão Formation metamorphosed rhyolites and felsic pyroclastics (Dandefer et al., 2009; Guimararães et al., 2019). The latter formation has been chronologically correlated with the volcanic rocks of the Rio dos Remédios Group of the Chapada Diamantina Domain, which also includes the associated 1.77 Ga Serra da Gameleira Formation metamorphosed quartz-arenite and conglomerate. Volcanism within the Rio dos Remédios Group spans an interval of 1.777 to 1.579 Ga (Guimararães et al., 2014) and comprises rhyolitic and trachytic volcaniclastics, tuffs and lavas, distributed over an area of ~30 000 km² (Barbosa et al., 2021). This volcanism is more abundant in the western part of the Chapada Diamantina where it accompanied rifting, and has been modified by deformation, metamorphism and hydrothermal alteration. No sedimentary rocks were deposited over the basement orthogneiss of the Paramirim Block, although it was covered by volcanic rocks of the Rio dos Remédios Group (Guadagnin, 2014). Intrusive meta-granitoids associated with this period of anorogenic magmatism include the alkaline Lagoa Real Intrusive Suite (Arcanjo et al., 2005), dated at ~1750 Ma (Turpin et al., 1988; Cordani et al., 1992; Lobato et al., 2015), and are principally found within basement rocks of the Gavião Block. These intrusives were deformed to gneisses in shear zones during the Ediacaran Period (Cruz and Alkmim, 2006).
Within the Northern Espinhaço Domain, the Palaeoproterozoic volcano-sedimentary rocks of the Lower Espinhaço were superposed by thick packages of Mesoproterozoic sedimentary rocks deposited in a post-rift 'geosyncline'. The sequence commenced with the 1580 Ma São Marcos Formation metamorphosed quartz-feldspar arenites, pelites and arenites (Dandefer et al., 2009); and the 1514 Ma Sítio Novo Formation metamorphosed conglomeratic quartz-arenite, pelites and arkose (Guimarães et al., 2019). These formations have been regarded as representing the top of the Espinhaço Supergroup in the Northern Espinhaço Domain, and are overlain by rift facies Tonian age Neoproterozoic clastics.
To the east, in the Chapada Diamantina Domain, the Palaeoproterozoic sequence and basement is overlain after 1580 Ma by metamorphosed feldspathic- and quartz-arenites of Paraguaçu Group, also within a post-rift 'geosyncline'. This group is composed of a lower aeolian sequence passing up into marine facies and is composed of metamorphosed fine-grained sandstones, siltstones and argillites. The sequence is cut by 1514 ±22 Ma mafic intrusions. Following a hiatus of ~214 m.y., geosynclinal subsidence re-commenced after ~1300 Ma and continued until ~1140 Ma, resulting in the deposition of the unconformably overlying 180 to 620 m thick Tombador Formation metamorphosed conglomerate, feldspathic- and quartz-arenites, with lenses of 1416 ±8 Ma mafic volcanic rocks (Bittencourt et al., 2019). The succeeding, or laterally equivalent, 460 m thick Caboclo Formation is composed of metamorphosed and silicified quartz-arenites, argilites, siltites and calcarenites that have been dated at ~1436 Ma (Guadagnin, 2014, 2015). Detrital micro-diamonds are found in this domain, occurring in conglomeratic layers and in intrusive rocks (Battilani, 2007), interpreted to have been sourced from the erosion of kimberlite intruding the metasedimentary rocks during deposition and burial of the sequence. These two units are interpreted to be of Upper Calymmian to basal Stennian age in the mid Mesoproterozoic, and make up the lower section of the Chapada Diamantina Group. As with the underlying segments of the supergroup, they represent a progression from aeolian to shallow marine facies. The upper Chapada Diamantina Group is represented by the Morro do Chapéu Formation which was deposited after a break within the Chapada Diamantina Domain. This formation occupies a rift and is widespread over the Chapada Diamantina Domain. It is composed of metamorphosed conglomerates, feldspathic-arenites, siltites and argilites, regarded by some authors as being of late Mesoproterozoic Stenian age (e.g., Bittencourt et al., 2019). However, Barbosa et al. (2021) regard the host rift as ~974 Ma in the Tonian, and as such may represent the basal São Francisco Supergroup, similar to the rifted Santo Onofre and Macaúbas groups in the Northern Espinhaço Domain described below.
To the south, in the Southern Espinhaço Domain (SED), along the western margin of the Araçuai Belt in Minas Gerais, the Palaeo- to Mesoproterozoic Espinhaço Supergroup, is represented by an up to 6000 m thick succession of quartz-rich sandstone, pelite, conglomerate, volcanic rocks and minor carbonate. This succession is only weakly metamorphosed, with sedimentary structures and textures generally well-preserved.
The basement to this sequence is mainly composed of tectonically reworked equivalents of rocks within the São Francisco Craton, predominantly Mesoarchaean to early Neoarchaean gneiss of the Guanhães Block (Fig. 1) that are locally covered by felsic volcanic rocks, and intruded over large areas by anorogenic alkaline granitoid plutons, predominantly leucogranites, of the Borrachudos Suite. The latter are part of a long-lived silicic igneous province developed in the interval between ~1750 and 1710 Ma (Grossi-Sad et al., 1990; Dussin 2000; Magalhães et al., 2018). The felsic volcanic rocks have been dated at 1770, 1719 and 1711 Ma (Brito Neves et al., 1979; Machado et al., 1989) and belong to the lower Espinhaço Supergroup. This magmatism is interpreted to have been anorogenic, related to the onset of rifting.
The basement and the Espinhaço Supergroup are separated by a relatively thin succession that varies from shallow marine to the west to sag phase sedimentary rocks in the east. This intervening succession is overlain by an erosive unconformity.
To the west, toward the São Francisco Craton, this intervening sequence is known as the Costa Sena Group, and comprises shallow marine sericitic quartz schists, quartzites and phyllites with lesser iron formations (e.g., Rolim et al., 2016), which, based on detrital zircons, has a minimum age of 2048 ±16 Ma (Machado et al., 1989). This is unconformably overlain by the basal unit of the Espinhaço Supergroup in that area, the 200 m thick Banderinha Formation. The latter comprises a package of pink to reddish quartz-rich sandstones, containing layers and lenses of coarse conglomerate with a maximum depositional age of 1.737 ±11 Ma, based on detrital zircons (Santos et al., 2013).
Where exposed on the southeastern margin of the Southern Espinhaço Domain, the interpreted equivalent of the Costa Sena Group comprises the 50 to 800 m thick Serra da Serpentina Group which has a maximum Orosirian depositional age, containing youngest 1990 16 Ma detrital zircons. It is composed of fine clastic meta-sediments at the base, and chemical sediments at the top, comprising the Meloso and Serra do Sapo formations respectively. The latter includes economically significant banded iron formations (BIFs) that average 80 m in thickness - see the Minas Rio Project record for details of this sequence.
The basal unit of the Espinhaço Supergroup in the same area, the Serra de São Jośe Group, overlies the banded iron formations of the Serra do Sapo Formation above an erosional unconformity, and also contains banded iron formation. Deposition of these two iron formation bearing suites spans the interval from the late Orosirian to the early Statherian periods, but marks a transition from an epicontinental-epeiric, slowly down-warping sag basin with scant tectonic activity represented by the upper Serra da Serpentina Group, to a tectonically active continental rift-basin during deposition of the Serra de São Jośe Group. The Serra de São Jośe Group has a total preserved thickness of 30 to 650 m, and stretches along the north-south axis of the rift and comprise a complete cycle of transgressive sedimentary deposits, subdivided, from base to top, into the Lapão, Itapanhoacanga and Jacém formations, with the Canjica BIF at the top. The Itapanhoacanga Formation has a maximum depositional age of 1666 ±32 Ma (Statherian), which coincides with the maximum depositional age (i.e., 1683 ±1 Ma) of the overlying São João da Chapada Formation (Rolim et al., 2015). These two formations are interpreted to be equivalents of the Banderinha Formation to the west.
To the east of the Southern Espinhaço Domain, within the basement Guanhães Block, allochthonous slices of a Late Palaeoproterozoic unit known as the Guanhães Group (e.g., Barrote et al., 2017) are interleaved with the Mesoarchaean to early Neoarchaean gneisses. The Guanhães Group comprises, a lower quartzitic unit, overlain by banded iron formation and then further quartzite with garnet-rich amphibolite layers, and have been correlated with the Serra da Serpentina and/or Serra de São Jośe groups.
Within the Espinhaço Supergroup succession, the upper quartzite of the Serra de São Jośe Group (or equivalent Banderinha Formation) grades up into the succeeding São João da Chapada Formation, which is made up of alluvial sandstones with lenses of quartzite breccias at the base, layers of K-rich volcanic rocks (known as hematite-phyllite) and a succession of coarse-grained sandstones with pelitic intercalations. The volcanic rocks are dated at ~1715 ±2 and 1710 ±12 Ma (Machado et al., 1989; Dussin and Dussin 1995; Chemale et al., 2012). This unit is overlain by the Mato Verde Group in the northern part of the southern Espinhaço range, where it also laps onto basement and is separated from the overlying aeolian deposits of the middle Espinhaço sequence by an erosional surface. It is composed of alluvial sandstones and conglomerate grading laterally into lacustine and shallow marine sandstones and pelites of the Panelas Formation, followed by sub-alkaline rhyolitic to dacitic volcaniclastic of the Riacho Seco Formation, dated at 1524 ±6 Ma. The overlying Sopa-Brumadinho Formation was apparently deposited after an ~500 m.y. hiatus with detrital zircons, suggesting an oldest age of ~1192 Ma. The sequence has a maximum thickness of 220 m and is composed of three upward-coarsening cycles, each generally 20 to 50 m thick, which range from pelites, through fine-grained, poorly sorted sandstones (locally ferruginous), to very coarse-grained sandstones and conglomerates or breccias (Martins-Neto 2000). The Galho do Miguel Formation represents a marine transgression onlapping the Sopa-Brumadinho sequence. It is composed of medium to coarse grained, texturally mature, quartzites that are white, and occasionally pinkish. This formation is disconformably overlain by the basal member of the Conselheiro Mata Group, the Santa Rita Formation that is composed of an up to 225 m thick, fine grained grey to locally pink, coarsening upward sequence of siltstone and variable micaceous and friable sandstone, with ripple marks in its upper and lower sections. This unit is gradationally overlain by the Córrego dos Borges Formation, which is up to 140 m thick and composed of medium- to fine- and locally coarse-grained, dark to light grey quartzite, with common centimetric to millimetric foliated metapelitic intercalations. It has a gradational boundary with the overlying Córrego Bandeira Formation, which is characterised by a very friable and weathered, white to grey, medium- to fine-grained quartzite with planar bedding and micaceous intercalations. It thins to the west, from a maximum 85 m thickness in the east. The uppermost unit of the group is the Córrego Pereira Formation, which comprises fine-grained, usually friable, pure quartzite with an incipient micaceous foliation. The upper surface of the formation, group and supergroup varies from a paraconformity, to a locally angular unconformity with the overlying Macaúbas Group (after Filizzola et al., 2019).
This sequence is interpreted to represent an evolution within the Araçuaí Belt that started with the spreading episodes of Late Palaeoproterozoic Statherian rifting, represented by two pulses of felsic volcanism dated at around 1770 and 1711 Ma, the emplacement of the Borrachudos anorogenic plutons around 1730 Ma, and the onset of the Espinhaço intracontinental rifting with the deposition of the Bandeirinha and São João da Chapada formations (Dussin et al., 1994, Chemale et al., 1998, 2012; Fernandes et al., 1994; Silva et al., 2002; Pedrosa-Soares and Alkmim 2011; Santos et al., 2015). Two further rifting and magmatic events occurred, namely the Calymmian 1524 Ma acid magmatism of the Richo Seco Formation (Costa et al., 2014) and Early Stenian at 1180 Ma, during deposition of the Sopa-Brumadinho Formation (Chemale et al., 2012; Santos et al., 2015). The latter, which was superimposed on pre-existent structures of the same nature, was followed by the generation of a large sag basin, in which the aeolian and shallow marine upper units of the Conselheiro Mata Group were deposited (Martins-Neto 2000; Santos et al., 2015).
All of these units were intruded by anatectic pegmatites bodies of the Eastern Brasilian Pegmatite Province, intruded between 630 and 480 Ma (Gomes et al., 2018; Pedrosa Soares et al., 2011; Silveira Braga et al., 2020; Silveira Braga et al., 2019).
The Espinhaço Supergroup was deposited in a basin of the Araçuai Belt marginal to the the São Francisco Craton and was overthrust and imbricated onto the margins of the craton during the late Neoproterozoic Braziliano Event.

The transition to the Neoproterozoic over the São Francisco Craton was marked by a progression from a gently warping geosynclinal regime in both the Chapada Diamantina and Northern Espinhaço domains to rifting, and the the basal units of the São Francisco Supergroup. In the Chapada Diamantina Domain, this sequence is represented by the Morro do Chapéu Formation described above, which was deposited in a ~974 Ma, Tonian, rift. In the Northern Espinhaço Domain, the supergroup is represented by the Santo Onofre and Macaúbas groups, which were deposited in a renewed ~894 Ma rifting event. There has been an absence of robust age constraints on the Cryogenian glaciogenic successions within the region. However, dating of 182 detrital zircon grains by Pacheco et al. (2023) from the Lower Chapada Acauã Formation of the Macaúbas Group, yielded a youngest concordant zircon grain aged 753 ±12 Ma (U–Pb LA-MC-ICP-MS). The Santo Onofre Group is composed of metamorphosed feldspathic-sandstones, lithic-arkoses and quartz-sandstones that are either stratified or massive and grade laterally to pelites, and include beds of oligomictic matrix-supported conglomerates (Guimarães et al., 2008). The Macaúbas Group is predominantly made up of quartzites that are generally micaceous and eventually ferruginous, and pass up into meta-diamictites at the top, and is regarded as an equivalent of the Santo Onofre Group. This rift sequence merged into the sag phase Irecê Basin centred on the Chapada Diamantina Domain, between 874 and 761 Ma in the Tonian and Cryogenian. The floor of the basin is occupied by the persistent, ~100 m thick, 874 Ma, Bebedouro Formation which is composed of massive and stratified diamictites containing angular and rounded clasts of granitoid, schist, phyllite, mafic rocks and quartzites (Babinski, 2011). The glacial periods represented by the Bebedouro Formation produced at least two marine transgressive-regressive cycles, resulting in a rise in the level of the Brasiliano Sea during the transgression to practically cover the entire São Francisco Craton. This affectively led to the formation of a second basin, the São Francisco Basin lapping over older basement and occupying much of the craton SW of the Paramirim Aulacogen, virtually merging with the Irecê Basin over the Chapada Diamantina Domain to its NE. Deposition in these two basins is represented by the Bambuí and Una groups respectively, each comprising a thick succession of carbonate and siliciclastic units, generated by the two or more transgressive-regressive cycles in a shallow epicontinental sea (Sanches et al., 2007).
The Neoproterozoic sequence deposited within these basins as the São Francisco Supergroup is as follows in the Bambuí (and Una) groups, from the base:
• Jequitai Formation (Bebedouro Fm. in the Una Group) - conglomerate, metagreywacke, diamictite, pelite and quartzite of glacial-marine origin, exhibiting striated pavements and dropstones as well as faceted and striated clasts. Diamictites at the top of the Macaúbas Group are part of the same sequence. Equivalents persist outwards from the craton and include the Panelinha Formation on the passive margin to the east and into the Araçuai Belt, also to the east, and into the Brasilia Belt to the west. The Jequitai/Bebedouro and equivalent formations are followed by an unconformity.
• Sete Lagoas Formation - red argillaceous dolostone at the base, overlain by laminated limestones and shale, and an upper unit of clear grey dolarenite stromatolites and teepee structures at the top. These three divisions are known as units C, B and B1 in the Una Group.
• A thinner diamictite, followed by an unconformity, marking the beginning of the second cycle, mainly recognised on the Sergipano Belt margin to the NE where it is known as the Palestina Formation.
• Serra de Santa Helena Formation - grey marl, pelite and siltstone with intercalated black limestone. Unit a in the Una Group.
• Lagoa do Jacaré Formation - black organic-rich calcarenite and calcilutite with oolitic and pisolitic limestones and interbedded pelite and marl. Unit A1 in the Una Group.
• Serra da Saudade Formation - siltstone, pelite and intercalated limestone.
• Três Marias Formation - arkoses and siltstone.
The Sete Lagoas, Serra de Santa Helena and Lagoa do Jacaré formations are collectively known as the Salitre Formation in the Irecê Basin. The sequence is understood to have been deposited during the Cryogenian, between 750 and 600 Ma. Seismic surveys from the central São Francisco Basin indicate the carbonate platform is up to 1000 m thick (Teixeira et al., 1993). In contrast, it reaches only 600 m in thickness in the Sete Lagoas area (Pedrosa Soares et al., 1994) and 600 m in the Irecêe; Basin (Misi 1979). The underlying Meso- and Neoproterozoic metasediments package within the Irecêe; Basin is indicated by seismic data to be 6 km thick (Silva and Sampaio, 2017).

During the Neoproterozoic, the relatively thin Tonian rift and Cryogenian shelf sequences over the São Francisco Craton were largely surrounded by thick sedimentary packages, deposited in marginal marine basins that were subsequently deformed and metamorphosed during the Ediacaran. These marginal sequences included the Araçuai Belt to the SE, the Brasilia Belt to the west, and the Rio Preto, Riacho do Pontal and Sergipano belts distributed around the northern margin of the craton. The deformation of these marginal sequences was the result of the gradual convergence of the surrounding cratons which led to their overthrusting and imbrication onto the margins of the craton. The consequent crustal thickening, in turn, led to the generation of anatectic granites and also the uplift of mountains on the craton margins which contributed clastic detritus to the basins developed on the craton, e.g., the Três Marias Formation that caps the Bambuí Group in the São Francisco Basin (Barbosa et al., 2021). This widespread onset of the Brasiliano Orogeny is reflected in orthogneisses and migmatites of the Gavião Block overprinted by post-Palaeoproterozoic foliations in the south and west of the craton, especially in shear zones that form the boundaries with the enclosing Northern Espinhaço, Chapada Diamantina and Paramirim blocks, with associated biotite being dated at ~656 Ma (K-Ar), in the Ediacaran. Late biotite from Paleoproterozoic granitoids within the Gavião Block have similarly returned K-Ar ages of between 551 and 483 Ma (Barbosa et al., 2012), whilst amphiboles found in amphibolites that occur as enclaves in orthogneisses have been dated between 685 and 545 Ma (Barbosa et al., 2021). This convergence also led to the further elevation and local overthrusting of the Paramirim Block onto the neighbouring sedimentary sequences and the reactivation of the bounding shears from 507 to 483 Ma. It also resulted in the termination of the bulk of Neoproterozoic deposition on the São Francisco Craton.

São Francisco Craton References
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Baldim, M.R. and Oliveira, E.P., 2021 - Northeast São Francisco Craton and West-Congo Craton linked before the Rhyacian (2.10-2.04 Ga) orogeny: Evidences from provenance and U-Pb ages of supracrustal rocks from the Rio Capim greenstone belt, Serrinha Block; Precambrian Research, v.352, 21p. doi.org/10.1016/j.precamres.2020.105985.
Baltazar, O.F. and Lobato, L.M., 2020 - Structural Evolution of the Rio das Velhas Greenstone Belt, Quadrilátero Ferrífero, Brazil: Influence of Proterozoic Orogenies on ItsWestern Archean Gold Deposits; Minerals, v.10, 38p. doi:10.3390/min10110983.
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Barbosa, J.S.F., et al., 2021 - Explanatory Note of the Tectonic-Geochronological Map of the State of Bahia: metallogenetic implications, Bahia Mineral Research Company - CBPM. VIII. Geological Survey of Brazil - CPRM. Special publications series, v.24, 52p.
Barrote, V.R., Rosiere, C.A., Rolim, V.K., Santos, J.O.S. and McNaughton, N.J., 2017 - The Proterozoic Guanhães banded iron formations, Southeastern border of the São Francisco Craton, Brazil: evidence of detrital contamination; Revista do Instituto de Geociencias - USP, São Paulo, v.17, pp. 30-324.
Bitencourt, C.N., Cruz, S.C.P., Cruz, V.A., Pedrosa-Soares, A.C., Paquette, J.L., Alkmim, A.R. and Barbosa, J.S.F., 2019 - Rifting events in the southern sector of the Paramirim Aulacogen, NE Brazil: New geochronological data and correlations for the São Francisco - Congo paleocontinent; Precambrian Research, v.326. pp. 417-446.
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Cruz, S.C.P. and Alkmim, F.F., 2006 - The Tectonic interaction between the Paramirim Aulacogen and the Araçuaí Belt, São Francisco craton region, Eastern Brazil; Anais da Academia Brasileira de Ciências, v.78(1), pp. 151-173.
Cuney, M., Sabate, P., Vidal, P., Marinho, M.M. and Conceicao, H., 1990 - The 2 Ga peraluminous magmatism of the Jacobina- Contendas Mirante Belt (Bahia) Brazil): Major and trace-element geochemistry and metallogenic potential; Journal of Volcanology and Geothermal Research, v.44, pp. 123-141.
Danderfer, A., de Waele, B., Pedreira, A.J. and Nalini, H.A., 2009 - New geochronological constraints on the geological evolution of Espinhaço basin within the São Francisco Craton-Brazil; Precambrian Research, v.170, pp. 116-128.
D'el-Rey Silva, L.J.H., Dantas, E.L., Teixeira, J.B.G., Laux, J.H. and Silva, M.G., 2007 - U-Pb and Sm-Nd geochronology of amphibolites from the Curaçá Belt, São Francisco Craton, Brazil: Tectonic implications; Gondwana Research, v.12, pp. 454-467.
Delgado, I.M., Dalton de Souza, J., Silva, L.C., Silveira Filho, N.C., Santos, R.A. Pedreira, A.J., Guimarães, J.T., Angelim, L.A.A., Vasconcelos, A. M., Gomes, I.P., Lacerda Filho, J.V., Valente, C.R., Perrotta, M. M. and Heineck, C.A., 2003 - Geotectonics of the Atlantic Shield; in Bizzi, L.A., Schobbenhaus, C., Vidotti, R.M. and Gonçalves J.H., (eds.), Geologia, Tectônica e Recursos Minerais do Brasil, CPRM, Serviço Geológico do Brasil Brasília, pp. 227-334.
Farina, F., C. Albert, C., Martínez Dopico, C., Aguilar Gil, C., Moreira, H., Hippertt, J.P., Cutts, K., Alkmim, F.F. and Lana, C., 2015 - The Archean-Paleoproterozoic evolution of the Quadrilátero Ferrífero (Brasil): Current models and open questions; Journal of South American Earth Sciences, v.68, pp. 4-21. doi.org/10.1016/j.jsames.2015.10.015.
Filizzola, B.R., Galvão, F.P. and Roncato, J., 2019 - Stratigraphic and structural relationships through geological and gammaespectrometry analysis in the interface between the São Francisco Craton and the Araçuaí Orogen (Santa Rita Anticline, Minas Gerais, Brazil); Geonomos, v.27, pp. 46-59.
Heilbron, M., Cordani, U.G. and Alkmim, F.F., 2017 - The São Francisco Craton and Its Margins; in Heilbron, M., Cordani, U.G. and Alkmim, F.F., (Eds.), São Francisco Craton, Eastern Brazil, Tectonic Genealogy of a Minature Continent, Springer Regional Reviews, pp. 3-13.
Lana, C., Alkmim, F.F., Armstrong, R., Scholz, R., Romano, R. and Nalini, H.A., 2913 - The ancestry and magmatic evolution of Archaean TTG rocks of the Quadrilátero Ferrífero province, southeast Brazil; Precambrian Research, v,231, pp. 157-173.
Martins de Sousa, D.F., Oliveira, E.P., Amaral, W.S. and Baldim, M.R., 2020 - The Itabuna-Salvador-Curaçá Orogen revisited, São Francisco Craton, Brazil: New zircon U-Pb ages and Hf data support evolution from Archean continental arc to paleoproterozoic crustal reworking during block collision; Journal of South American Earth Sciences, v.104, 68p. doi.org/10.1016/j.jsames.2020.102826.
Misi, A., Kaufman, A.J., Azmy, K., Dardenne, A., Sial, A.N. and Oliveira, T.F., 2011 - Neoproterozoic successions of the São Francisco Craton, Brazil: the Bambuí, Una, Vazante and Vaza Barris/Miaba groups and their glaciogenic deposits; Chapter 48, in Arnaudi, E., Halverson, E. and Shields-Zhou, G., (Eds.), The Geological Record of Neoproterozoic Glaciations. Geological Society, London, Memoirs, v.36, pp. 509-522.
Moreira, H., Seixas, L., Storey, C., Fowler, M., Lasalle, S., Stevenson, R. and Lana, C., 2018 - Evolution of Siderian juvenile crust to Rhyacian high Ba-Sr magmatism in the Mineiro Belt, southern São Francisco Craton; Geoscience Frontiers, v.9, pp. 977-995.
Neves, S.P., 2021 - Comparative geological evolution of the Borborema Province and São Francisco Craton (eastern Brazil): Decratonization and crustal reworking during West Gondwana assembly and implications for paleogeographic reconstructions; Precambrian Research, v.355, 23p. doi.org/10.1016/j.precamres.2021.106119.
Nutman, A.P., Cordani, U.G. and Sabate, P., 1994 - SHRIMP U-Pb ages of detrital zircons from the early Proterozoic Contendas-Mirante supracrustal belt, São Francisco Craton, Bahia, Brazil; Journal of South American Earth Sciences, v.7, pp. 109-114.
Peucat, J.J., Mascarenhas, J.F., Barbosa, J.S.F., Souza, S.L., Marinho, M.M., Fanning, C.M. and Leite, C.M.M., 2002 - 3.3 Ga SHRIMP U-Pb zircon age of a felsic metavolcanic rock from the Mundo Novo greenstone belt in the São Francisco craton, Bahia (NE Brazil); Journal of South American Earth Sciences, v.15, pp. 363-373.
Oliveira,E.P., Silveira, E.M., Söderlund, U. and Ernst, R.E., 2012 - U–Pb ages and geochemistry of mafic dyke swarms from the Uauá Block, São Francisco Craton, Brazil: LIPs remnants relevant for Late Archaean break-up of a supercraton; Lithos, v.174, pp. 308-322. doi.org/10.1016/j.lithos.2012.05.025.
Oliveira, E.P., Windley, B.F., McNaughton, N.J., Pimentel, M. and Fletcher, I.R., 2004 - Contrasting copper and chromium metallogenic evolution of terranes in the Palaeoproterozoic Itabuna–Salvador–Curaçá orogen, São Francisco craton, Brazil: new zircon (SHRIMP) and Sm-Nd (model) ages and their significance for orogen-parallel escape tectonics; Precambrian Research v.128, pp. 143-165.
Rolim, V.K., Rosi ère, C.A., Santos, J.O.S. and McNaughton, N.J., 2016 - The Orosirian-Statherian banded iron formation-bearing sequences of the southern border of the Espinhaço Range, Southeast Brazil; Journal of South American Earth Sciences, v.65, pp. 43-66.
Sial, A.N., Dardenne, M.A., Misi, A., Pedreira, V.P., Gaucher, C., Ferreira, P. Silva Filho, M.A., Uhlein, A., Pedrosa-Soares, A.C., Santos, R.V., Egydio-Silva, M., Babinski, M., Alvarenga, C.J.S., Fairchild, T.R. and Pimentel, M.M., 2009 - The São Francisco Palaeocontinent; Developments in Precambrian Geology, vol.3, Chapter 3, pp. 31-69. doi.org/10.1016/S0166-2635(09)01603-X.
Souza-Oliveira, J.S., Peucat, J.S., Barbosa, J.S.F., Correa-Gomes, L.C., Cruz, S.C.P., Leal, A.B.M. and Paquette, J.-L., 2014 - Lithogeochemistry and geochronology of the subalkaline felsic plutonism that marks the end of the Paleoproterozoic orogeny in the Salvador-Esplanada belt, São Francisco craton (Salvador, state of Bahia, Brazil); Brazilian Journal of Geology, v.44, pp. 221-234.
Spreafico, R.R., Barbosa, J.S.F., Barbosa, N.S. and Moraes, A.M.V., 2019 - Tectonic evolution of the Neoarchean Mundo Novo greenstone belt, eastern São Francisco Craton, NE Brazil: Petrology, U-Pb geochronology, and Nd and Sr isotopic constraints; Journal of South American Earth Sciences, v.95, 30p. doi.org/10.1016/j.jsames.2019.102296.
Student Chapter of the Federal University of Rio Grande do Sul, 2019 - Field trip 2019 Bahia magmatic deposits; Online Report https://www.segweb.org/pdf/students/student-chapters/federal-university-of-rio-grande-do-sul-ufrgs/Field-Trip-Report.pdf, 42p.
Teixeira, W., Ávila, C.A., Dussin, I.A. and Bongiolo, E.M., 2022 - U-Pb provenance fingerprints of metavolcanic-sedimentary successions of the Mineiro belt: Proxies for the continuity of plate tectonics through the Paleoproterozoic; Geoscience Frontiers, v.13, 27p. doi.org/10.1016/j.gsf.2021.101293.
Teixeira, W., Ávila, C.A., Dussin, I.A., Corrêa Neto A.V., Bongiolo, E.M., Santos, J.O. and Barbosa, N.S., 2015 - A juvenile accretion episode (2.35-2.32 Ga) in the Mineiro belt and its role to the Minas accretionary orogeny: Zircon U-Pb-Hf and geochemical evidences; Precambrian Research, v.256, pp. 148-169.
Teixeira, J.B.G., Silva, M.G., Misi, A., Cruz, S.C.P. and Sá, J.H.S., 2010 - Geotectonic setting and metallogeny of the northern São Francisco craton, Bahia, Brazil; Journal of South American Earth Sciences, v.30, pp. 71-83.
Zincone, S.A., Barbuena, D., Oliveira, E.P. and Baldim, M.R., 2017 - Detrital zircon U-Pb ages as evidence for deposition of the Saúde Complex in a Paleoproterozoic foreland basin, northern São Francisco Craton, Brazil; Journal of South American Earth Sciences, v.79, pp. 537-548.
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MANTIQUEIRA PROVINCE

The Mantiqueira Province is a NNE-trending Neoproterozoic orogenic system that follows the Brazilian coast from the southern edge of the northeastern São Francisco craton at ~16°S, for ~3000 km to southern Uruguay at ~33°S (Almeida et al., 1981). To the NW it is bounded by the São Francisco Craton, the cratonic Paranãpanema Block and the intervening Brasilia Belt. Prior to the opening of the South Atlantic Ocean, it, and a temporally equivalent belt along the African coast opposite, separated the Congo and São Francisco Craton-Paranãpanema Block. It represents a protracted sequence of orogenic events related to the assembly of West Gondwana, and comprises, from north to south, the Araçuaí, Ribeira, and Dom Feliciano orogens. These orogens have differing characteristics but merge along 'strike'. The Araçuaí Orogen, for example, contains an inboard extensional succession followed by a contractional event that produced a magmatic arc in the east. The Ribeira and Araçuaí orogens are separated by a structural 'pinchout' where the extensional sequence is absent, although the volcanic arc, which is more outboard, appears to continue between the two orogens that are described individually in more detail below. The equivalent West Congo Orogen on the African side of the Atlantic Ocean includes an extensional sequence temporally and lithologically equivalent to that of the Araçuaí orogen and over the São Francisco Craton, but lacks ophiolites or orogenic granites (e.g., Alkmim et al., 2006).

ARAÇCUAÍ FOLD BELT

The Araçuaí Orogen represents a Neoproterozoic extensional basin developed on the south-eastsern margin of the São Francisco Craton, separating it from the West Congo Craton prior to the separation of Africa from South America in the Mesozoic. Along the western fringe of the belt, it overlies the Espinhaço Supergroup, an interconnected, branched set of Palaeo- to Mesoproterozoic terrestrial to shallow marine rift-sag aulacogens, the chief of which are the Espinhaço, Paramirim and Pirapora rift basins that incised the São Francisco Craton and its margins. These sequences evolved from ~1.75 to 1.1 Ga through three extensional rift and rift-sag episodes. In the north and west, the Neoproterozoic sequence laps onto and thins to a shallower equivalent sequence over the Palaeoproteozoic and Archaean basement of the craton. The Neoproterozoic sequence comprises the Tonian to Edicaran rift-passive margin Macaúbas Group, and the overlying syn-orogenic Salinas Formation.
The distribution, tectonics and lithologies of the Espinhaço Supergroup as exposed on the transition between the Araçuaí Fold Belt and the São Francisco Craton are described in some detail in the appropriate section of the description of the latter, above.
The Macaúbas Group represents an areally extensive, and up to 10 km thick sedimentary succession that is exposed along most of the northern and western margins of the Araçuaí Belt and has been metamorphosed to under greenschist to amphibolite facies. The sequence has been involved in at least three evolutionary stages, that are in part associated with distinct episodes of anorogenic magmatism (Kuchenbecker et al., 2015), and are divided into three succession, as follows:
i) Lower, pre-glacial sequence, a Tonian rift succession accumulated in a continental to shallow marine regime between ~900 and 750 Ma (Kuchenbecker et al., 2015). Onset of extension is marked by a bimodal magmatic event comprising the 930 to 905 Ma Pedro Lessa mafic dykes; the ~875 Ma A-type Salto da Divisa Suite granites; and the Pedra Preta Amphibolite. These magmatic rocks occur as either intrusions into the basement and the Espinhaço Supergroup or with the basal units of the sequence. The succession comprises from the base, the Capelinha Formation, composed of garnet, staurolite and/or kyanite schists, quartz-schists and quartzites with interbedded ~957 Ma tholeiitic metabasalts towards the base; Matão Formation, fluvial to shallow marine breccias, conglomerates and sandstones deposited during a transgressive episode; Duas Barras Formation, up to 100 m of sandstones and rare conglomerate containing variable mica, feldspar, iron oxide and lithic fragments; Domingas Formation, which is only found to the west, on the craton margin, composed of siltstones, mudstones and large lenses of stromatolitic dolomite reflecting a shallow platformal environment; and the Rio Peixe Bravo Formation, only found to the east, where it is an up to 700 m thick, composed of micaceous, ferruginous and/or feldspathic sandstone, pelites and rare clast-supported conglomerates.
ii) Middle, glaciogenic marine sequence, corresponding to the global Sturtian glaciation, accompanying a renewed rifting event at the beginning of the Cryogenian, and including the diamictite-rich packages of the Serra do Catuni Formation, a massive, typically glacial diamictite with minor sandstone and pelite intercalations; the Nova Aurora Formation, a distal equivalent of the Serra do Catuni Formation (Noce et al., 1997; Pedrosa-Soares et al., 2011) which comprises diamictites, sandstones and rare pelites. It includes thick layers of Rapitan-type diamictitic iron formation; and Lower Chapada Acauã Formation, made up of stratified diamictite, graded sandstones and pelites, representing a cyclic succession of debris flows and sandy to muddy turbidites (Pedrosa-Soares et al., 1992; Uhlein et al., 1999, 2007; Martins 2006).
iii) Upper, post-glacial succession, in a regime where the previous rift evolved into a passive margin, as indicated by ophiolitic remnants in the central part of the orogen. This succession, which contains the only Cryogenian detrital zircons in the group, is diamictite-free, and comprises: the Upper Chapada Acauã Formation, which is made up of sandstone and pelite deposited in a continental shelf setting; and grades laterally into the Ribeirão da Folha Formation, which includes distal passive margin and ocean floor deposits of fine-grained turbidites and chemical sediments which include chert, banded iron formation and limestone, with associated metamafic and meta-ultramafic rocks. The latter yield ocean-floor lithochemical signatures with Ediacaran magmatic crystallisation U-Pb ages, suggesting oceanic spreading and extension at least from ~660 to 600 Ma (Queiroga et al., 2007; Queiroga 2010).
The Salinas Formation is interpreted to be a syn-orogenic, 1600 m thick succession of turbiditic wackes, sandstones, pelites and conglomerates that have been metamorphosed to greenschist to amphibolite facies. They are restricted to the internal core of the fold belt, covering or in tectonic contact with the distal facies of the Chapada Acauã and Ribeirão da Folha formations. They were deposited between 548 and 520 Ma., coeval with the Bambuí Group in the São Francisco Basin over the craton to the west (Alkmim et al., 2017).
The Macaúbas Basin is interpreted to have progressively opened during the deposition of the Macaúbas Group and Salinas Formation as an embayment, open to the south, bounded to the east by the Congo Craton, and to the north and west by the São Francisco Craton, with the two being joined in the north. During the period of extension, the São Francisco Craton, which formed a peninsular to the west, opened scissor like with a hinge to the north, where deposition was within the north-tapering Paramirim Aulacogen, while to the south, by the top pf the post-glacial Macaúbas succession, a wide oceanic crust floored gulf had opened (Alkmim et al., 2017). At ~630 Ma, the extensional regime began to be inverted, with contraction being accommodated by eastward dipping subduction of the oceanic plate in the south below the Congo Craton and forming the major volcano-plutonic Rio Doce Magmatic Arc on the edge of the latter. This contraction mirrored the earlier extension, with a pivot in the north, and maximum contraction to the south, referred to as "Nutcracker tectonics" (Alkmim et al., 2017; Melo et al., 2017; Alkmim et al., 2006). The arc and succeeding extensive late to post collisional intrusions formed a crystalline core, intruded into a suite of high grade metamorphic migmatitic granulite and migmatitic kinzigite (a coarse granulite facies meta-pelite/Al-rich paragneiss) overlapping its eastern margins. These latter high grade metamorphic rocks are considered to be derived from Macaúbas Group-Salinas Formation protoliths. To the west of the crystalline core, the degree of metamorphism decreases westward to and onto the São Francisco Craton.
The Rio Doce Magmatic Arc forms an ~500 km long, linear north-south belt of volcanic and intrusive rocks in the core of the Araçuaí Orogen. The arc is made up of the Rio Doce Group volcano-sedimentary sequence and the coeval 630 to 580 Ma plutonic G1 supersuite. The Rio Doce Group comprises, from the base, the Palmital do Sul and Tumiritinga formations which mostly comprise pelitic schists to paragneisses, interbedded with proximal dacitic to rhyolitic meta-volcanic and explosive meta-volcaniclastic rocks dated at 595 ±13 and 584 ±5 Ma (zircon U-Pb); the overlying São Tomé Formation mainly includes psammitic to pelitic meta-turbidites with lenses of calc-silicate rocks, indicating a distal marine setting with a maximum depositional age of ~594 Ma and an arc-related lithochemical signature. The uppermost João Pinto Formation is predominantly quartz sandstones and micaceous to feldspathic sandstones, with a maximum sedimentation age of ~620 Ma, representing a fluvial to continental shelf setting (Novo et al., 2018). The G1 Supersuite is a calc-alkaline, magnesian, I-type pre-collisional rock-assemblage, mostly composed of tonalite to granodiorite, minor monzonitic rocks and diorite to gabbronorite, frequently containing dioritic to mafic enclaves, and their metamorphosed equivalents. The Rio Doce Magmatic Arc is regarded as a temporal correlative of the Salinas Formation (Gonçalves-Dias et al., 2016).
The Rio Doce Magmatic Arc is succeeded by and/or overlaps another 4 granitoid supersuites as follows: G2 Supersuite, a series of batholiths and stocks of syn- to late-collisional S-type peraluminous granites intruded between 590 and 540 Ma. These are the most voluminous and are found to the east and north of the Rio Doce Magmatic Arc. They are mostly biotite-garnet syenogranite to alkali-feldspar granite with minor monzogranite to tonalite, rich in garnet, and garnet-two-mica granite, locally with sillimanite; G3 Supersuite, late- to post-collisional, 545-500 Ma alkali feldspar granite to syenogranite with cordierite and/or garnet, poor to free of biotite, occurring as undeformed dykes and small stocks, free of the regional foliation, mostly cutting migmatites and G2; G4 Supersuite, are more restricted, being confined to a narrow zone to the north and NW of the northern extremity of the Rio Doce Magmatic Arc. They are characterised by post-collisional granites emplaced between 530 and 500 Ma, mainly leucogranites to two-mica granites generally with garnet, pegmatoid granite and minor biotite granite occurring as balloon shaped plutons, with minor sill like bodies, generally free of any regional deformation fabric; G5 Supersuite, 520 to 480 Ma high-K metaluminous A- and I-type granitoids, mainly alkali feldspar granite to granodiorite and corresponding orthopyroxene-bearing (charnockitic) rocks, with minor enderbite and gabbronorite. Rich in magma mingling textures with mafic to intermediate enclaves. They area generally co-extensive with G2, extending further to the east, although individual batholiths are smaller (Soares et al., 2020; Pedrosa-Soares et al., 2011).
The northeastern and eastern sections of the high grade crystalline core of the orogen is occupied by the Neoproterozoic Jequitinhonha and Nova Venécia complexes respectively. These complexes have been intruded by the four granitoid supersuites, G2 to G5 inclusive, and are composed of granulite facies metamorphic suites and migmatites.
The Jequitinhonha Complex occupies the northeastern section of the Araçuaí Orogen, separated from the Nova Venécia Complex and the Macaúbas Group-Salinas Formation to the south and west respectively by extensive exposures of late- and post collisional G2 to G5 granitoid supersuites. It is composed of metasedimentary Al-rich (kinzigitic) paragneisses with decametric intercalations of graphite gneisses and quartzites, and centimetric to metric lenses of calc-silicate rocks. Detrital zircon ages and geochemistry support a correlation with the the passive margin units of the upper Macaúbas Group, and an ensialic northern termination of the gulf during the Neoproterozoic. The provenance of the protolithic sequence is indicated as Archaean to Palaeoproterozoic São Francisco Craton and Mesoproterozoic Espinhaço Supergroup rocks. Metamorphism of the complex is estimated to have occurred between 580 and 545 Ma at peak conditions 850°C and 7 Kbar to produce amphibolite to granulite facies transition rocks (Gonçalves-Dias et al., 2016). An initial partial melting of the paragneiss produced biotite-garnet S-type granite, locally rich in cordierite, representing the G2 Supersuite, followed by a second melting episode generating thin dykes and patches of unfoliated garnet-cordierite leucogranite representing the G3 supersuite (Pedrosa-Soares et al., 2011).
The Nova Venécia Complex in the east comprises migmatitic granulite facies metasediments and granitoids interpreted to have protoliths of meta-greywackes containing between 15 and 50% clay and silt components. These rocks were possibly formed as turbidite flows in a back-arc basin from the Rio Doce Magmatic Arc to the west, and as such are probably younger than the Jequitinhonha Complex. The maximum sedimentation age of the complex is 606 Ma, whilst it is intruded by syn-collisional G2 plutons at 593 Ma (Richter et al., 2016). Thermodynamic modelling indicates two major heat pulses at ~593 to 560 and 523 to 495 Ma, with peak metamorphism at 850 to 750°C and 5.30 to 7.50 Kbar under granulite-facies conditions from 575 to 560 Ma. This age temporally overlaps the crystallisation of the G4 and G5 supersuites. Preserved retrograde stability assemblages of garnet, cordierite and orthopyroxene suggest conditions of formation at ~800 to 640°C and 6.00 to 4.50 Kbar. There is evidence to suggest significant exhumation and cooling occurred subsequently to peak metamorphism, but prior to the G5 thermal event at 520 to 480 Ma which was the result of the tectonic collapse of the orogen (Richter et al., 2016).
During the contractional stage of the Araçuaí Orogen, reflected by the Rio Doce Magmatic Arc and the G1 to G2 supersuites, thin skinned deformation across the Serra do Espinhaço Thrust and Fault Belt accommodate west vergent thrusting of the Macaúbas Group over the São Francisco Craton. This fold and thrust belt exposes cores of Archaean and Espinhaço Supergroup as the Porteirinha Block and Espinhaço Range to its south. In the NE of the Orogen, another fold and thrust belt accommodates both NE vergent thrusting of the Jequitinhonha Complex over the craton and differential dextral translation during thrusting on the Serra do Espinhaço Thrust and Fault Belt (Oliveira et al., 2021; Alkmim et al., 2017).
The southwestern segment of the Araçuaí Orogen is occupied by the Guanhães Block, which, as described above, is the reworked Archaean basement to both the Espinhaço Supergroup and the Macaúbas Group rift successions. Remnants of these sequences are locally preserved, after the block was uplifted, eroded and thrust west on the thin-skinned Neoproterozoic Espinhaço fold and thrust belt. In doing so, it overrode the Espinhaço Supergroup sequence and the eastern margin of the São Francisco Craton. To the east, it is fringed by the fault bounded forearc accretionary wedge over the subduction zone responsible for the Rio Doce Magmatic Arc.
The section of the Macaúbas Basin preserved on the African side of the South Atlantic Ocean is predominantly composed of high grade metamorphic rocks, without significant magmatic rocks or evidence of oceanic crust basement (Fossen et al., 2020).
The evolution of the crystalline core and surrounds is interpreted to have involved up to 5 geodynamic stages: Stage 1 a rift-phase between 1000 and 660 Ma whereby accompanying crustal attenuation resulted in asthenospheric upwelling and decompression melting, which in turn produced anorogenic magmas (e.g. Pedrosa-Soares and Alkmim 2011; Silva et al., 2008; Queiroga et al., 2007); Stage 2 inversion through commencement of contraction and the formation of supra-subduction pre-collisional magmas (Pedrosa-Soares et al., 2011; Gradim et al., 2014); Stage 3 syn-collision, that corresponds to thin skinned deformation and thrusting of the Macaúbas Group and Espinhaço Supergroup, including basement such as the Guanhães Block, overriding the São Francisco Craton; Stage 4 late to post-collisional, between 560 and 535 Ma, with the break-off of the subduction slab, delamination and detachment of section of the sub-crustal lithospheric mantle below the crystalline core, and renewed asthenospheric upwelling and decompression melting; Stage 5 post-collisional tectonic collapse between 520 and 490 Ma (Pedrosa-Soares et al., 2006, 2008, 2011).
It should be noted that Cavalcante et al. (2019) advance observations that suggest the "Nutcracker tectonics" theory has weaknesses and that the São Francisco-Congo connection was broken by a n orogenic corridor along the current Atlantic margin with major dextral translation along this break that accommodated the extension and closure postulated.
Fossen et al. (2020) and Fossen, Cavalcante and Almeida (2017) mount a convincing argument that the Macaúbas Basin between the São Francisco and Congo craton, while opening as a wide intracratonic rift, did not advance to the formation of intervening oceanic crust that was subsequently subducted during the Brasiliano-Pan African Orogeny. Rather, they suggest there is sufficient evidence to suggest extension did not proceed beyond crustal attenuation, and the rare mafic rocks interpreted as ophiolites are rift-related mafic magmatic rocks emplaced during the final stages of that attenuation. They suggest that the inversion of the rift during the orogeny resulted in imbrication and widespread anatexis and migmatisation that produced the magmatic rocks of the Rio Doce Magmatic Arc and the metamorphic assemblages of the crystalline core. This argument is discussed by those authors in the papers cited below.

Araçuaí Fold Belt References
Alkmim, F.K., Kuchenbecker, M., Reis, H.L.S. and Pedrosa-Soares, A.C., 2017 - The Araçuaí Belt; Chapter 14 in M. Heilbron et al., (eds.), 2017, São Francisco Craton, Eastern Brazil; Springer International Publishing, Switzerland, pp. 255-276.
Alkmim, F.K., Marshak, S., Pedrosa-Soares, A.C., Peres, G.G., Cruz, S.C.P. and Whittington, A., 2006 - Kinematic evolution of the Araçuaí-West Congo orogen in Brazil and Africa: Nutcracker tectonics during the Neoproterozoic assembly of Gondwana; Precambrian Research; v.149, pp. 43-64.
Bitencourt, C.N., Cruz, S.C,P., Cruz, V.d,A., Pedrosa-Soares, A.C., Paquette, J.L., Alkmim, A.R. and Barbosa, J.S.F., 2019 - Rifting events in the southern sector of the Paramirim Aulacogen, NE Brazil: New geochronological data and correlations for the São Francisco - Congo paleocontinent; Precambrian Research, v.326, pp. 417-446.
Braga, F.C.S., Rosiére, C.A., Santos, J.O.S., Hagemann, S.G., Danyushevsky, L. and Salles, P.V., 2021 - Geochemical and tectonic constraints on the genesis of iron formation-hosted magnetite-hematite deposits at the Guanhães Block(Brazil) by contact metasomatism with pegmatite intrusions; Ore Geology Reviews, v.129, 23p.
Cavalcante, C., Fossen, H., Almeida, R.P., Hollanda, M.H.B.M. and Egydio-Silva, M., 2019 - Reviewing the puzzling intracontinental termination of the Araçuaí-West Congo orogenic belt and its implications for orogenic development; Precambrian Research; v.322, pp. 85-98.
Cruz, S.C.P. and Alkmim, F.F., 2006 - The Tectonic interaction between the Paramirim Aulacogen and the Araçuaí Belt, São Francisco craton region, Eastern Brazil; Anais da Academia Brasileira de Ciências, v.78(1), pp. 151-173.
Egydio-Silvaa, M., Vauchez, A., Fossen, H., Cavalcante, G.C.S. and Xavier, B.C., 2018 - Connecting the Araçuaí and Ribeira belts (SE - Brazil): Progressive transition from contractional to transpressive strain regime during the Brasiliano orogeny - Journal of South American Earth Sciences, v.86, pp. 127-139.
Dias, T.G., Caxito, F.A., Pedrosa-Soares, A.C., Stevenson, R., Dussin, I., Silva, L.C., Alkmim, F. and Pimentel, M., 2016 - Age, provenance and tectonic setting of the high-grade Jequitinhonha Complex, Araçuaí Orogen, eastern Brazil; Brazilian Journal of Geology, v.46, pp. 199-219.
Heilbron, M. and Girão, R., 2020 - Proterozoic to Ordovician geology and tectonic evolution of Rio de Janeiro State, SE-Brazil: insights on the central Ribeira Orogen from the new 1:400,000 scale geologic map; Brazilian Journal of Geology; v.50, 25p.
Fossen, H., Cavalcante, G.C., Konopásek, J., Meirae, V.T., Paes de Almeida, R., Holland, M.H.B.M. and Trompette, R., 2020 - A critical discussion of the subduction-collision model for the Neoproterozoic Araçuaí-West Congo orogen; Precambrian Research, v.343, doi.org/10.1016/j.precamres.2020.105715.
Fossen. H., Cavalcante, G.C. and Almeida, R.P., 2017 - Hot versus cold orogenic behavior: Comparing the Araçuaí-West Congo and the Caledonian orogens. Tectonics, v.36, pp. 2159-2178. https://doi.org/10.1002/2017TC004743.
Kuribara, Y., Tsunogae, T., Santosh, M., Takamura, Y., Costa, A.G. and Rosière, C.A., 2019 - Eoarchean to Neoproterozoic crustal evolution of the Mantiqueira and the Juiz de Fora Complexes, SE Brazil: Petrology, geochemistry, zircon U-Pb geochronology and Lu-Hf isotopes; Precambrian Research, v.323, pp. 82-101. doi.org/10.1016/j.precamres.2019.01.008.
Melo, M.G., Stevens, G., Lana, C., Pedrosa-Soares, A.C., Frei, D., Alkmim, F.F. and Alkmin, L.A., 2017 - Two cryptic anatectic events within a syn-collisional granitoid from the Araçuaí orogen (southeastern Brazil): Evidence from the polymetamorphic Carlos Chagas batholith; Lithos, v.277, pp. 51-71.
Novo, T.A., Pedrosa-Soares, A., Vieira, V.S., Dussin, I. and Silva, L.C., 2018 - The Rio Doce Group revisited: An Ediacaran arc-related volcanosedimentary basin, Araçuaí orogen (SE Brazil); Journal of South American Earth Sciences, v.85, pp. 345-361.
Oliveira, R.G., Martins, M., Queiroga, G., Souza, M.E.S., Lana, C., Alkmim, A.R., Silva, M.A.L., Bueno, C. and Linhares, D., 2021 - Sedimentary provenance and role of tectonic inheritance on the control of the Macaúbas group, eastern margin of São Francisco Craton (SE Brazil); Journal of South American Earth Sciences, v.109, doi.org/10.1016/j.jsames.2021.103210.
Pacheco, F.E.R.C., Caxito, F.A., Souza, M.E., Bento, C.C., Pedrosa-Soares, A. and Lana, C.C., 2023 - Detrital zircon U–Pb analysis constrain the depositional age and provenance of Cryogenian glacial successions of the Macaúbas group in the northeastern Araçuaí orogen, eastern Brazil; Journal of South American Earth Sciences, v.121, doi.org/10.1016/j.jsames.2022.104122.
Pedrosa-Soares, A.C., Noce, C.M., Wiedemann, C.M. and Pinto, C.P., 2001 - The Araçuaí-West-Congo Orogen in Brazil: an overview of a confined orogen formed during Gondwanaland assembly; Precambrian Research, v.110, pp. 307-323. Richter, F., Lana, C., Stevens, G., Buick, I, Pedrosa-Soares, A.C., Alkmim, F.F. and Cutts, K., 2016 - Sedimentation, metamorphism and granite generation in a back-arcregion: Records from the Ediacaran Nova Venécia Complex (Araçuaí Orogen, Southeastern Brazil); Precambrian Research, v.272, pp. 78-100.
Soares, C, Queiroga, G., Pedrosa-Soares, A., Gouv&eacirc;a, L.P., Valeriano, C.M., Melo, M.G., Marques, R. and Delicio, R., 2020 - The Ediacaran Rio Doce magmatic arc in the Araçuaí - Ribeira boundary sector, southeast Brazil: Lithochemistry and isotopic (Sm-Nd and Sr) signatures; Journal of South American Earth Sciences, V.104, 18p.

RIBEIRA BELT

The Araçuaí Belt passes directly into the Ribeira Belt to the SW. Both are part of the greater NE-SW to ENE-WSW trending Mantiqueira Province, a composite orogenic system distributed along the Brazilian Atlantic coast that extends from the northeastern São Francisco Craton to Uruguay. The evolution of the Ribeira Belt has been interpreted to represent the progressive accretion of two different magmatic arc systems, an inner and outer, onto the southeastern and southern margin of the São Francisco Palaeocontinent during the Neoproterozoic.
The Occidental terrane, encompassing the reworked basement and cover of the passive margin of the São Francisco Craton. This terrane is up to 100 km wide and comprises three major litho-tectonic units:
• Older basement reworked during the Palaeoproterozoic basement, intruded by bimodal Mesoproterozoic magmatic rocks (Heilbron et al., 1998, 2010, Noce et al., 2007, Degler et al., 2018);
• Two thrust packages, a proximal and distal suite to the NW and SE respectively. The proximal package is composed of a Neoproterozoic metasedimentary sequence, the Raposos Group, correlated with the Andrelândia Group found to the west in the Brasilia Belt (Paciullo et al., 2000). This sequence tectonically overlies the basement and comprises a basal suite of banded psammitic gneisses with quartzites, pelitic schist and amphibolite intercalations, followed by a regressive succession of quartzites characterised by green muscovite, succeeded by a transgressive succession of graphite-rich grey schists and feldspathic quartzites. The overlying Serra do Turvo Sequence is composed of pelitic schists and gneisses, followed by the uppermost unit of plagioclase-rich schists and gneisses (Heilbron et al., 2019). Age dating of intercalated mafic rocks suggest the Raposos Group was deposited after ~1.0 to 0.9 Ga in the Tonian (Valeriano et al., 2004, Valladares et al. 2004) but has ~680 Ma detrital zircons in the upper units (Belém et al., 2011; Frugis and Campos Neto, 2018; Westin and Campos Neto 2013). The distal upper thrust package comprises the Juiz de Fora Complex, which has been subjected to intense tectonic shuffling and high pressure metamorphism granulite facies conditions between 640 and 600 Ma (Coelho et al., 2017, Heilbron et al., 2017, Trouw et al., 2013). The following lithologies have been identified, orthogranulites with amphibolite facies retrograde mylonites; banded amphibolite facies orthogneisses; metasedimentary granulites (kinzigite); and an intrusive garnet charnockite plutons. All of these are older than 1.8 Ga when they were first metamorphosed. They are interleaved with amphibolite to granulite facies meta-sediments of probable Meso- to Neoproterozoic age, possibly equivalents of the Raposos Group. Petrological data indicate high temperatures and intermediate to low lithostatic pressure conditions for the Palaeoproterozoic granulite facies metamorphism, prior to the Neoproterozoic metamorphism and deformation (Heilbron et al>, 1998).
• syn- to late-collisional Neoproterozoic granitoid rocks which intrude all of the above.
The Inner Magmatic Arc System was developed between ~650 and 595 Ma on a Palaeoproterozoic microcontinent, which collided with, and was overthrust onto, the southeastern reworked passive margin of the São Francisco Paleocontinent at ~600 Ma. This latter event was more or less coeval with the emplacement of syn-collisional granitoid rocks into the lower plate. The arc is preserved as dismembered sheets within the different tectonic terranes of the Ribeira Belt, overriding the margin of the São Francisco Paleocontinent and has been modified by late orogenic (D3) folding (Heilbron et al., 2004, 2017) and by Phanerozoic brittle faults. The northeastern end of this arc has been interpreted to connect with the Rio Doce Magmatic Arc in the Araçuaí Orogen to the NE (Tedeschi et al., 2016). The arcs comprise a suite of plutonic bodies, including granodiorites, tonalites, diorites, gabbros and monzonitic series rocks, such as monzogabbros, monzodiorites and monzonites. Alkaline rocks of syenitic composition may occur locally (Heilbron et al. , 2012). All have been subjected to the regional Neoproterozoic metamorphic overprint, being more intense along the lowermost part of the arc system. Textures reflect progressive granulite facies metamorphism, represented by pyroxene growth from hornblende and biotite, and retrograde textures consisting of biotite and hornblende rims around pyroxene crystals and within cleavage seams. Geochemical signatures and distribution are interpreted to corroborate the advance of the arc over a SE dipping subducting oceanic plate to collide with the passive margin to the NW. Individual plutons indicate crystallisation ages of between ~650 and 600 Ma in the late Cryogenean to Ediacaran, with a high-grade metamorphic overprint between ~600 and 582 Ma (Heilbron et al., 2020).
The Outer Magmatic Arc System has a relatively more juvenile signature and exhibits a complete evolution from an intra-oceanic setting to a continental primitive arc. This evolution has been subdivided into two stages: a Tonian to Cryogenian and a Late Tonian to Ediacaran stage (Peixoto et al., 2017; Heilbron et al., 2017). It occupies the Oriental Terrane of the Ribeira belt, which comprises a 500 x 200 km linear domain that extends along the coastal belt of Rio de Janeiro and southern Espírito Santo states, between the towns of Vitória and Parati. The older and more juvenile Tonian to Cryogenian Serra Prata granitoid rocks comprise metaluminous calc-alkaline hornblende-biotite-tonalites, commonly associated with lenses of foliated coarse-grained amphibolite of dioritic composition. They exhibit varied deformation features ranging from quite homogenous and granoblastic to well-foliated and locally mylonitic orthogneisses. The most common lithologies are mesocratic grey hornblende-biotite-orthogneiss, pale grey biotite-orthogneiss, and leucocratic biotite-orthogneiss. The hornblende- and biotite-orthogneisses vary from dioritic → tonalitic → granodioritic, and have a gradational contact with the leucogneisses which are mostly granitic in composition. The crystallisation ages of the orthogneisses and amphibolites is between 859 and 839 Ma. The orthogneisses are accompanied by coarse grading to fine-grained, migmatitic and foliated biotite-muscovite paragneiss with centimetre scale banding of alternating felsic layers rich in quartz, microcline, plagioclase, biotite and muscovite, with mafic layers rich in hornblende and biotite. These are interpreted to reflect a fore-arc setting and represent psammo-pelitic protoliths with some volcaniclastic components. A coeval, early, possibly back-arc shallow carbonatic platform with mafic magmatism is also developed, composed of coarse-grained calcitic marbles with centimetre to metre thick layers of amphibolite and calc-silicate rocks (Heilbron et al., 2020). The Cryogenean to Early Ediacaran Rio Negro section of the arc occupies the western half of the Oriental Terrane, and varies from a few, up to 40 km in width, laterally overlapping the Serra Prata section of the arc. It consists of orthogneiss of plutonic origin, mainly tonalitic to trondhjemitic batholiths, with minor hornblende-gabbro and quartz-diorite stocks. These orthogneisses have several main geochemical associations that include a low-to medium-K, a high-K and a shoshonitic association as well as meta-diorites and gabbros. Deformation and metamorphic overprint resulted in textures that vary from almost isotropic to strongly foliated. The relationship between the orthogneisses and associated high-grade metasedimentary rocks of the São Fidelis Group immediately to the SE, suggest a coeval development. The latter comprises high-grade metasedimentary psammo-pelitic to pelitic rocks with quartzite, calc-silicate and marble layers. The Rio Negro orthogneisses yield a crystallisation age of ~790 Ma in one tonalite sample, although the most common ages are from 635 to 607 Ma, whilst metamorphic rims surrounding magmatic cores give monazite ages of between ~604 and 567 Ma (Tupinambáa et al., 2012; Heilbron and Machado, 2003; Peixoto et al., 2017). The Outer Magmatic Arc System is interpreted to represent intraoceanic arcs that diachronously approached, collided with and overrode the Inner Magmatic Arc System over a SE dipping subduction zone, between 860 and 567 Ma.
Whilst Heilbron et al. (2020) follow the accepted interpretation of the setting of the Ribeira Belt which assumes recurrent collision and accretion of a number of terranes against the São Francisco Craton after 600 Ma, Meira et al. (2019) provide an elegant alternative. They propose that the Ribeira Belt was an amalgamated terrane by 650 Ma, and perhaps as early as ~790 Ma when intracontinental basaltic and granitic magmatism intruded both 'magmatic arcs'. This event is taken to be related to the collision between the Paranãpanema Block (and/or Congo Craton) and the São Francisco Craton which inverted the Neoproterozoic basins of the Mantiqueira Province. They suggest the belt evolved as a weakened crustal sector that was thickened in an intracontinental environment at ~620 Ma (corresponding to the M1 metamorphism) followed by recurrent extensional and wrench tectonics at ~575 Ma (corresponding to the M2 metamorphism). They interpret the older M1 metamorphism to indicate burial of the metasedimentary successions to as much as 8.0 Kbar (~25 km depth) and amphibolite metamorphic facies conditions. This contractional regime, with concomitant crustal thickening, produced two foliations, S1 and S2 which are evident in both the 'Inner' and 'Outer' magmatic arcs, usually recorded by rootless isoclinal intrafolial microfolds. Tectonic relaxation and near isothermal decompression to ~3.0 Kbar (~10 km) and ~600 to 550°C characterises the subsequent M2 metamorphism accompanying crustal attenuation and asthenospheric upwelling. Wide dextral strike‐slip shear zones typify the D3 deformation phase (S3 mylonitic foliation) during the ensuing cooling and decompression stage. In the 'Outer Magmatic Arc System' however, M2 metamorphism involved heating with moderate decompression and peak conditions of ~750 to 650°C and ~4.0 to 6.0 Kbar (~12 to 18 km), followed by cooling and decompression. They suggest that heating to upper amphibolite metamorphic facies to which the rocks of 'Outer Magmatic Arc System' were subjected, caused widespread partial melting of the middle crust during decompression, forming migmates and peraluminous leucogranites. The low angle deformation fabric (S3 mylonitic foliation) associated with this metamorphic phase is interpreted as extensional crustal flow of molten middle crust (Meira et al., 2019).

Ribeira Belt References
Bento dos Santos, T.M., Tassinari, C.C.G. and Fonseca, P.E., 2015 - Diachronic collision, slab break-off and long-term high thermal flux in the Brasiliano-Pan-African orogeny: Implications for the geodynamic evolution of the Mantiqueira Province; Precambrian Research, v.260, pp. 1-22. 3182-3209. https://doi.org/10.1029/2018TC004959.
Heilbron, M., Oliveira, C., Lobato, M., Valeriano, C.M., Dussin, I., Dantas, E., Simonetti, A., Bruno, H., Corrales, F. and Socoloff, E., 2019 - The Barreiro suite in the central Ribeira Belt (SE-Brazil): a late Tonian tholeiitic intraplate magmatic event in the distal passive margin of the São Francisco Paleocontinent; Brazilian Journal of Geology, v.49, 21p. doi: 10.1590/2317-4889201920180129.
Heilbron, M., Duarte, B.P. and Nogueiro, J.R., 1989 - The Juiz De Fora Granulite Complex of the Central Ribeira Belt, SE Brazil: A Paleoproterozoic Crustal Segment Thrust During the Pan-African Orogeny; Gondwana Research, V.1., pp.373-381.
Heilbron, M., Valeriano, C.M., Peixoto, C., Tupinambá, M., Neubauer, F., Dussin, I., Corrales, F., Bruno, H., Lobato, M., Almeida, J.C.H. and Silva, L.G.E., 2020 - Neoproterozoic magmatic arc systems of the central Ribeira belt, SE-Brazil, in the context of the West-Gondwana pre-collisional history: A review; Journal of South American Earth Sciences, v.103, 23p. doi.org/10.1016/j.jsames.2020.102710.
Meira, V.T., Garcia‐Casco, A., Hyppolito, T., Juliani, C., & Schorscher, J.H.D., 2019 - Tectono‐metamorphic evolution of the Central Ribeira Belt, Brazil: A case of late Neoproterozoic intracontinental orogeny and flow of partially molten deep crust during the assembly of West Gondwana; Tectonics, v.38, pp.

BORBOREMA PROVINCE

The Borborema Province is bounded to the west by the Parnaíba Basin and concealed Parnaíba Block, while it defines the northern margin of the São Francisco Craton. It is a complex mosaic of Palaeoarchaean to early Mesoproterozoic basement fragments/domains and Neoproterozoic fold belts, separated by major regional shear zones. The structural framework exhibits a NE diverging fan-like distribution, consisting of an important network of shear zones that range from near NNE trending in the NE, to near east-west to SE in the SE. A variety of tectonic histories have been proposed to explain the current morphology of the province (Caxito et al., 2020). At one extreme it is hypothesised that all of these domains represent separate accreted exotic allochthonous lithospheric blocks that were amalgamated during the Neoproterozoic ~1000 to 920 Ma Cariris Velhos and ~ 625 to 510 Ma Brasiliano orogenies (e.g., Santos, 1996; Coney et al., 1980). At the other extreme, it is postulated the province involves the reworking of a single autochthonous block, which remained relatively stable from ~2.0 Ga before being affected by the opening and subsequent inversion of mainly intracontinental rift basins throughout the remainder of the Proterozoic (e.g., Neves 2003, 2018; Neves et al., 2006, 2009). In this second scenario, the metamorphism, deformation and magmatism associated with the Brasiliano Orogeny would have essentially been the result intracontinental processes, although locally, subduction and plate convergence may have played a part. This is consistent in part with the observation that some, if not most of the regional shear zones do not always separate domains of distinct geological or geophysical features (e.g., Neves and Mariano, 1999; Caxito et al., 2016; Oliveira and Medeiros, 2018). However, some of these shear zones appear to have been nucleated and developed at least in part along the sites of ancient inter-plate sutures (e.g., Padilha et al., 2014; Oliveira and Medeiros 2018). Others cut across and offset blocks with a distinctly similar nature and composition (Caxito et al., 2020).
Three main regional shear zones subdivide and limit the Borborema Province, dividing it into three major tectonic entities: the Northern, Transverse and Southern sub-provinces, each of which is further subdivided into internal alternating meta-igneous and meta-sedimentary domains, separated by other shear/fault zones (Almeida et al., 1976; Brito Neves 1983, Santos and Brito Neves 1984, Jardim de Sá et al., 1992, Santos et al., 2000, Brito Neves et al., 2000). These structures are the i). NE-trending Transbrasiliano (locally also known as the Sobral-Pedro) Shear Zone/Lineament that separates the NW corner of the Boroborema Province from the São Luís Craton affiliated Medio Coreaú Domain, most likely the eastern Garupi Belt that forms the southern margin of that craton; ii). the east-west trending, dextral Patos-(Campina Grande) Shear Zone that separates the Northern and Transverse sub-provinces; and, 150 km to the south, iii). the similarly east-west and dextral Pernambuco Shear Zone that separates the Transverse and Southern sub-provinces (Caxito et al., 2020; Fig. 1). The southern fringe of the Southern subprovince includes the Rio Preto, Riacho do Pontal and Sergipano Belts/Domains, that are described in more detail below.
Large parts of the Borborema Province, but mostly in the Northern Sub-province, are composed of Palaeoproterozoic basement, predominantly Rhyacian 2.25 to 2.05 Ga, but with restricted occurrences as old as 2.3 to 2.4 Ga in the Siderian. The Rhyacian basement is largely composed of orthogneisses and migmatites, considered to have resulted from the Transamazonian amalgamation of microcontinents and island arcs during a major accretionary/collisional event terminated at ~2 Ga (Neves, 2021). The orthogneisses range in composition from quartz-diorite to granite, but meta-ultramafics, meta-gabbros, amphibolites and metasedimentary rocks are locally significant (Neves, 2003).
The domains within the sub-provinces also include Archaean nuclei, the largest of which are ~100 km long. These domains, which are predominantly within the Northern Sub-province, include the i). 3.5 to 2.5 Ga Granjeiro Complex (Ancelmi 2016; Pitarello et al., 2019); ii). the 3.45 to 3.2 Ga São José do Campestre Massif which also contains 2.7 Ga alkaline intrusions (Dantas et al., 2004, 2013); iii). mafic to ultramafic rocks dated at ~3.7 to 3.5 Ga in the Rio Grade do Norte Domain (Santos et al., 2020); iv). the 2.8 to 2.7 Ga Tróia-Pedra Branca Massif towards the north in Ceará (Fetter et al. 2000; Ganade de Araújo et al. 2017) and v). part of the 3.2 Ga Cristalândia do Piauí Block in the Rio Preto Belt basement of the Southern Sub-province, which is accompanied by 2.7 to 2.5 Ga alkaline intrusions (Barros 2019). These basement nuclei are mainly composed of TTG orthogneiss and metasedimentary paragneiss and schist (Caxito et al., 2020).
The Rhyacian Transamazonian orogenesis was followed by a period of intermittent rifting and intraplate magmatic events between 1.78 and 1.50 Ga (Neves, 2021). The basement in the southern half of the Northern Sub-province is overlain by the Stratherian 1.8 to 1.7 Ga Orós-Jaguaribeano Belt meta-volcanosedimentary suite, which is largely restricted to the Northern Sub-province, and was deposited in an extensional setting (Caxito et al., 2020). The sedimentary facies of this sequence are now preserved as fault bounded slivers of gneiss, schist and quartzite, with associated marble/magnesite. The metavolcanic facies in the lower unit of the sequence are bimodal, with a predominance of felsic over mafic composition. In the Transverse Sub-province, similar, but younger 1.7 to 1.5 Ga Mesoproterozoic anorogenic magmatism is locally significant (Delgado, et al., 2003). There is a gap in the geological record of deposition and tectonic activity through much of the Mesoproterozoic, from 1.5 and 1.0 Ga (e.g., Neves, et al., 2021).
A few meta-sedimentary sequences in the Transverse and Southern sub-provinces have early Neoproterozoic Tonian, 1.0 to 0.92 Ga ages, particularly the meta-plutonic, volcanic and sedimentary rocks of the broad NE-SW trending Cariris Velhos (CV) Belt which was accompanied by the intrusion of mafic dykes and A-type granites between 1.0 and 0.85 Ga. This belt/domain, which represents an extensional regime, cuts obliquely across the core of the Transverse Sub-province, truncated by the east-west trending Patos-Campina Grande and Pernambuco shear zones to the north and south respectively. Sparse occurrences of that same belt are found offset across the Pernambuco Shear Zone in the Southern Sub-province (Brito Neves et al., 1995, Van Schmus et al., 1995, Kozuch 2003, Carvalho 2005, Santos et al., 2010, Oliveira et al., 2010, Caxito , 2014, 2020). However, most of the sedimentary basins of the province were formed in the mid to late Neoproterozoic, between 800 and 700 Ma, with sedimentation ending just before or at the onset of the Brasiliano Orogeny (Neves, et al., 2021). The presence of ophiolitic (Caxito et al., 2014, Lages et al., 2017) and eclogites/HP-UHP rocks (e.g., Santos et al., 2009, 2015, Amaral et al., 2015, Ganade de Araújo et al., 2014, Lages and Dantas 2016) within the Neoproterozoic meta-volcanosedimentary belts of the Borborema Province, along with detailed supporting geophysical data, suggest the amalgamation of younger lithospheric blocks of distinct separate composition, structure and age (e.g., Padilha et al., 2016, Santos et al., 2014, Lima et al., 2015, Oliveira and Medeiros 2018) are consistent with an evolution to subduction plate tectonic processes during the remainder of the Neoproterozoic (e.g., Caxito et al., 2016, Lages and Dantas 2016, Padilha et al., 2016) as detailed below:
• ~900 to 650 Ma - continuation of the early Tonian extension marked by ~900 Ma mafic-ultramafic intrusions (Brejo Seco; Salgado et al., 2016), ~882 Ma continental rift-like mafic volcanism (Caxito et al., 2016) and ~869 Ma A-type granitoids, now orthogneisses (Neves et al., 2015). This extensional regime is interpreted to reflect continental rifting and separation of the Transverse and Southern sub-provinces from the São Francisco-Congo palaeo-continent during the Tonian (Caxito et al., 2020). The rifting is interpreted to have culminated in spreading, accompanied by the emplacement of intervening oceanic crust from ~820 to 650 Ma, separating passive margin sequences deposited on the edges of the two receding continental blocks. Within the interior of the Borborema Province, further crosscutting rift/passive margin belts were developed.
• From ~650 to 590 Ma - the chronology of tectonic and magmatic events is similar across all of the sub-provinces of the Borborema Province from ~650 Ma, interpreted to reflect the widespread onset of subduction and continental arc development that persisted until ~620 Ma. The latter was particularly important along the southern margin of the province, as described in the Rio Preto, Riacho do Pontal and Sergipano Belt sections below. The ophiolite-bearing passive margin sequences of the southern edge of the province were thrust north over the basement and then covered by widespread syn-orogenic, greywacke-rich flysch units with intermediate to felsic volcanic and volcaniclastic intercalations (Caxito et al., 2016). The development of flysch-like basins characterises all of the supracrustal fold belts in all three sub-provinces, with very similar detrital zircon contents that are younger than ~650 Ma (U-Pb ages; e.g., Caxito et al., 2016; Brito Neves and Campos Neto 2016; Lima et al., 2018; Basto et al., 2019). This age is comparable to the 650 to 630 Ma Ediacaran Stage I, pre-collisional calc-alkaline plutons, e.g., the Conceição, Tamboril-Santa Quitéria, Major Isidoro, Betânia, and similar plutons in the Sergipano Belt (Fetter et al., 2003, Santos et al., 2008, Van Schmus et al., 2011, Oliveira et al., 2015, Brito Neves et al., 2016, Santos et al., 2019). The main collision stage of the Brasiliano Orogeny from 620 to 590 Ma led to the meta-volcanosedimentary basins being inverted, deformed and metamorphosed, with crustal anatexis generating Stage II syn-collisional plutons throughout the province. These were followed by interpreted post-collisional intrusions such as the ~588 Ma Glória Norte shoshonitic stock. Neoproterozoic belts within the Northern and Transverse sub-provinces, e.g., the Piancó-Alto Brígida Domain, may represent an ocean that opened and closed accompanied by subduction and arc magmatism. Alternatively it may be the product of rifting, followed by inversion and strong intracontinental imbrication and crustal thickening related to the compression experienced across the province. This would have produced anatectic magmatism during the collisional event on the province margin. Eclogite facies metamorphism in the Northern and Transverse Sub-province related to this event is dated at ~625 to 615 Ma (Ganade de Araújo et al., 2014; Santos et al., 2015; Lages and Dantas 2016).
• From ~590 to 510 Ma, during the final stages of the Brasiliano Orogeny, an extensive network of shear zones was developed that crosscut the Borborema Province and characterises the structural framework of NE Brazil. These shear zones are spatially and temporally linked to several post-collisional granite plutons (Stages III to V magmatism) throughout the province (e.g., Hollanda et al., 2010; Viegas et al., 2014). Ar-Ar plateau cooling ages show that extension associated with dextral shearing in the younger shear zones may have persisted until ~510 Ma (Hollanda et al., 2010). Ordovician and younger reactivation of the main lineaments is indicated by ~460 Ma felsic dykes crosscut by faults parallel to the main trend of the Transbrasiliano Shear Zone (Amaral et al., 2017).
Neves (2021) observes that the occurrence of Eo- to Palaeoarchaean rocks, the oldest in South America, and the temporal coincidence of Rhyacian orogenic events and in both the São Francisco Craton and Borborema Province is consistent with both being part of a single continent formed by the accretion of Archaean to early Palaeoproterozoic blocks and of juvenile arc crust during the Rhyacian Transamazonian Orogeny. In addition, the coincidence of several intraplate tectonomagmatic events from the late-Palaeoproterozoic to the Neoproterozoic indicates that they remained united until at least the Cryogenian in the mid-Neoproterozoic. In this context, the Borborema Province can be interpreted as a cluster of fragments of the São Francisco Craton reworked and re-accreted during the Brasiliano-Pan African Orogeny at ~640 to 550 Ma.
The main domains along the southern margin of the Southern Sub-province of the Borborema Province, namely the Rio Preto, Riacho do Pontal and Sergipano Belt are described separately below.

Borborema Province References
Caxito, F.A., Santos, Santos L.C.M.L., Ganade, C.E., Bendaoud, A., Fettous, E.-H. and Bouyo, M.H., 2020 - Toward an integrated model of geological evolution for NE Brazil-NW Africa: The Borborema Province and its connections to the Trans-Saharan (Benino-Nigerian and Tuareg shields) and Central African orogens; Brazilian Journal of Geology, v.50, 38p. doi:10.1590/2317-4889202020190122.
Delgado, I.M., Dalton de Souza, J., Silva, L.C., Silveira Filho, N.C., Santos, R.A. Pedreira, A.J., Guimarães, J.T., Angelim, L.A.A., Vasconcelos, A. M., Gomes, I.P., Lacerda Filho, J.V., Valente, C.R., Perrotta, M. M. and Heineck, C.A., 2003 - Geotectonics of the Atlantic Shield; in Bizzi, L.A., Schobbenhaus, C., Vidotti, R.M. and Gonçalves J.H., (eds.), Geologia, Tectônica e Recursos Minerais do Brasil, CPRM, Serviço Geológico do Brasil Brasília, pp. 227-334.
Neves, S.P., Teixeira, C.M.L. and Bruguier, O., 2021 - 870-850 Ma-old magmatic event in eastern Borborema Province, NE Brazil: Another Tonian failed attempt to break up the São Francisco Paleoplate?; Journal of South American Earth Sciences, v.105, doi.org/10.1016/j.jsames.2020.102917.
Neves, S.P., Tommasi, A., Vauchez, A. and Carrino, T.A., 2021 - The Borborema Strike-Slip Shear Zone System (NE Brazil): Large-Scale Intracontinental Strain Localization in a Heterogeneous Plate; GeoScienceWorld, Lithosphere, Volume 2021, 26p. doi.org/10.2113/2021/6407232.
Neves, S.P., 2003 - Proterozoic history of the Borborema province (NE Brazil): Correlations with neighboring cratons and Pan-African belts and implications for the evolution of western Gondwana; Tectonics, v.22, pp. 5-1 to 5-14. doi:10.1029/2001TC001352.
Neves, S.P., 2021 - Comparative geological evolution of the Borborema Province and São Francisco Craton (eastern Brazil): Decratonization and crustal reworking during West Gondwana assembly and implications for paleogeographic reconstructions; Precambrian Research, v.355, doi:10.1016/j.precamres.2021.106119

RIO PRETO BELT

This belt is developed along the northwestern margin of the São Francisco Craton. Its preserved width is confined to the north by the Parnaíba basement block where the two cratonic blocks are at their closest approach. It was deposited between 850 and 600 Ma in the Brasiliano Sea on a basement of Palaeoproterozoic quartz-feldspar orthogneisses, quartzite and garnet-muscovite schists of the ~1.9 Ga Formosa Formation and the 2.1 Ga (Rb-Sr whole rock isochron) Cristalandia do Piauí Complex biotite-gneiss and amphibolite. The Rio Preto sequence comprises the km-thick Canabravinha Formation which is composed of lithic quartzite, phyllite, sandy-pelitic meta-rhythmite, meta-diamictite, and locally meta-marl, deposited on a submarine slope-apron dominated by gravitational mud flows and turbidity currents in an east-west, fault bounded intracontinental rift. It has been deformed during the 600 to 540 Ma Brasiliano Orogeny to low to medium grade pelitic schists and quartzites, with rare 971 Ma alkaline granite clasts and 850 Ma youngest detrital zircons (Caxito et al., 2012). The contact zone with the basement metamorphics is marked by deformation in the metapelites producing a steep south dipping foliation that becomes increasingly weak towards the north, forming an asymmetrical 'positive flower structure' (Barbosa et al., 2012). The Neoproterozoic Canabravinha Formation is interleaved with older basement, occurring as a complex, asymmetrical and double-verging thrust wedge, whose southern branch propagated for >100 km into the craton interior in form of a thin-skinned deformation front, bounded to both the north and south by older basement (Caxito et al., 2017). It is also overthrust in the south onto the Neoproterozoic Bambuí Group carbonates that are inferred to be stratigraphic equivalents. To the NW of the craton, it passes below the thick Phanerozoic Parnaíba Basin cover sequence where it is assumed to be truncated by the Transbrasiliano Lineament which separates it from the concealed Parnaíba Block.

Rio Preto Belt References
Caxito, F.A., Uhlein, A., Dantas, E., Stevenson, R., Egydio-Silva, M. and Salgado, S.S., 2017 - The Rio Preto and Riacho do Pontal Belts; in Heilbron, M., Cordani, U.G. and Alkmim, F.F., (Eds.), São Francisco Craton, Eastern Brazil, Springer Regional Reviews, pp. 221-239. doi 10.1007/978-3-319-01715-0_12.
Caxito, F.A., Uhlein, A., Sanglard, J.C.D., Gonçalves Dias, T., and Mendes M.C.O., 2012 - Depositional systems and stratigraphic review proposal of the Rio Preto Fold Belt, northwestern Bahia/southern Piauí; Revista Brasileira de Geociências, v.42, pp. 523-538.

RIACHO DO PONTAL FOLD BELT

The Riacho do Pontal Fold Belt borders and onlaps the northern margin of the São Francisco Craton between the Rio Preto and Sergipano belts that are to the west and east respectively. It has been divided into internal, central and external zones, with the latter having been thrust over the main craton margin. Basement to the external thrust sheets is composed of Palaeoarchaean and younger TTG-orthogneiss with tonalitic, granodioritic and locally significant leucogranite bands of the Gavião (or Sobradinho) Block, and Palaeoproterozoic supracrustal quartzite and calc-silicatic rocks, as well as granitic plutons and locally important amphibolite dykes (Santos and Silva Filho 1990; Figueirôa and Silva Filho 1990). Palaeoproterozoic (2.2 to 2.0 Ga) orogenic reworking of these assemblages is significant (e.g., Santos and Silva Filho 1990).
The Internal zone, extends from just north of the craton margin, through the Southern Sub-province of the Borborema Province to the Pernambuco Shear Zone. In the north, the oldest suites include the 1000 to 960 Ma Afeição Augen Gneiss. These rocks are metamorphosed to upper greenschist to lower amphibolite facies and intensively deformed. The younger ~900 to 820 Ma Morro Branco Complex quartz-mica schist, phyllite, meta-chert, quartzite, metabasalts, rhyodacitic, dacitic and rhyolitic metavolcanics, basaltic (dated at 882.8 ±4.4 Ma; U-Pb zircon; Caxito et al., 2016) to felsic metatuffs, as well as subordinate graphite-schists. Volcanosedimentary sequences include the: Paulistana Complex composed of an ~900 to 820 Ma suite of garnet-mica schists and muscovite quartzites with intercalated metabasalts and amphibolites after gabbros and ultramafic lenses. The Santa Filomena Complex, of similar age, comprises coarse muscovite, biotite, garnet, kyanite, staurolite, cordierite and sillimanite schists, with local calcitic marble intercalations. These volcano-sedimentary sequences are intruded by large volumes of igneous rocks, including the 900 to 820 Ma Brejo Seco and São Francisco de Assis mafic-ultramafic complexes and younger 650 to 555 Ma granitoids as discussed below. The Brejo Seco mafic-ultramafc layered intrusion is tectonically interleaved within the Morro Branco volcanosedimentary sequence and is interpreted to have been emplaced in a continental rift setting at ~900 Ma ago (Salgado et al., 2016; Caxito et al., 2017).
The Central zone, close to the Borborema-São Francisco Craton margin is characterised by a 100 km long, east-west trending synformal structure which is dominated by the Monte Orebe Complex, mainly composed of mafic metavolcanics (actinolite schists, amphibolites and meta-tuffs), interleaved within deep-sea pelagic metasedimentary rocks, mainly metachert (locally iron-rich) and garnet-mica schist, with local metagreywacke and quartz-schist. Preliminary lithochemistry and trace elements data suggests a tholeiitic, MORB-type affiliation for the mafic igneous protoliths of the Monte Orebe Complex, which may therefore represent oceanic crust marking a suture zone (Caxito et al., 2017).
The External zone is mostly found structurally overlying the margin of the craton. It is predominantly occupied by the Casa Nova Group, which is subdivided into the Barra Bonita and Mandacaru formations. The Barra Bonita Formation, is mainly composed of a shallow marine platformal sequence of fine-grained mica schists that have garnet porphyroblasts, phyllites, interbedded muscovite-quartzite and marble lenses that can be up to 200 m thick. This formation has been correlated with the Una Group of the Chapada Diamantina Domain of the São Francisco Craton. The Mandacaru Formation is interpreted to represent a deep-sea turbiditic, syn-orogenic sequence, mainly composed of garnet mica schists with centimetric intercalations of meta-greywacke containing detrital feldspar, quartz, muscovite, garnet and chlorite (Caxito et al., 2017). The external zone comprises a south-verging thin-skinned nappe system detached along the basement-cover contact. Ages of syn- to late-collisional granitic intrusions suggest that the main deformation phase in the Riacho do Pontal Belt occurred between 667 and 555 Ma (Barbosa et al., 2021). The External Zone of the Riacho do Pontal Belt is broadly structurally and stratigraphically equivalent to the Rio Preto Fold Belt to the west.
Large numbers of Neoproterozoic granitoid plutons divided into i). syn-collisional, tabular, mesocratic, fine to medium-grained two-mica orthogneisses with U-Pb zircon crystallisation ages between 620 and 575 Ma (Caxito 2013; Brito Neves et al., 2015; Caxito et al., 2016); ii). syn- to late collisional, grey to pinkish syenites, quartz-syenites and associated granites, with pegmatite and syeno-granite dykes, in the Sobradinho Dam area, that have yielded an Rb-Sr whole-rock isochron age of 555 ±10 Ma (Jardim de Sá et al., 1996); iii). late- to post-collisional, oval shaped plutons in the NW, composed of grey to pink medium to coarse-grained syenite and K feldspar granite, locally overprinted by late-stage shear zones. Some of the latter have an alkaline affinity, with peralkaline/shoshonitic/potassic phases (Gava et al., 1984). While the bulk of these granitoids are concentrated in the Internal Zone, they are also spread across the belt.
Between ~1000 and 820 Ma, the Riacho do Pontal Fold Belt is considered to represent an early extensional phase characterised by the emplacement of the Brejo Seco and São Francisco de Assis mafic-ultramafic complexes and the rift related Paulistana Complex volcano-sedimentary sequences, possibly initiated by a mantle plume. As extension and rifting progressed further, bimodal volcanism and sedimentary deposition continued, with the passive margin Barra Bonita sequence extending over the craton on the rift margin until ~630 Ma. From ~630 Ma, the dynamics reversed to compression and subduction below the Central Zone, whilst a magmatic arc developed in the Internal Zone to the north. During the same period, the thick, deeper marine Mandacaru Formation flysch was deposited, centred on the Central Zone. Continental collision is interpreted to have taken place at ~620 Ma and continued until ~575 Ma with a south-verging thin-skinned nappe system thrust onto the northern São Francisco Craton. Finally, a phase of lateral escape from ~575 to 530 Ma followed continental collision, accompanied by the development of crustal scale structures, such as the Pernambuco Shear Zone, as well as granite and syenite intrusions (Caxito et al., 2017).

Riacho do Pontal Belt References
Barbosa, J.S.F., et al., 2021 - Explanatory Note of the Tectonic-Geochronological Map of the State of Bahia: metallogenetic implications, Bahia Mineral Research Company - CBPM. VIII. Geological Survey of Brazil - CPRM. Special publications series, v.24, 52p.
Caxito, F.A., Uhlein, A., Dantas, E., Stevenson, R., Egydio-Silva, M. and Salgado, S.S., 2017 - The Rio Preto and Riacho do Pontal Belts; in Heilbron, M., Cordani, U.G. and Alkmim, F.F., (Eds.), São Francisco Craton, Eastern Brazil, Springer Regional Reviews, pp. 221-239. doi 10.1007/978-3-319-01715-0_12.

SERGIPANO FOLD BELT

The Neoproterozoic Sergipano Belt is the southern half of the Southern Sub-province of the Borborema Province, bounded to the north by the Marancó Shear Zone (MSZ) which separates it from the Pernambuco-Alagoas Terrane (PAT) that forms the northern half of the sub-province. To the SW, it overlies the eastern São Francisco Craton. From north to south, the Sergipano Belt is divided into six lithostratigraphic domains, the first three of which straddle the Marancó Shear Zone and incorporate plutonic, volcanic and sedimentary rocks, namely the Canindé, Poço Redondo and Marancó groups. The southern three are sedimentary suites, the Macururé, Vaza Barris and Estância groups. These domains reflect an evolution that involved:
i). The basement Pernambuco-Alagoas Terrain (PAT) to the north underwent a complex polycyclic evolution. It is composed of gneissic- migmatitic-granitic rocks of Archaean and Paleoproterozoic (Orosirian) age, which enclose bands of supracrustal rocks that record orogenic events in the Mesoproterozoic, Neoproterozoic (Tonian), the placement of granitoids at ~1.0 Ga, and a collision event during the Brasiliano Cycle at 0.75 to 0.57 Ga (Barbosa et al., 2021).
ii). an early ~980 to 960 Ma Neoproterozoic magmatic suite exposed as the Poço Redondo granodioritic to tonalitic orthogneiss, developed on the southern margin of the Palaeoproterozoic to Neoproterozoic Pernambuco-Alagoas Block in the north. Whilst Oliveira et al. (2017) regard these orthogneisses to be due to north dipping subduction of the oceanic crust separating the Pernambuco-Alagoas Terrain and São Francisco Craton below the former, the similar aged magmatism and setting in the adjacent Riacho do Pontal Fold Belt is interpreted to be the result of an extensional regime (e.g., Caxito et al., 2017).
iii). Subsequent extension of the southern continental Pernambuco-Alagoas Block gave rise to:
• Deposition after ~950 Ma of the Marancó Group that are now greenschist- to amphibolite facies, pelitic to psammitic metasedimentary rocks and rhythmites overlying and derived from the Poço Redondo intrusions, interleaved with calc-alkaline andesite to dacite beds, with associated basalt, andesite, gabbro, peridotite and serpentinite (Oliveira et al. (2017). Broadly coeval A-type crustal granite was intruded into basement and sedimentary rocks deposited on the attenuated and rifted southern margin of the combined Poço Redondo/Marancó block (Oliveira et al., 2017);
• Continued extension on the southern section of the Pernambuco-Alagoas Block resulted in the opening of a new rift basin between the main block and the Poço Redondo/Marancó domain on its southern margin. This new basin was the centre of deposition of the Canindé rift sequence from ~750 Ma. This rifting persisted until ~625 Ma, leading to emplacement of a bimodal association of ~715 Ma A-type granites and continental mafic volcanic rocks, a ~700 Ma continental layered gabbroic complex, a 688 Ma magma-mingled gabbro/quartz-monzodiorite, and 684 and 641 Ma rapakivi granites. Interleaved, deformed pillowed basalts and marble lenses are interpreted to be ocean floor relicts from the Canindé rift basin (Oliveira et al., 2017);
• Development of a passive margin on the southern boundary of the Pernambuco-Alagoas block, upon which sedimentary rocks were deposited soon after 900 Ma as the Macururé Group which yielded detrital zircons with a mimimum age of 800 to 856 Ma (Oliveira et al., 2017);
• A sedimentary shelf/passive margin had also developed on the opposite, or southwestern side of the basin, lapping onto the São Francisco Craton.
iv). Inversion and then closure of the Canindé rift basin began at ~630 Ma, resulted in the progressive intrusion of arc-type granites into the Macururé (628 to 625 Ma), Poço Redondo/Marancó (~625 Ma) and Canindé (~621 Ma) domains (Oliveira et al., 2017).
v). Convergence between the newly re-amalgamated Pernambuco-Alagoas (PAT) block and the São Francisco Craton resulted in deformation on the passive margins and the emplacement of granite between 590 and 570 Ma, predominantly into the Macururé Group. Associated uplift led to exhumation of the Pernambuco-Alagoas Block and the Canindé, Poço Redondo/Marancó and Macururé domains in the north, and deposition of the clastic sedimentary rocks of the Estância and Vaza Barris domains in the south, interpreted to represent a foreland basin. Minimum aged detrital zircons in these two groups are 995 to 570 Ma and 2000 to 553 Ma respectively. This convergence culminated in the final thrusting of the continental margin sedimentary rocks of the Estância, Vaza Barrisonto and Macururé domains over the São Francisco Craton. The Pernambuco-Alagoas Block is now in contact with the São Francisco Craton on the western end of the Sergipano Belt, while on the Atlantic coast to the east, the two blocks are separated by ~180 km of the Sergipano lithostratigraphic domains, with scattered exposures of basement in windows through the cover (Barbosa et al., 2021; Oliveira et al., 2017).

Riacho do Pontal Belt References
Oliveira, E.P., Windley, B.F., McNaughton, N.IJ., Bueno, J.F., Nascimento, R.S., Carvalho, M.J. and Araújo, M.N.C., 2017 - The Sergipano Belt; in Heilbron, M., Cordani, U.G. and Alkmim, F.F., (Eds.), São Francisco Craton, Eastern Brazil, Springer Regional Reviews Springer International Publishing Switzerland, pp. 241-254. doi 10.1007/978-3-319-01715-0_13.
Barbosa, J.S.F., et al., 2021 - Explanatory Note of the Tectonic-Geochronological Map of the State of Bahia: metallogenetic implications, Bahia Mineral Research Company - CBPM. VIII. Geological Survey of Brazil - CPRM. Special publications series, 24.

TOCANTINS PROVINCE

The Tocantins Province of central Brazil is a large Neoproterozoic, Brasiliano-Pan African Orogen framed by five major cratonic blocks, the exposed Amazonian and São Francisco cratons to the NW and SE respectively, the concealed Parnaíba Block to the NE, the Paranápanema Block to the south, and the Rio Apa Block to the SW. The latter is either a satellite, or extension of, the larger Rio de la Plata Craton. To the northeast, the Phanerozoic Parnaíba cratonic basin, which separates it from the complex Borborema Province, almost completely conceals the Parnaíba Block. To the south and SW the Tocantins Province is also overlain by the similar cratonic Paraná Basin which completely overlies and masks the Paranápanema Block which is only defined from geophysical data.
The Tocantins Province is made up of four main structural elements, i). the north-south Araguaia Fold Belt to the north, that has been thrust to the west over the Amazonia Craton, and is unconformably overlain to the east by the Parnaíba Basin; ii). the NNW-SSE elongated Brasilia Fold Belt to the south that has been thrust to the east over the São Francisco Craton, and is unconformably overlain by the Paraná Basin to the south; iii). the arcuate ENE-WSW to near north-south Paraguaia Fold Belt to the west, that has been thrust to the north over the Amazonia Craton and to the west over the Rio de la Plata cratonic collage, and is, in turn, overlain by Phanerozoic Paraná Basin and Cenozoic Pantanal Basin; iv). the composite Archaean to Mesoproterozoic Goiás Massif and Neoproterozoic Goiás Magmatic Arc that occupies the triple point where the three aforementioned fold Belts coalesce. The main basement elements of the Goiás Massif, from SW to NE are the Crixás-Goiás Terrane, Campinorte Terrane, Cavalcante-Arraias Terrane and the Almas-Conceição do Tocantins Terrane.
Each of these elements and their bounding cratons and basins are described below in more detail. See the first figure in the Carajás IOCG Province record for the continental scale setting, and Fig. 1 below for the distribution of the structural elements listed above.

GOIÁS MASSIF

The Goiás Massif is a collage of Archaean to Palaeoproterozoic terranes that are exposed in the core of the Tocantins Province, at the triple point where the Brasilia, Paraguaia and Araguaia fold belts intersect. It represents uplifted, exposed basement and extends over a NE-SW elongated length of ~700 km, with widths varying from 75 to 200 km. It is composed of four main Terranes, from SW to NE as follows:

Crixás-Goiás Terrane
The Crixás-Goiás Terrane is composed of ~70% batholith-like Mesoarchean to Early Neoarchean TTG complexes, with the remaining 30% as five greenstone belts that occur as synformal keels. The terrane has been subdivided on the basis of TTG ages and composition into a Northern and a Southern Block, separated near the centre of the Terrane by the NW-SE Rio Tesouras Lineament (Fig. 2). The TTG complexes are intensely deformed orthogneiss of variable composition and age, but also including minor granite, charnockite, monzogranite and adakite-like rocks. They were formed during a number of discrete magmatic episodes from as early as 3.10 Ga (Beghelli, et al., 2012). The most preserved were emplaced at 2.96 to 2.84, 2.845 to 2.785 and 2.79 to 2.70 Ga (Bogossian et al., 2021, and references cited therein). The most widespread in both blocks are the 2.96 to 2.84 and 2.845 to 2.785 Ga episodes. The Northern Block comprises two major magmatic stages i). polydeformed batholith-like, ~2.84 to 2.78 Ga (U-Pb zircon, SHRIMP) tonalite, granodiorite and granite orthogneiss; and ii). crust-derived, dyke-like, ~2.79 to 2.70 Ga (U-Pb zircon SHRIMP) granodiorite to granite gneiss. The latter are dominant in this block and appears to be the last magmatic event in the Terrane. The Southern Block comprises the Uvá and Caiçara TTG gneisses, separated by a composite greenstone belt. The Crixás-Goiás Terrane appears to have been stabilised by 2.70 Ga, followed by the onset of rifting and crustal extension between 2.50 and 2.30 Ga (Corrêa da Costa, 2003), and then inversion and closure of accretionary orogens between 2.30 and 2.05 Ga.
The southern two greenstone belts, the Faina and Goiás (or Serra de Santa Rita) belts are contiguous, but are offset by the NE-trending, dextral Faina fault. Each is of the order of ~60 km long by 5 km wide, and trends at ~300°. On the basis of their geometry and lithostratigraphy, both are interpreted as synformal keels. The northern three however, are interpreted to be fold-thrust belts. They trend north-south and, from the west to east, are the Crixás, Guarinos and Pilar de Goiás greenstone belts. Each is of the order of ~40 km long by 6 km wide. Overall, all of the greenstone belts contain a similar sequence comprising a lower 400 to 900 m thick komatiite with preserved spinifex and/or cumulatic textures; followed by 300 to 500 m of tholeiitic basalt flows, characterised by pillow and variolitic structures with local dolerite and gabbro dykes/sills. Minor thin layers of BIF and gondite, and/or chert lenses are intercalated with the volcanic rocks. The transition from the volcanic to the overlying sedimentary rocks is typically marked by a 'tectonic unconformity'. Unlike the common lower mafic-ultramafic sequences, the overlying sedimentary units indicate diverse depositional regimes between the five greenstone belts. In the Crixás Belt, the sedimentary sequence commences with carbonaceous schists typical of a euxinic environment, with oolitic to stromatolitic dolomitic marbles that are unconformably overlain by pelites and greywackes. At Guarinos, lower chlorite-rich pelites containing clasts of basalt are laterally interlayered with basalts that are overlain by chemical sedimentary rocks (BIF, chert), conglomerate lenses and pelites. The Pilar de Goiás greenstone belt, calc-silicate rocks, sandstone and dolomite are followed by greywackes. Both the Faina and Goiás greenstone belts in the south also contain felsic rocks in the volcanic suite, with the overlying sedimentary suite comprising siliciclastic, pelitic and chemical rocks. The Goiás greenstone belt is characterised by lower carbonaceous pelites followed by chert, BIF and dolomite, unconformably overlain by turbidites. The Faina greenstone belt has two sequences consisting of lower conglomerate, quartzite and pelite overlain by chemically precipitated rocks (Bogossian et al., 2021, and references cited therein).
The volcanic sequences in the Faina and Goiás (or Serra de Santa Rita) greenstone belts to the SW, have a maximum depositional age of between ~2.96 and 2.92 Ga (zircon U-Pb LA-ICP-MS), whilst that at the Crixás Belt is indicated as 3.00 Ga (Sm-Nd whole-rock isochron). In contrast, the lower volcanic rocks of the easternmost pair, the Guarinos and Pilar de Goiás greenstone beltsare dated at 2.18 and 2.165 Ga respectively (Bogossian et al., 2021, and references cited therein) and are therefore represent a separate event. Meta-basalts of the Guarinos Belt interfinger laterally with ~300 m of metarhythmites. Both are overlain by ~80 m of banded iron formation (BIF; Aimbé Formation) with minor lenses of meta-conglomerate and meta-shale. The BIF grades up into the Cabaçal Formation which commences with ~300 m of carbonaceous schist and then into >300 m of meta-rhythmites. In the Pilar de Goiás Greenstone Belt, the metabasalts are transitional to a lower 10 m thick manganese-rich layer, then a 50 m thick meta-chert, and finally a 180 m thickness of calc-silicate rocks. This section is overthrust by ~400 m of carbonaceous schist, meta-pilite, meta-chert lenses, BIF and manganese horizons of the Serra do Moinho Formation. Relict primary structures suggest the Crixás and Guarinos belts are overturned, but the Pilar de Goiás Belt is not (Jost et al., 2001).
The Archaean TTG complexes and volcanic rocks from the Goiás, Faina and Crixás belts are crosscut by a mafic dyke swarm dated between 2.50 and 2.30 Ga, constraining their upper age. However, those dykes do not cut the overlying sedimentary sequences of those same greenstone belts. This implies that the sedimentary units were deposited following or during regional crustal extension after 2.30 Ga. The cessation of sedimentation is indirectly indicated by carbon isotopes of upper dolomitic rocks from the northern greenstone belts and the lower sedimentary sequence from the southern pair, coupled with available geochronology, suggesting their deposition between 2.22 and 2.06 Ga (Bogossian et al., 2021, and references cited therein).
The rocks of the Crixás-Goiás Terrane have been subjected to at least three deformation events, as measured in the Crixás Açu gneiss of the Crixás Greenstone Belt, namely in the Archaean, Palaeoproterozoic and Neoproterozoic, at ~2711, 2011 and 590 Ma respectively (titanite U-Pb SHRIMP; Queiroz et al., 2000; 2001).
Bogossian et al. (2021) propose an Archaean Dn event that resulted in regional amphibolite facies metamorphism and deformation of all granite-gneiss TTG complexes and the lower volcanic sequences of the Crixás, Faina and Goiás greenstone belts. It produced a moderately NE- to NW-dipping metamorphic foliation (Sn) and local north-vergent open folds, with zones of thrust faulting and associated tight to isoclinal folding. Sn is expressed by the alignment of talc-serpentine-chlorite ±titanite in the volcanic rocks and quartz-hornblende-biotite-epidote-titanite in TTG granite-gneisses. Contacts between granite-gneiss TTG complexes and volcanic rocks in the two southern greenstone belts are commonly marked by deformed xenoliths of the latter, taken to suggest the greenstone belts are allochthonous. In the Northern Block, the ~2.7 Ga metamorphic event is coeval with emplacement of younger orthogneisses, whilst in the Southern Block, metamorphism is dated at ~2.84 Ga. The minimum age of the Dn event is 2490 ±40 Ma, the age of crosscutting mafic dykes (Bogossian et al., 2021, and references cited therein). Other authors, e.g., Ferreira et al. (2021), Ulrich et al. (2021); Jost et al. (2010, 2019), do not apparently recognise Dn. All agree on a pre-deformational ultramafic and mafic magmatic event during the Archaean, overlain across a nonconformity by an early Rhyacian (NOTE: Rhyacian = 2.30 and 2.05 Ga in the Palaeoproterozoic) rifting stage restricted euxinic basin with clastic input from a Rhyacian arc. Jost et al. (2010, 2019) suggest a post-rift Rhyacian deformation and metamorphism similar to the Archaean Dn of Bogossian et al. (2021). Each of these authors recognise a different set of deformations, ranging from two (Ferreira et al., 2021), four (Jost et al., 2010, 2019), four (Ulrich et al., 2021 at Crixas, and Bogossian et al., 2021). Jost et al. (2010, 2019), Ferreira et al. (2021) and Ulrich et al. (2021) regard D3 and 4 to both be Neoproterozoic, whilst Bogossian et al. (2021) suggests only D4 is of the latter age. Also, the number of the deformations do not correlate between authors. Bearing in mind the significant variation in interpretation, that of Bogossian et al. (2021) is briefly summarised below to give an indication of the style and distribution of deformation in the terrane. Note also there are differences between the northern and southern blocks.
Bogossian et al. (2021) recognised a Rhyacian D1 deformation producing an early, gently west to north dipping S1 affecting the Rhyacian volcano-sedimentary rocks as well as the older lithologies. It is parallel to subparallel to S0 which has been transposed into S1, with NW-striking, axial planar tight to isoclinal folds and inversion of the greenstone belt stratigraphy. This was accompanied by regional greenschist to lower amphibolite facies quartz-chlorite-muscovite-biotite ±epidote metamorphic assemblages, oriented parallel to S1, and formed at temperatures that are roughly at the brittle-ductile transition. In the north, there are north-south striking and gently west dipping thrust faults. D2, which is also Rhyacian, saw a rotation in stress field with a gently south dipping S2 foliation, planar axial to tight recumbent F2 folds and gently south to north dipping, narrow, east-west striking thrust faults stacking the stratigraphy. This deformation coincided with the main gold mineralising event at Crixas; D3 is the third of the Rhyacian deformation events, producing an S3 that is gently east dipping in the north and moderatley north dipping in the south. In the north there are north-south F3 folds and lateral thrust ramps, while in the south, NW-striking shear zones and gently south-dipping thrust faults are evident. D1 to D3 events are limited by various post-deformational intrusions emplaced between ~2170 and 2061 Ma. D4, is interpreted to be a Neoproterozoic event that overprints, offsets and/or reactivates previous structures, but in particular leads to the overthrusting of Neoproterozoic sequences of the Mara Rosa magmatic arc southward and eastward onto the Crixás-Goiás Terrane. It is reflected by a schistosity in the hanging wall of the Rio de Bois Thrust which separates Crixás-Goiás Terrane and Mara Rosa magmatic arc and by a south to west plunging crenulation lineations associated with thin-skinned, east-vergent thrusting to reverse faulting and local north-south trending open folding (Araújo Filho et al., 2000). This event is attributed to the Brasiliano/Pan-African orogeny between 650 and 480 Ma (Alkmim et al., 1998). The age range is constrained by a 729 ±15 Ma leucogranite intrusion into the Guarinos greenstone belt (hydrothermal zircon, U-Pb LA-ICP-MS Rodrigues et al., 2011) to a minimum by the Serra Negra intrusion on the western border of the terrane of 527 ±5 Ma (zircon, U-Pb SHRIMP; Bogossian et al., 2021).

Crixás-Goiás Terrane References
Bogossian, J., Kemp, A.I.S., and Hagemann, S.G., 2021 - Linking Gold Systems to the Crust-Mantle Evolution of Archean Crust in Central Brazil, Minerals (MDPI), v.11, 35p. https://doi.org/10.3390/min11090944. Ulrich, S., Hageman, S., Marques, J.C., Figueiredo, F.L.A.R., Ramires, J.E.F., Frantz, J.C. and Petersen, K., 2021 - The Orogenic Crixas Gold Deposit, Goias, Brazil: A Review and New Constraints on the Structural Control of Ore Bodies; Minerals (MDPI), v.11, 27p. doi.org/10.3390/min11101050. Cordeiro, P.F. de O. and Oliveira, C.G., 2017 - The Goiás Massif: Implications for a pre-Columbia 2.2-2.0 Ga continent-wide amalgamation cycle in central Brazil; Precambrian Research, v.298, pp. 403-420.

Campinorte Terrane
Over much of its length, the Campinorte Terrane is bounded to the NW and SE respectively (i.e., above and below) by the major Rio dos Bois and Rio Maranhão thrusts, both of which are SE vergent. The lowest unit of the Campinorte Terrane, the Palaeoproterozoic Campinorte Sequence, is structurally juxtaposed against the 2785 ±5 Ma Hidrolina Complex TTG granite gneiss of the Crixás-Goiás Terrane to its SW, and has been temporally correlated with the Palaeoproterozoic sequence of the Guarinos and Pilar de Goiás Greenstone belts in the latter terrane (as described above). The Campinorte Sequence, which Cordeiro et al. (2014) described as part of the juvenile Paleoproterozoic Campinorte Arc, is composed of 2.19 to 2.07 Ga metavolcano-sedimentary rocks that are only exposed in structural and erosional windows through younger cover rocks. The sequence is dominated by quartz-muscovite schist with variable carbonaceous material, quartzite, chert and gondite lenses. Small elongated bodies of subordinate meta-tuffs and meta-lapilli tuffs occur within a range of metasedimentary rocks with rare felsic meta-volcanics. A felsic tuff of the latter has been dated at 2179 ±4 Ma (Giustina et al., 2009). At least two deformational events in the Palaeoproterozoic and Neoproterozoic have been recorded in these greenschist facies rocks, disrupting the original stratigraphy (Oliveira et al., 2006). Intensely weathered ultramafic talc-, amphibole- and chlorite-bearing schists within the sequence are interpreted to represent tectonic slices of ocean floor imbricated during basin inversion (Giustina et al., 2009). The up to 12 x 2 km, NNE elongated, calc-alkaline Pau de Mel Suite, composed of variably deformed, intrusive meta-tonalites, meta-granodiorites and meta-monzogranites occur within the Campinorte Sequence metasedimentary rocks. This suite has a juvenile character and is of Upper Rhyacian age, dated over the range from 2.17 to 2.07 Ga (Cordeiro et al., 2014). Paragranulite and mafic granulite are exposed in structural windows though the Mesoproterozoic cover, occurring as sillimanite-garnet-cordierite kinzigitic gneiss interpreted to be after metapelites and to belong to the Campinorte Sequence. The interpretation that the Campinorte Sequence and Pau de Mel Suite represent a late Rhyacian Campinorte Arc, is consistent with a contractional, subduction related orogenic amalgamation event that is evident across the Atlantic Shield, particularly within the São Francisco Craton and it margins. A metamorphic peak registered by granulite metamorphism in the Campinorte Arc occurred from 2.11 to 2.08 Ga (Cordeiro et al., 2014). Cordeiro and Oliveira (2017) interpret this event as marking the final stage of amalgamation of the Goiás Massif, followed by a regional rifting episode.
In the northern half of the terrane, the Campinorte Sequence is cut by a series of A-type Mesoproterozoic 'tin granites' known as the Serra da Mesa Suite (Pimentel and Botelho, 2001; Pimentel et al., 1999; Alvarenga et al., 2007). These have been dated at between 1658 and 1574 Ma (Dardenne, 2000; Pimentel et al., 1991) and occur as large intrusions to the west of the Rio Maranhão Thrust and smaller masses, up to 1 km wide, to the east of the same structure. These granites are interpreted to be the result of regional intracontinental magmatism, related to regional extension within the Goiás Massif.
This same extensional event was accompanied by deposition of the Serra da Mesa Group metasedimentary succession which almost entirely covers the Campinorte Sequence following a depositional break. This group is variously recorded as being Meso-, Meso- to Neo- and Neoproterozoic, although sources quoted by Slezak (2012) suggest it spans the interval from 1600 to 1470 Ma in the Mesoproterozoic and is composed of quartzites, micaceous schists and marbles (Dardenne, 2000; Fuck and Marini, 1981; Marini et al., 1984).
A string of three major layered mafic-ultramafic complexes, from SW to NE, the Barro Alto (BA), Niquelândia (N) and Cana Brava (CB) intrusions, are aligned over a 350 km, NE to NNE trend along the southeastern margin of the Campinorte Terrane. They lie immediately NW of the SE vergent Rio Maranhão thrust. Locally, the footwall of these complexes and the thrust are separated by heavily deformed Campinorte Sequence rocks, occurring as coarse granodioritic to tonalitic mylonite to ultramylonite that is zoned towards distal sillimanite-garnet-biotite gneiss, indicative of upper amphibolite facies metamorphism (Fuck et al., 1981). These layered complexes vary from 10 to 25 km in maximum width at surface, with strike lengths varying from 45 to 170 km at the Niquelândia and Barro Alto complexes respectively. The geological history of these complexes has been controversial, with some authors (e.g., Cordeiro and Oliveira, 2017) suggesting all three are composite intrusions, each with lower and upper segments formed during two distinct igneous events at 1.30 and at 0.79 Ga respectively, which were later juxtaposed during tectonic exhumation at 0.65 Ga. Other authors present data that indicates all three were formed during the same event, constrained between 800 and 770 Ma (zircon U-Pb SHRIMP-II; Giovanardi et al., 2017). Giovanardi et al. (2017) also suggest these complexes may represent a tectonically dismembered original single layered intrusion.
Whilst the footwall of the Barro Alto, Niquelândia and Cana Brava complexes is largely defined by the Rio Maranhão thrust plane, they exhibit intrusive hanging wall contacts with the metamorphosed Palmeirópolis, Indaianópolis and Juscelândia volcano-sedimentary successions respectively. The most extensive of these is the Palmeirópolis Sequence, which forms the hanging wall of the Cana Brava Complex. It is exposed over a strike length of ~80 km and width of up to 35 km. These sequences are mainly composed of metasedimentary successions that include meta-chert, meta-pelite and calc-silicate rocks with interbedded amphibolite, gneiss, and intrusive and sub-volcanic granite (Araújo, 1996; Araújo et al., 1995; Brod and Jost, 1991; Ferreira Filho et al., 2010; Moraes and Fuck, 1994, 1999; Moraes et al., 2003, 2006). The metavolcanic rocks of these sequences have E-MORB and N-MORB geochemical affinities, and are interpreted to possibly indicate a transitional setting from the continental rift in which the Serra da Mesa sedimentary succession was deposited, progressing to an oceanic basin setting. They have been dated as Mesoproterozoic, with ages between 1.26 and 1.30 Ga (Ferreira Filho et al., 2010; Moraes et al., 2006; Pimentel et al., 2000). They exhibit amphibolite-facies metamorphism near the contacts with the intrusive complexes, locally recrystallised to granulite-facies, grading to greenschist facies further to the west (Araújo, 1996; Ferreira Filho et al., 2010; Moraes et al., 2003, 2006). The nature of the contact between the Serra da Mesa Group and the metamorphosed Palmeirópolis, Indaianópolis and Juscelândia volcano-sedimentary successions has not been encountered during research for this summary.
Giovanardi et al. (2017) suggest the Barro Alto, Niquelândia and Cana Brava intrusive complexes have a common stratigraphy, although not all units of that succession are present in all three complexes. The succession comprises a Lower and an Upper Sequence. The Lower Sequence is common to all complexes, whilst the Upper Sequence is only exposed at Niquelândia and in the northern north-south section of Barro Alto. At Cana Brava and the southern east-west section of Barro Alto, the Lower Sequence ends with the upper Middle Zone, which, in both complexes has an intrusive contact with the overlying metavolcanic-metasedimentary sequence. The stratigraphic succession is as follows, from the base:
Lower Sequence
• Lower Mafic Zone - mainly composed of gabbros, recrystallised to micro and mylonitic textures and/or epidote-bearing amphibolites, interpreted to reflect the tectonic emplacement of the complexes over the Rio Maranhão Thrust Zone and concomitant pervasive percolation of fluids (Biondi, 2014; Correia and Girardi, 1998; Correia et al., 1999; Girardi et al., 1986).
• Ultramafic Zone, occurring as serpentinite, interlayered with amphibolite after gabbro and pyroxenite, which are present as subordinate relics. Primary cumulus textures are commonly preserved. Recrystallisation diminishes upward to where pyroxenites (websterites and lesser orthopyroxenites) predominate. The transition to the overlying unit is characterised by increasing gabbro and decreasing pyroxenite layers.
• Mafic Zone, composed of gabbros, gabbro-norites and norites. The abundance of amphibole increases discontinuously upward through the sequence, reaching its maximum at the top of this unit, where an increase in biotite is also evident. This zone contains discontinuous diorite, which sometimes incorporates garnet, as well as meta-volcanic and sedimentary xenoliths which include decametre long quartzite lenses. The xenoliths have variable dimensions and their composition varies, including amphibolite, garnetiferous amphibolite, gneiss, metapelite and calc-silicate rocks. They are most abundant at the top of the Mafic Zone, particularly where the Upper Sequence is absent (Correia et al., 2012; Giovanardi et al., 2016).
Upper Sequence
• Upper Gabbro-Anorthosite Zone, olivine gabbros, grading to anorthosites and troctolites, with local layers and lenses of subophitic, coarse grained, isotropic gabbros.
• Upper Amphibolite, comprising amphibole-bearing gabbros, interlayered with amphibolite, epidote-bearing gneiss and/or other lithologies of the overlying Palmeirópolis/Indaianópolis/Juscelândia meta-volcanic and meta-sedimentary sequences. The contact with these latter sequences is magmatic for all the complexes and in both the Lower and Upper Sequence (Correia and Girardi, 1998; Ferreira Filho et al., 2010; Girardi and Kurat,1982; Girardi et al., 1986).
The ~15 km diameter, Neoproterozoic Uruaçu Complex is located toward the southwestern margin of the terrane (not shown in Figs. 1 or 2). It is structurally complex, mainly composed of quartz dioritic orthogneiss and sillimanite-cordierite-bearing paragneiss. Orthogneiss dominates and is generally strongly deformed and migmatised. It is associated with mafic and ultramafic rocks composed of garnet-amphibolite, and fine- to medium-grained schist, with cummingtonite, actinolite, talc, magnesite, garnet and clinochlore that are not aligned. Paragneiss occurs as medium- to coarse-grained banded granulite, with alternating sillimanite-cordierite rich layers and quartz-feldspar bands containing spinel and quartz, an assemblage representative of ultrahigh-temperature metamorphism (UTM). Garnet-bearing quartz-feldspar-biotite-chlorite-muscovite rock is also common. The complex is interpreted to have undergone diapiric ascent as a metamorphic core complex within the Campinorte Terrane. U-Pb geochronology indicates the orthogneiss, amphibolite and migmatite crystallised between ~690 and 651 Ma (Giustina et al., 2009). Detrital zircon grains from a single paragneiss sample returned ages mostly in the range between 800 and 760 Ma with zircon overgrowths indicating metamorphic ages of ~650 Ma, consistent with the metamorphic/recrystallisation age above (Giustina et al., 2009; Pimentel 2016). The complex, formed from Neoproterozoic intrusives and sedimentary rocks, appears to have structural contacts with the Archaean Hidrolina Complex, the Palaeoproterozoic Campinorte Sequence and the Mesoproterozoic Serra da Mesa Group. This requires a complex structural history involving a contractional Neoproterozoic inversion that overturned or imbricated the sequence between the extensional phase that had culminated in the 1.26 to 1.30 Ga Palmeirópolis, Indaianópolis and Juscelândia volcano-sedimentary successions, and the subsequent extension reflected by emplacement of the 800 to 770 Ma Barro Alto, Niquelândia and Cana Brava complexes and emplacement of the Uruaçu metamorphic core complex at ~650 Ma. This contraction and imbrication on, and between, the Rio dos Bois and Rio Maranhão thrusts led to uplift and absence of deposition over much of the Campinorte Terrane.

Campinorte Terrane References
Cordeiro, P.F.O., Oliveira, C.G., Della Giustina M.E.S., Dantas, E.L. and Santos, R.V., 2014 - The Paleoproterozoic Campinorte Arc: Tectonic evolution of a Central Brazil pre-Columbia orogeny; Precambrian Research, v.251, pp. 49-61.
Della Giustina M.E.S., Oliveira, C.G., Pimentel, M.M., Melo, L.V., Fuck, R.A., Dantas, E.L. and Buhn, B., 2009 - U-Pb and Sm-Nd constraints on the nature of the Campinorte sequence and related Palaeoproterozoic juvenile orthogneisses, Tocantins Province, central Brazil;in Reddy, S.M., Mazumder, R., Evans, D.A.D. and Collins, A.S. (Eds.), Palaeoproterozoic Supercontinents and Global Evolution. Geological Society, London, Special Publications, v.323, pp. 255-269.
Della Giustina M.E.S., Oliveira, C.G., Pimentel, M.M. and Buhn, B., 2009 - Neoproterozoic magmatism and high-grade metamorphism in the Goiás Massif: New LA-MC-ICMPS U-Pb and Sm-Nd data and implications for collisional history of the Brasília Belt; Precambrian Research, v.172, pp. 67-79.
Cordeiro, P.F.O., Oliveira, C.G., Giustina, M.E.S.D., Dantas, Santos, R.V.,2014 - The Paleoproterozoic Campinorte Arc: Tectonic evolution of a Central Brazil pre-Columbia orogeny, Precambrian Research, v.251, pp. 49-61.
Giovanardi, T., Girardi, V.A.V., Correia, C.T., Tassinari, C.C.G., Sato, K., Cipriani, A. and Mazzucchelli, M., 2017 - New U-Pb SHRIMP-II zircon intrusion ages of the Cana Brava and Barro Alto layered complexes, central Brazil: constraints on the genesis and evolution of the Tonian Goias Stratiform Complex; Lithos v.282-283, pp. 339-357.

Cavalcante-Arraias Terrane
This terrane is limited to the west, south and east by the Rio Maranhão thrust, which separates it from the structurally overlying Campinorte Terrane to the west, and thrusts it over the Meso- to Neoproterozoic Bras&iacut;lia Belt metasedimentary cover rocks to the south. To the east, the same east vergent thrust juxtaposes it over the Neoproterozoic Bambuí Group shelf sequence, which is, in turn, masked by the Cretaceous Urucuia Basin further to the east. In the NW, it is overthrust by the the Neoproterozoic Goias Magmatic Arc across the Rio dos Bois Thrust, whilst to the NE it structurally overlies the Almas-Conceição do Tocantins Terrane.
The terrane is predominantly composed of peraluminous metagranitoids of the Paleoproterozoic Aurumina Suite, which intrude biotite-garnet paragneiss, migmatite and mica-graphite schist of the Ticunzal Formation (Cordeiro and Oliveira, 2017). The latter formation yields detrital zircons with U-Pb and Nd model ages of between 2.23 and 2.88 Ga (Cuadros et al., 2017), whilst other Zircon U-Pb geochronology and field observations suggest the precursor sedimentary rocks were deposited between 2.16 and 2.19 Ga. Peak metamorphic temperatures of the Ticunzal Formation are indicated at between 620 and 630°C, whilst trace element geochemistry suggests these precursor sediments were deposited during the Rhyacian in a continental arc-related basin on the western margin of the S&ati;lde;o Francisco Craton (Cuadros et al., 2017).
The Aurumina Suite is composed of a range of intrusives, including muscovite granite, biotite-muscovite granite, tonalite, biotite granite and tourmaline-muscovite granite, accompanied by pegmatites, albite granites and rare albitites (Sirqueira et al., 2018). These metagranitoids and associated rocks are roughly coeval with those of the Campinorte Sequence Campinorte Terrane, as shown by crystallisation ages in the former of from 2183 ±24 to 2136 ±3 Ma from metagranites, and 2042 ±12 Ma for a tonalite intrusion (Fuck et al., 2014). However, the strongly peraluminous composition and syn-tectonic geochemical signature the Aurumina Suite muscovite granites are incompatible with those of the Campinorte Domain Pau de Mel Suite. Compositional features of the Aurumina Suite and associated coeval metaluminous mafic to intermediate plutons have led Cuadros et al. (2017) to conclude a source that involved hybridisation characterised by a shallow depth (pressure of <5 kbar, i.e., a high temperature-low pressure regime) reaction between metasedimentary rocks and basaltic melts. In this context, Botelho et al. (2006) suggests the hybridisation that formed the Aurumina Suite magmatism involved reworking of the Ticunzal Formation. This would be consistent with post-collisional relaxation, delamination and detachment, followed by asthenospheric upwelling, mafic underplating and melting of the overlying crust.
These early to mid Palaeoproterozoic Rhyacian rocks were eroded and covered by the rift-related, predominantly sedimentary rocks of the late Palaeo- to Mesoproterozoic, 1.7 to 1.5 Ga, Araí Group, that include rhyolitic volcanic rocks dated at 1771 Ma (Pimentel et al., 1991). The Araí Group is a 1500 m thick sequence, divided into two formations. The basal section is represented by the Arraias Formation, which consists of quartzite with intraformational conglomerate units, intercalated with siltstones and sub-alkaline, bimodal volcanism, composed of basalt, rhyodacite/dacite and rhyolite volcanic and volcaniclastic rocks with tholeiitic affinities (Silva et al., 2017). The overlying Trairas Formation comprises a thick pile of shallow-marine sandstone, siltstone, pelite and minor carbonate units (Fuck et al., 2000; Cordani et al., 2000). The Araí Group temporally overlaps similar rift related sequences of the Serra da Mesa Group of the Campinorte Terrane to the NW and the Espinhaço Supergroup of the São Francisco Craton to the east.
The bimodal volcanism of the Araí Group was accompanied by the coeval Pedra Branca Suite and Sucuri granites to the east that have been dated at 1767 ±10 Ma and 1769 ±2 Ma, respectively. Toward the west, the Araí Group is intruded by granitoids interpreted to be related to the 1658 and 1574 Ma Mesoproterozoic A-type granites of the Serra da Mesa Suite found in the Campinorte Terrane.

Cavalcante-Arraias Terrane References
Cuadros, F.A., Botelho, N.F., Fuck, R.A., Dantas, E.L., 2017 - The Ticunzal Formation in central Brazil: Record of Rhyacian sedimentation and metamorphism in the western border of the São Francisco Craton; Journal of South American Earth Sciences, v.79, pp. 307-325.
Cordeiro, P.F. de O. and Oliveira, C.G., 2017 - The Goiás Massif: Implications for a pre-Columbia 2.2-2.0 Ga continent-wide amalgamation cycle in central Brazil; Precambrian Research, v.298, pp. 403-420.
Cordeiro, P.F.O., Oliveira, C.G., Della Giustina, M.E.S., Dantas, E.L. and Santos, R.V., 2014 - The Paleoproterozoic Campinorte Arc: Tectonic evolution of a Central Brazil pre-Columbia orogeny, Precambrian Research, v.251, pp. 49-61.
Fuck, R.A., Dantas, E.L., Pimentel, M.M., Botelho, N.F., Armstrong, R., Laux, J.H., Junges, S.L., Soares, J.E. and Praxedes, I.F., 2014 - Paleoproterozoic crust-formation and reworking events in the Tocantins Province, central Brazil: A contributionfor Atlantica supercontinent reconstruction; Precambrian Research, v.244, pp. 53-74. doi.org/10.1016/j.precamres.2013.12.003.

Almas-Conceição do Tocantins Terrane
This terrane represents the northeastern extremity of the Gois Massif and is bounded to the south and west by a thrust plane that separates it from the structurally overlying Palaeoproterozoic rocks of the Cavalcante-Arraias Terrane which is mainly composed of meta-granitoids of the 2.16 to 2.12 Ga Aurumina Suite (Saboia et al., 2020 and references cited therein). To the north it is overlain by the Palaeozoic Parnaíba and Mesozoic Urucuia basins and in the east, it is thrust with an eastward vergence over the Neoproterozoic Bambuí Group shelf sequence developed on the margins of the São Francisco Craton. It is defined by a network of folded narrow, up to 4 km wide, greenstone belt keels, surrounded by Palaeoproterozoic gneissic TTG complex domes.
The Greenstone belt sequences are the oldest exposed units of the terrane and comprise the Riachão do Ouro Group which is subdivided into the: i). basal Córrego do Paiol Formation composed of metamorphosed pillowed basaltic flows with subordinate ultramafic lenses; and ii). the overlying Morro do Carneiro Formation with interbedded phyllites, banded iron formations, quartzites, meta-cherts, meta-conglomerates and felsic meta-volcanic rocks (Saboia et al., 2020 and references cited therein). The minimum age of the group is indicated by its xenoliths found within the ~2.45 Ga granitoids of the Ribeirão das Areias Complex (Cruz et al., 2003).
The Riachão do Ouro Group was intruded by two main Siderian plutonic episodes (after Saboia et al., 2020):
i). the Ribeirão das Areias Complex, an early suite dominated by tonalites and trondhjemites with subordinate granodiorite and biotite granite. It has been dated at 2455 ±14 Ma (U-Pb titanite; Cruz et al., 2003). This intrusive suite is biotite-rich, includes both high- and low-Al types and high- and medium-pressure metamorphic lithologies;
ii). the ~2.30 Ga Ribeirão Itaboca Suite which included tonalites and trondhjemites that comprise high-Al types and the medium pressure metamorphic rocks. These Siderian intrusives are regarded as a relict of a more widespread tonalitic basement to the Almas-Conceição do Tocantins Terrane (Cruz et al., 2003).
These are in turn cut by the extensive 2.3 to 2.16 Ga Rhyacian Conceição do Tocantins Suite that include (after Saboia et al., 2020 and references cited therein):
- an ~2.29 Ga Monzogranite Unit - medium to coarse grained, inequigranular to porphyritic, foliated to mylonitic, monzogranite to syenogranite;
- an ~2.28 Ga Quartz-dioritic Suite - medium to coarse grained, inequigranular to granoblastic, foliated and banded, composite quartz-diorite-gabbro-tonalite complex;
- an ~2.26 → 2.16 Ga Granodioritic to Tonalitic Suite - coarse to fine grained, inequigranular and porphyritic rocks with a wide range of crystallisation forms that are foliated to mylonitic and include granodiorite, tonalite, quartz-diorite and monzogranite;
- the 2.22 → 2.21 Ga Serra do Boqueirão Suite - medium to coarse grained, inequigranular, hypidiomorphic and granoblastic, foliated tonalite; and
- a 2.2 → 2.18 G Ma Peraluminous Suite - medium to coarse grained, inequigranular, equigranular and porphyritic, hypidiomorphic, xenomorphic to granoblastic and foliated → protomylonite and banded granodiorite, tonalite, leuco-tonalite to monzogranite.
Of the five suites recognised, only the second, the Quartz-dioritic Suite, is magnetic, while the main mafic phase varies from the first to last, from biotite → hornblende-biotite → biotite-hornblende → hornblende → biotite respectively.
These intrusions were followed by Gameleira Suite, which comprises a number of medium and small mafic to ultramafic layered plutons composed of meta-gabbros, meta-peridotites, meta-pyroxenites and serpentinites intruding greenstones, and both Siderian and Rhyacian intrusive rocks. The intruded rocks are all gneissic to migmatitic (Correia Filho and Sá, 1980). The mafic rocks of the Gameleira Suite are interpreted to be associated with an extensional magmatic event following the Siderian period. They contain abundant zircon, interpreted to be crustal contamination, with dominant ²⁰⁷Pb/²⁰⁶Pb age populations of 2.48 and 2.30 Ga (Saboia et al., 2020, and references cited therein).
Towards the west and southwest, the units described above are in tectonic contact with, or are overlain by, the ~2.17 Ga metavolcano-sedimentary Água Suja Group (Saboia et al., 2020). This group straddles the boundary with the adjacent Cavalcante-Arraias Terrane to the west (Saboia et al., 2020) and comprises quartzites, pelites, carbonaceous phyllite, gondite, chert, banded iron formation and rare mafic volcanic rocks. It may possibly be a temporal equivalent of the Ticunzal Formation that is mapped in the adjacent Cavalcante-Arraias Terrane (Sousa, 2015). Within the same southwestern quadrant of the Almas-Conceição do Tocantins Terrane, the Rhyacian and Siderian granitoids are intruded by lithofacies interpreted to belong to the Aurumina Suite which is widespread throughout the Cavalcante-Arraias Terrane and has been described for that terrane above. Within the Almas-Conceição do Tocantins Terrane, lithofacies of this suite have yielded dates of 2180 ±12 Ma for a tonalite and 2144 ±21 Ma for a coarse grained foliated biotite granite.
The northwestern quadrant of the terrane is covered by an extensive area of the Late Palaeoproterozoic to Mesoproterozoic Natividade Group. This group is interpreted to represent deposition in an intracontinental sag-type basin in which the sedimentary environment resulted in massive carbonate accumulation on a complex platform controlled by the basement palaeo-relief, along with a mixed siliciclastic platformal and shallow water turbidite facies. Sedimentation is interpreted to have occurred between the deposition of the Araí Group of the Cavalcante-Arraias Terrane and the Serra da Mesa group of the Campinorte Terrane, but occurs within the wider temporal range of the Espinhaço Supergroup of the São Francisco Craton and its margins. It is noted for the absence of continental sediments characteristic of the Araí Basin, and the lack of detrital zircon grains younger than 1.5 Ga which are found in the Serra da Mesa groups. A felsic meta-volcanic sample from the Natividade Group yielded a U-Pb zircon age 1824 Ma, while the youngest detrital zircon grains from the meta-sedimentary sequence were dated at 1776 Ma (Silviera et al., 2020).

The Goiás Massif represents structurally uplifted continental margin basement that defines the western limit of the Neoproterozoic Brasiliano sequences. Most of the terranes of the massif were formed during the Siderian and Rhyacian of the Palaeoproterozoic, partly or wholly on an Archaean basement. The timing of the amalgamation of the Goiás Massif and São Francisco Craton has been a matter of conjecture as to whether it occurred in the Palaeo- or Neoproterozoic (e.g., as discussed by Cordeiro and Oliveira, 2017). A potential suture zone has been hypothesised as the surface trace of the Rio Maranhão Thrust which corresponds to a sharp crustal thinning from east to the west. Studies reported in Cordeiro and Oliveira (2017) are interpreted by those authors to indicate Goiás Massif terranes that underwent orogenesis between 2.2 and 2.0 Ga, have similar geological features on either side of the Rio Maranhão Thrust, and show no evidence of syn-collisional Neoproterozoic magmatism. They suggest that i). the crustal thinning along the Rio Maranhão Thrust, as indicated by a sustained gravimetric contrast, represents a Neoproterozoic lower crustal delamination and detachment event that affected both the Brasiliano Orogen to the SE and the Campinorte Arc; ii). the Serra da Mesa Suite of Mesoproterozoic granites intruded both sides of the Rio Maranhão Thrust, indicating the two domains were already amalgamated at that time; iii). Rhyacian arc magmatism dated at 2157 ±9 to 2147 ±5 Ma found in the basement of the Brasilia Belt sequence in the Artulândia area to the south of the Rio Maranhão Thrust, are similar to that of the Campinorte Arc in the Goiás Massif to the north, suggesting the massif was amalgamated with the São Francisco Craton prior to the Mesoproterozoic (Filgueiras, et al., 2020); iv). Mesoproterozoic volcanic and plutonic rocks follow the trace of the Rio Maranhão Thrust, suggesting a reactivated intracontinental structure rather than an original product of a later Brasiliano collision; v). the Goiás Massif exhibits key similarities to the São Francisco Craton, including orogen building and magmatism between 2.2 and 2.0 Ga; metamorphic peaks from 2.11 to 2.08 Ga; zircon age peaks at ~1.76, ~1.58 and ~1.2 Ga, largely accompanying to crustal extension events, and contiguous seismic signatures from massif to craton. Cordeiro and Oliveira (2017) conclude these common features, taken in conjunction with their reassessment of central Brazilian geochronology, and the nature of the sharp crustal thickness contrast in Central Brazil, all indicate that the Goiás Massif was fully assembled during a 2.2 to 2.0 Ga Orogeny as part of the western margin of the São Francisco(-Congo) palaeocontinent. Similarly, detailed geophysical data analysed by Reis (2019) indicate the Rio Maranhão Fault constitutes an intracontinental structure without depth expression, whilst in contrast, the Rio dos Bois Fault System is a region of discontinuity, indicating a suture zone between the Goiás Massif and the Goiás Magmatic Arc (see below>)
A magnetotelluric survey beneath the northern Brasília belt (Padilha et al., 2013), revealed a huge high conductivity anomaly below the entire Goiás Massif centred immediately to the west of the crustal thinning zone marked by the Rio Maranhão Thrust. This anomaly is predominantly concentrated at the uppermost mantle but also affects mid to lower crustal depths. Padilha et al. (2013) interpreted this anomaly to be associated with thermal events either related to the long-lived Meso- to Neoproterozoic continental rifting processes or to delamination and detachment processes at the end of the evolution of the belt, in the Neoproterozoic.

Goiás Massif and Almas-Conceição do Tocantins Terrane References
Filgueiras, B.C., Oliveira, C.G., Sousa, I.M.C., Cordeiro, P., 2020 - Further evidence of Rhyacian arc magmatism in the basement of the Brasília Belt, western São Francisco pericraton; Journal of South American Earth Sciences, v.103, doi.org/10.1016/j.jsames.2020.102739.
Padilha, A.L., Vitorello, I. and Pádua, M.B., 2013 - Deep conductivity structure beneath the northern Brasília belt, central Brazil: Evidence for a Neoproterozoic arc-continent collision; Gondwana Research, v.23/2, pp. 748-758.
Reis, L.K.O., 2019 - Tectonic Framework of the Central Portion of the Brasília Belt; 16th International Congress of the Brazilian Geophysical Society, Rio de Janeiro, Brazil, 19-22 August 2019; 5p.
Saboia, A.M., 2021 - Geologia, Geocronologia e Geoquímica dos Granitoides Paleoproterozoicos do Domínio Almas-Conceição do Tocantins, Norte do Orógeno Brasília: Implicações Magmáticas e Geodinâmicas; Thesis presented to the Graduate Program in Geology at the University of Brasília, as a partial requirement for obtaining the degree of Doctor in Geology. 126p.
Saboia, A.M., Oliveira, C.G., Dantas, E.L., Scandolara, J.E., Cordeiro, P., Rodrigues J.B. and Sousa. I.M.C., 2020 - The 2.26 to 2.18 Ga Arc-Related Magmatism of the Almas-Conceição do Tocantins Domain: An Early Stage of the São Francisco Paleocontinent Assembly in Central Brazil; Journal of South American Earth Sciences, v.104. doi.org/10.1016/j.jsames.2020.102757.
Saboia, A.M., Oliveira, C.G., Dantas, E.L., Scandolara, J.E., Cordeiro, P., Rodrigues J.B. and Sousa. I.M.C., 2020b - The Siderian crust (2.47-2.3 Ga) of the Goiás Massif and its role as a building block of the São Francisco paleocontinent; Precambrian Research, v.350, doi.org/10.1016/j.precamres.2020.105901.
Toscania, R., Campos, J.E.G., Martins-Ferreira, M.A.C., Matos, D.R., Borges, C.C.A., Dias, A.N.C. and Chemale, F., 2021 - The Statherian Natividade Basin evolution constrained by U-Pb geochronology, sedimentology, and paleogeography, central Brazil; Journal of South American Earth Sciences v.112, Part 2, doi.org/10.1016/j.jsames.2021.103618.

GOIÁS MAGMATIC ARC

The Early Neoproterozoic Goiás Magmatic Arc was formed on the outer western and south western margin of the São Francisco palaeocontinent, which by the late Mesoproterozoic is interpreted to have included the accreted Goiás Massif (Cordeiro and Oliveira, 2017). It is divided into two segments, separated by the Crixás-Goiás Terrane of the southwestern Goiás Massif. The northern of these segments is the NNE-SSW elongated Mara Rosa Arc, which is bounded to the west by the Araguaia Belt, and to the east by the amalgamated São Francisco Craton and Goiás Massif. The second is the NNW-SSE trending Arenópolis Arc to the SW, on the southwestern margin of the Brasilia Belt, between the São Francisco Craton to the NE and the Paranápanema Block to the SW. The latter block is concealed below deep Phanerozoic cover of the Paraná Basin.
In both segments, the arc is interpreted to have been initiated as an ~920 to 800 Ma intra-oceanic arc (Carneiro et al., 2021 and references cited therein; Pimentel and Fuck 1992), whilst the final widespread continental magmatic event took place in two pulses, between ~650 and 600, and at ~500 Ma (Carneiro et al., 2021 and references cited therein; Cordani et al., 2013). The Goiás Magmatic Arc is represented by i). supracrustal volcano-sedimentary sequences, ii). orthogneiss after calc-alkaline plutonic rocks, and iii). bimodal, post-tectonic metamorphosed granitic intrusions that range from gabbro to granite, as follows:
• Supracrustal sequences of calc-alkaline meta-volcanic rocks and feldspar-bearing mica schist with minor quartzite and marble (Pimentel, 2016). In the Mara Rosa-Chapada (i.e., central) section of the Mara Rosa Arc, the supracrustal rocks comprise metabasalt, intermediate and felsic meta-tuffs, fine-grained meta-greywacke, garnet-mica schist, chert, iron formation, quartzite and ultramafic rocks that have been metamorphosed to greenschist to amphibolite facies. Small bodies of mylonitised granites occur within the sequence. The amphibolites within the sequence are either tholeiitic, rich in Mg, Ni and Cr and similar to boninites, or calc-alkaline, interpreted (Palermo, 1996) to represent fragments of oceanic crust and arc magmatism respectively. The sequence is interpreted to have formed at ~860 Ma in the Tonian (Delgado et al., 2002). Feldspathic garnet-mica schist and fine grained biotite gneiss, representing detrital metasedimentary rocks, yield TDM ages of predominantly ~1.2 to 0.9 Ga, interpreted to indicate a provenance from erosion of arc rocks, distant from any old continental source. Sm-Nd garnet-whole rock isochrons for these metasediments indicate ages of ~765, 733, 604 and 610 Ma, interpreted as indicating two metamorphic episodes at ~750 and ~605 Ma (Pimentel, 2000). In the Mara Rosa-Chapada area, the Mara Rosa Arc comprises three narrow NNE trending belts defined by bands of metabasalt and of detrital metasediments (quartzite and garnet-feldspar-mica schist), with minor chert and talc schist. These bands are separated by ESE vergent thrust faults and by bands of tonalitic to granodioritic orthogneisses that have been metamorphosed to upper greenschist and amphibolite facies. These are overprinted by irregularly distributed plutons of post-orogenic gabbro-diorite and granite (Matteini, et al., 2010). The Mara Rosa Arc is parallel to the regional structural fabric and is thrust to the ESE over the Goiás Massif, as well as being disrupted by the >4000 km dextral Transbrasiliano Lineament that was periodically active from the Neoproterozoic to the Mesozoic continental break-up.
Whilst the Arenópolis Arc is aligned in an overall NW-SE direction, it is composed of a series of NNW-SSE to NNE-SSW aligned strips of supracrustal sequences separated by east-dipping thrusts, regional shears with similar trends, and by bands of gneiss, orthogneiss and granitoids. There are at least 5 deformed strips of ~900 Ma to 600 Ma metavolcano-sedimentary sequences, arranged without a clear chronologic gradient. Each of these sequences represent a different arc-related basin or basin segment. They are exposed in two structural domains, divided by the Moiporá-Novo Brasil Lineament (Fig. 2) which follows the western limit of the Crixás-Goiás Terrane. The eastern domain encompasses ~800 Ma calc-alkaline tonalite gneisses and ~600 Ma mafic and granitic intrusions, with associated Neoproterozoic metavolcanic-sedimentary sequences (Laux et al., 2004, 2005). The western domain is exposed in an erosive window through the Paraná Basin, where several strips of supracrustal rocks are exposed between orthogneisses with ages varying from ~900 to ~600 Ma. Deformation in this domain is accommodated by NNW-SSE shear zones, whilst the westernmost limit is marked by the NE-SW Transbrasiliano Lineament separating it from Paraguaia Belt rocks (Seer, 1985; Curto et al., 2014). The main volcano-sedimentary strips vary from the westernmost Bom Jardim de Goiás Sequence where a lower unit of greenschist facies meta-basalt, meta-andesite and meta-rhyolite is overlain by an upper detrital sedimentary unit of mainly meta-conglomerate, meta-arkose, meta-siltstone and phyllite (Seer 1985). Further east, the Arenópolis Sequence (Pimentel and Fuck 1986) is divided into two. The western succession (the Córrego da Onç unit) of mainly garnet, staurolite, kyanite and sillimanite bearing metapelite, marble, calc-silicate rocks, metachert, gondite and mafic-ultramafic bodies is interpreted to represent an accretionary complex. It is separated by a narrow wedge of strongly deformed Palaeoproterozoic banded gneiss (the Ribeirão Gneiss), from the eastern succession, (the Córrego do Santo Antônio unit) that is dominantly composed of very primitive calc-alkaline meta-volcanic rocks including meta-basalt, meta-andesite, meta-dacite and meta-rhyolite, with lesser low-K meta-tholeiite, meta-greywacke, fine-grained quartzite and meta-chert; an ~929 Ma age of formation and ~594 Ma metamorphism is quoted for this succession (U-Pb; Pimentel (1985). The volcano-sedimentary sequences progressively to the east next include the Iporá-Amorinópolis and Jaupaci strips that are deficient in intermediate volcanic rocks, mainly composed of bimodal suites (Pimentel et al., 2000; Carniero et al., 2021 and references cited therein), with ages of 636 ±6 and 597 ±5 Ma (U-Pb; Pimentel et al. 2000) for the former, and for the latter, an age of formation of ~764 Ma and metamorphism at ~600 Ma (Amaro, 1989; Pimentel and Fuck, 1994; Pimentel, 1985). Felsic volcanic rocks with psammitic and psammo-pelitic rocks of the Mossâmedes Sequence, east of the Moiporá-Novo Brasil Lineament, are indicated to be ~750 Ma by Carniero et al. (2021), although dating by Pimentel et al. (1996) returned Palaeo- to Mesoproterozoic ages suggesting they were part of the Goiás Massif. The Anicuns-Itaberaí Sequence further to the east is composed of meta-pelitic to meta-psammitic rocks, occurring as biotite-chlorite-muscovite schist, muscovite-quartz schist, biotite-graphite shale, muscovite-biotite schist, kyanite-muscovite-sericite-chloritoid schist, quartzite, metachert, iron formation and ultramafic and amphibolite lenses, with metre to kilometre scale lenses of magnesian to dolomitic marbles and associated orthogneiss and garnet-biotite schist. Carniero et al. (2021) regard these as early Neoproterozoic, Tonian, while an age of ~860 Ma is quoted by Barbosa (1987) and Pimentel et al. (2000).
• Calc-alkaline plutonic rocks that have been variably deformed and metamorphosed to orthogneiss, ranging from gabbro to granite, with a large volume of tonalite (Arantes et al., 1991). The orthogneiss derived from these igneous protoliths are predominantly hornblende-bearing meta-diorite, meta-tonalite and meta-granodiorite compositions. Most have an Nd model age of between 0.8 and 1.1 Ga (Pimentel et al., 1991, 1997, 2000; Pimentel and Fuck 1992), whilst U-Pb zircon ages suggest the igneous protholits crystallised in three main events (Pimentel, 2016):
i). between ~900 and 804 Ma, in both the juvenile Mara Rosa and Arenópolis orthogneisses (Pimentel et al., 1991; Pimentel and Fuck 1992). In the Mara Rosa-Chapada area, these are medium- to coarse-grained dioritic to tonalitic meta-plutonic rocks that are geochemically very primitive with SiO2 levels of <60% and a calcic to calc-alkaline character. Protolith crystallisation dates of 856 13 Ma are indicated (U-Pb zircon; Pimentel et al., 2000), whilst Nd isotopic data imply a very primitive original magma, with TDM ages of ~0.9 to 1.0 Ga. Mylonitic orthogneiss bands with Archaean model ages ranging from 2.9 to 3.1 Ga occur within the arc, which is cut longitudinally by the continental scale Transbrasiliano Lineament. These suggest structural interleaving of basement. Calcic to calc-alkaline orthogneisses in the Arenópolis Arc are hornblende- and biotite-bearing meta-tonalites and meta-granodiorites with mineral assemblages indicative of metamorphism at epidote-amphibolite facies. They commonly exhibit relict igneous textures and structures, such as mafic enclaves, porphyritic textures and magma mixing features. Major and trace element data suggest that the igneous protoliths were metaluminous, calcic- to calc-alkaline, with high CaO, MgO, P2O5 and Al2O3 (Pimentel 1991). Other geochemical characteristics are comparable with values found in primitive M-type granitoids of intraoceanic island arcs (Pimentel et al., 2000).
ii). The second event is represented by peraluminous muscovite-bearing metagranitoids generated between 790 and 786 Ma in the easternmost part of the Arenópolis Arc, with TDM model ages in the range between 1.46 and 1.1 Ga (Laux et al., 2005).
iii). The late two pulse event represents extensive continental magmatism that began with the interval between 669 and 630 Ma, represented by metaluminous gneisses with U-Pb emplacement ages between 637 and 630 Ma (Laux et al., 2005). The Nd isotopic signature is varied with TDM model ages in two populations, of ~0.99 Ga, and between 1.1 and 2.2 G.a (Laux et al., 2005). The second pulse produced large, bimodal, post-tectonic granitic intrusions found in both the Arenópolis and in the Mara Rosa arcs. They range in age between ~630 and 540 Ma. In the Arenópolis arc, they are mainly metaluminous, high-K calc-alkaline to alkaline (A-type) granites associated with small gabbrodioritic bodies, whereas in the Mara Rosa arc, peraluminous granite intrusions are also recognised (Pimentel, 2016).
It would seem likely that the Goiás Magmatic Arc was initiated above a curved (or two separate) intra-oceanic subduction zone(s) that dipped to the west below the Amazonian Craton in the north, and to the SW below the Paranápanema Block in the south, producing the Mara Rosa and Arenópolis arcs respectively. In the north, the Mara Rosa Arc progressed to the east on the advancing oceanic crust on the leading edge of the Amazonian plate, converging on the passive margin of the São Francisco palaeocontinent. This convergence had progressed from some time after ~1.2 Ga in the Stenian of the late Mesoproterozoic. The Goiás Massif represented the forward margin of the São Francisco palaeocontinent, having been accreted during the Palaeoproterozoic. This subduction persisted until the intraoceanic arc collided with and overrode the São Francisco palaeocontinent passive margin by ~800 Ma. Collision was followed by the complex east vergent thrusting that resulted in the Rio dos Bois, Rio Maranhão and related thrusts. The collision, imbrication and crustal thickening led to the Goiás Massif being down-thrust to depth resulting in the formation of high temperature metamorphic assemblage, migmatisation and anatexis. This was followed by tectonic relaxation, and to slab-break-off, delamination and detachment of the subcrustal lithospheric mantle (SCLM) to the west of the Rio Maranhão Thrust. Detachment was followed by concomitant uplift of the crust, unburdened by the detached denser SCLM, asthenospheric upwelling and its decompression melting. This led to the emplacement of the 800 to 770 Ma Barro Alto, Niquelândia and Cana Brava layered mafic complexes in the Goiás Massif, guided by the active Rio Maranhão Thrust.
During this period, the Arenópolis Arc, which was on the leading edge of the plate ahead of the Paranápanema Block, advanced overall to the east to ENE, towards the passive margin of the São Francisco palaeocontinent, represented by the Brasilia Belt shelf sequence (described below). This continued advance also led to further oblique contraction of the Mara Rosa Arc and Goiá Massif and reactivation of the Rio dos Bois, Rio Maranhão thrust system, particularly along the base of the Barro Alto, Niquelândia and Cana Brava layered mafic complexes. It also affected the northwestern extremities of the Arenópolis Arc which was dislocated by thrusting, the result of the interaction of NW-SE and NE-SW vectors of contraction produced by the advance of the Paranápanema Block relative to the Amazonian and São Francisco cratons. This led to the dislocation of the NW-SE elongated Arenópolis Arc by NNE to NNW striking thrusts. Magmatism also persisted longer on this reactivated arc, generating 790 and 786 Ma granitoids until collision at ~750 Ma. Collision was followed by imbrication, as the Brasilia Belt passive margin was thrust below the advancing Arenópolis Arc until ~630 Ma. This resulted in the 670 to 630 Ma continental arc magmatism, when the degree of imbrication and crustal thickening were sufficient to promote anatexis and high pressure and temperature metamorphism, although not as intense as that accompanying the Mara Rosa Arc, but was sufficient to develop epidote amphibolite facies metamorphic assemblage. Compression and thickening were followed by compensatory tectonic relaxation, rebound and a subsequent phase of extension that lasted from ~630 to 540 Ma, resulting in crustal attenuation, uplift, asthenospheric upwelling, anatexis, voluminous bimodal granitoids and eventually the exposure of previously deeply buried high temperature metamorphic suites. The extensional tectonics also led to the emplacement of the Uruaçu metamorphic core complex in the Campinorte Terrane at ~650 Ma.

Goiás Magmatic Arc References
Carneiro, J., Fuck, R. and Dantas, E.L., 2021 - Arenópolis sequence, evolution of a marginal basin in the Neoproterozoic Goiás magmatic arc, central Brazil; Journal of South American Earth Sciences, v.106, doi.org/10.1016/j.jsames.2020.103033.
Delgado, I.M. et al., 2003 - Geotectonics of the Atlantic Shield; in Bizzi, L.A., Schobbenhaus, C., Vidotti, R.M. and Gonçalves J.H., (eds.), Geologia, Tectônica e Recursos Minerais do Brasil, CPRM, Serviço Geológico do Brasil Brasília, pp. 227-334.
Matteini, M., Junges, S.L.,Dantas E.L., Pimentel M.M. and Buhn, B., 2010 - In situ zircon U-Pb and Lu-Hf isotope systematic on magmatic rocks: Insights on the crustal evolution of the Neoproterozoic Goias Magmatic Arc, Brasília belt, Central Brazil; Gondwana Research, v.17, pp. 1-12.
Pimentel, M.M., 2016 - The tectonic evolution of the Neoproterozoic Brasília Belt, central Brazil: a geochronological and isotopic approach; Brazilian Journal of Geology, v.46, pp. 67-82.
Pimentel, M.M., Fuck, R.A. and Gioia S.M.C., 2000 - The Neoproterozoic Goiás Magmatic Arc, Central Brazil: a review and new Sm-Nd isotopic data; Revista Brasileira de Geociências, v.30/1, pp. 35-39.

BRASILIA FOLD BELT

The Brasilia Fold Belt is exposed over a >1000 km long, NNW elongated, north-tapering, wedge-shaped belt. It lies to the west of the São Francisco Craton and to the east of the Goiás Massif, bounded to the SW by the Arenópolis Arc and the overlying Paraná Basin. It overlies an Archaean to Palaeoproterozoic basement reflected by the rocks of the Goiás Massif which were most likely accreted to the western margin of the São Francisco Craton during the Orosirian epoch of the Palaeoproterozoic (e.g., Cordeiro and Oliveira, 2017). However, some authors still maintain this amalgamation did not occur until the late Neoproterozoic (e.g., Pimentel, 2016). The main stratigraphic units are generally bounded by west-dipping regional thrusts, reverse faults and nappes, all indicating east vergence (e.g., Valeriano et al., 2012). The reconstruction of the original setting and age of the basin has been rendered uncertain by the strong deformation and concomitant structural disruption, and by the general absence of intercalations of dateable volcanic rocks. Dating of detrital zircon ages have largely been used to construct a temporal framework.
The deformation of the Brasilia Fold Belt has been interpreted to represent an east to NE vergent thin-skinned fold-thrust belt where major thrusts, including the Rio dos Bois and Rio Maranhão thrusts that straddle the Goiás Massif, and the Rio Paranã thrust that marks the transition to cratonic basement further east, all converge at depth into a sole thrust detachment. This detachment overlies a basement of Archaean to Palaeoproterozoic crystalline rocks (e.g., Reis et al., 2020; Westin et al., 2019).
The principal stratigraphic units of the Brasilia Belt are as follows:

Paranoá Group - which comprises a mature siliciclastic sedimentary pile that commences with a basal paraconglomerate, followed by transgressive and regressive siliciclastic cycles that include thick quartzite layers, with intercalations of meta-siltstone and minor lenses of limestone and dolostone, culminating at the top with pelites and dolostones containing Conophyton metulum Kirichenko stromatolites (Cloud and Dardenne 1973). In more detail it comprises the following, from the base (after Campos et al., 2013):
• São Miguel Conglomerate - the basal unit, with a maximum thickness of 60 m, which is a paraconglomerate containing pebbles and subangular blocks of metasiltite, quartz, quartzite and fine grey marble, set in a silty clay-carbonate matrix.
• Unit R1 - which is up to 70 m thick and occurs concordantly above the São Miguel conglomerate. It comprises a succession of marly bands, whith clayey meta-siltite at the base, grading to a meta-rhythmite with thin intercalations of fine- to medium-grained quartzite, generally feldspathic. Shrinkage cracks and salt cube pseudomorphs are common near the base of the unit.
• Unit Q1 - up to 80 m thick, comprising fine to medium grained, white, well stratified quartzite, occurring as 30 to 40 cm thick beds with rare intercalations of silty-clayey horizons at the top and frequent tabular crossed strata.
• Unit R2 - up to 150 m thick, marking an abrupt change to a lithofacies characterised by centimetric bands of fine pink quartzites, interspersed with meta-siltites and millimetric lenses of whitish mudstones, with wave truncated cross-laminations and common fluidisation structures.
• Unit Q2 - up to as much as 150 m thick, comprising decimetric to metric layers of medium to coarse-grained yellow-ochre quartzite, with fine feldspathic conglomeratic beds common towards the top containing subangular to rounded granules and pebbles. Turned tabular and herringbone cross bedding are common.
• Unit S - which can be as thick as 500 m or more and is very variable. It is subdivided into five lithofacies, each comprising a set of homogeneous greenish meta-siltite bands that may contain sandy intercalations to form meta-rhythmites, or rare limestone and dolostone lenses.
• Unit A - with a thickness that is difficult to measure due to intense folding, but is estimated at ~70 m thick. It has a transitional contact with the previous unit to a greenish grey homogeneous slate that weathers to a red colouration. Two penetrative foliations produce a slatey cleavage.
• Unit R3 - which has a total thickness of as much as 90 m. It is a sandy meta-rhythmite with characteristic intercalations of decimetric to metric bands of quartzite, pelitic meta-siltite and slate which may form up to 10 m thick local packages that stand out from the rhythmic sections.
• Unit Q3 - with a maximum thickness of 100 m in the Distrito Federal. It is composed of white, fine, highly silicified quartzites which contain abundant channeled and herringbone cross-bedding.
• Unit R4 - which ranges from 100 to 150 m in thickness. A clayey meta-rhythmite, composed of silty and clayey intercalations and thin, fine, pink to reddish quartzites. The sandy sections contain cross-laminations, wave-truncated and hummocky laminations.
• Unit PC - that varies from 120 to 150 m in thickness. A dominantly pelitic unit with grey slates and clayey metasiltites with associated fine marble lenses that may contain algal structures, including columnar and conical stromatolites. Dark, decimetric to metric scale, lenticular to tabular beds of conglomeratic quartzites are common.
The basal São Miguel Conglomerate represents an early high energy stage of the Paranoá basin, overlain by rhythmites with mudcracks and evaporite layers, reflecting a tidal environment. These are followed by marine rhythmites and quartzites deposited in a platformal environment dominated by tidal currents. The upper sections of the Paranoá Group have features suggesting more varied settings, reflecting sea level fluctuations due to transgressive-regressive cycles, with deeper water pelites alternating with tidal rhythmites and quartzites, storm rhythmites, limestones and stromatolitic dolomites. Arkoses and quartzites in the upper part of the sequence are interpreted to be chemically similar to passive margin clastic sediments (Pimentel, 2016; Guimaráes 1997). Deposition appears to have commenced in a rift basin developed on a passive cratonic margin grading to epicontinental platform marine conditions as a passive margin (Martins-Ferreira et al., 2018).
The stromatolites observed within the upper units are consistent with deposition between 1.3 and 1.0 Ga in the Mesoproterozoic (Dardenne et al., 1972; Cloud and Dardenne 1973, Dardenne 1979, Matteini et al., 2012). Sm/Nd isotopic information (Santos et al., 2000, 2004; Pimentel et al., 2001) indicate that the model ages for the different units of the group vary between 1.81 and 2.27 Ga, indicating the source of detritus is Palaeoproterozoic. U-Pb and Hf isotopic studies on detrital zircons (Matteini et al., 2012) concluded the Paranoá Group has a minimum age of deposition of 1042 Ma, based on diagenetic overgrowth of xenotime on detrital zircon, and a maximum age of 1542 Ma as a function of population. Based on additional dating of detrital zircons, Pimentel, 2016 concluded deposition was between ~1170 and 950 Ma (after Guimarães 1997; Pimentel et al., 2001; Matteini et al., 2012).
The Paranoá Group is found on the northwestern margin of the Brasilia Fold Belt, structurally overlain to the NW by older rocks of the Goiá Massif and is, in turn, thrust over the younger Bambuí Group shelf carbonates to the east. The sedimentary rocks were only affected by low-grade metamorphism, and deformation resulted in the formation of monoclines, with fold interference producing domes and structural basins (Campos et al., 2013).

Canastra Group - is variously interpreted to comprises a rift basin to passive margin platformal association as described above for the Paranoá Group. It comprises an association of psammitic and pelitic meta-sedimentary rocks, with some carbonatic intercalations and was sourced from the Archaean and Palaeoproterozoic São Francisco Craton basement and Mesoproterozoic cover units (Carvalho, 2019). It is subdivided into three formations from the base, (Dardenne, 2000) as follows:
• Serra do Landim Formation, the basal unit, which comprises greenish, chlorite-rich, laminated calc-phyllites with intercalations of light grey calc-schists. This formation has previously been interpreted to be the uppermost unit of the Vazante Group (Madalosso and Valle 1978, Madalosso 1980).
• Paracatu Formation, a thick succession of pyrite-bearing black carbonaceous to graphitic phyllites with interbedded layers and lenses of impure quartz sandstones to quartzite. It has been sub-divided into two members (Freitas-Silva and Dardenne, 1994), i). the lower Morro do Ouro Member, which is an ~100 m thick layer of pyrite-bearing black carbonaceous phyllite with relatively continuous thin quartzite interbeds, and ii). the overlying Serra da Anta Member, composed of sericitic phyllite with thin quartzite interbeds. The quartzite intercalations in both are fine-grained. The Morro do Ouro Member hosts the major Morro do Ouro gold deposit at Paracatu.
• Chapada dos Pilões Formation is divided into the: i). lower Serra da Urucânia Member which is composed of turbiditic intercalations of quartzite and phyllite; and the ii). overlying Serra da Batalha Member shallow platformal quartzite.
The Paracatu and the Chapada dos Pilões formations are interpreted to represent a coarsening-upward sequence formed by a regressive megacycle. This is composed of deep water sediments, grading into turbidites deposited on a continental slope by gravitational currents, passing up into platformal deposits in the Chapada dos Pilões Formation where hummocky structures and cross stratification, indicate sediment transport from east to west. The Canastra Group is considered to be the lateral equivalent of the Paranoá Group which it structurally underlies to the NW, separated by a NE-SW thrust near Brasilia (Dardenne 2000). Sedimentation of the Canastra Group is constrained by the youngest U-Pb ages of detrital zircons at 1.03 Ga (Rodrigues et al., 2010) and by a Re-Os age of 1002 45 Ma, from the basal Paracatu Formation (Bertoni et al., 2014). It forms a NW-SE aligned belt up to 100 km in width that have been mostly metamorphosed to greenschist facies but locally up to the garnet zone. It becomes progressively more heavily metamorphosed to the SE, where it passes into the interpreted equivalent Andrelândia Group (see below) which is at amphibolite to granulite facies. To the east it has been thrust over the laterally equivalent carbonates of the Vazante Group and the younger Bambuí Group. To the west it is overthrust by the temporally equivalent Araxá and Ibiá groups. The stratigraphic relationships between the Canastra and surrounding groups are not clear due to the intense tectonic imbrication.

Vazante Group - a pelitic-dolomitic shallow marine platformal sequence that forms an ~300 km long belt, structurally overlying the younger Bambuí Group to the east, and overlain across an east-vergent thrust by the Canastra and Ibiá groups to the west. The sequence is interpreted to have been deposited in the sag phase of a cratonic margin rift basin, grading to a passive margin. As defined by Dardenne (2000), it is divided into the following succession, from the base:
• Santo Antônio do Bonito Formation - white quartzite that is locally conglomeratic, interlayered with slaty horizons and restricted diamictite horizons, with local phosphorite occurrences as at Coromandel in Minas Gerais.
• Rocinha Formation - rhythmic sandy and pelitic rocks, including dark-grey carbonatic slates with pyrite and thin phosphatic laminations. The unit contains Conophyton Sp. stromatolites, interpreted by Dardenne (2000) as an imprecise indication of a Late Mesoproterozoic age, consistent with an Re-Os age of 1304 ±10 Ma (Bertoni et al., 2014). U-Pb ages of the youngest concordant detrital zircons of the formation are ~935 ±14 Ma (Rodrigues et al., 2012).
• Lagamar Formation - divided into the: i). lower Arrependido Member, a basal psammo-pelitic-carbonated alternation of conglomerates, quartzite and slates, overlain by the ii). Sumidouro Member stromatolitic bioherm dolomites with breccias and dark-grey limestones.
• Serra do Garrote Formation - dark-grey to greenish-grey slates, sometimes rhythmic and carbonaceous, with thin pyrite-rich interbedded quartzite.
• Serra do Poço Verde Formation - a dominantly dolomitic sequence with thin intercalated pelitic layers, subdivided into: i). Lower Morro do Pinheiro; ii). Upper Morro do Pinheiro; iii). Lower Pamplona; and iv). Medium Pamplona. These members are composed of differing combinations of dark to light-grey to pink dolomite, with cyanobacteria mats, columnar stromatolites, sometimes with Birdseye’s features, as well as breccias and interbedded pelitic rocks and greenish marls.
• Morro do Calcário Formation, (the Upper Pamplona Member of Rigobello et al., 1988) - a stromatolitic bioherm dolomite association with dolerite, breccias, and oolitic and oncolytic dolorudite facies.
• Serra da Lapa Formation - the uppermost unit of the Vazante Group, composed of grey carbonaceous phyllite and grey carbonatic-rich slate with lenses of dolomite, meta-siltstone and quartzite.
Detrital zircons younger than 0.93 Ga (U-Pb) have not been recorded in the Vazante Group, whilst TDM ages range between 1.41 and 2.76 Ga (Carvalho et al., 2018). The Vazante Group is interpreted to be stratigraphically equivalent to, or older than, the Canastra Group, deposited to the east of the latter in a craton margin rift basin to passive margin, closer to and with a greater input of detritus from the Tonian Intraplate Magmatism within the São Francisco Craton. The latter has TDM ages range between 0.93 and 1.63 Ga (Carvalho et al., 2018).
Dolomite of the Vazante Group host the Vazante and Morro Agudo zinc deposits. The Vazante mineralisation is tectonic controlled by a SE-dipping normal fault within dolomitic strata, between the lower Serra do Pamplona and upper Morro do Pinheiro members, of the Serra do Poço Verde Formation (Dardenne 2000, Monteiro et al., 2006, 2007), whilst the Morro Agudo deposits are hosted by fore-reef facies of dolomitic rocks from the Morro do Calcário Formation (Dardenne 1978).

Serra da Mesa Group, which is restricted to the Campinorte Terrane of the Goiás Massif where it comprises a metasedimentary succession that almost entirely and unconformably covers the the Palaeoproterozoic Campinorte Sequence, as described in the Campinorte Terrane section above. This group is variously recorded as being Meso-, Meso- to Neo- and Neoproterozoic, and has been described as a possible equivalent of the Brasilia Belt sequence in the Goiás Massif. However, sources quoted by Slezak (2012) suggest it spans the interval from 1600 to 1470 Ma in the Mesoproterozoic and is composed of quartzites, micaceous schists and marbles (Dardenne, 2000; Fuck and Marini, 1981; Marini et al., 1984). It has been overthrust from the west by the Neoproterozoic Mara Rosa Arc of the Goiás Magmatic Arc, where imbrication and consequent crustal thickening has metamorphosed it to amphibolite facies. It is interpreted to be a possible temporal equivalent of the stratigraphically upper units of the Araí Group to the north in the Gaoiá Massif and the Espinhaço Supergroup of the São Francisco Craton, but possibly older than the Paranoá-Canastra-Vazante groups.

Deposition within the Paranoá Basin section of the Brasilia Fold Belt involved the Paranoá, Canastra and Vazante groups, and sections of the Andrelândia Group to the south. It appears to have commenced as a cratonic margin rift basin towards the western edge of the São Francisco palaeocontinent. This rifting may represent reactivation and eastward migration of the older, initially Statherian Palaeo- to Mesoproterozoic Araí Rift Basin that hosts the Araí and equivalent Serra da Mesa groups on the Goiás Massif. Similar rift basin development hosts the Palaeo- to Neoproterozoic Espinhaço Supergroup to the east on the SãO Francisco Craton (as described previously). Deposition commenced with an initial tectonic event producing high energy sedimentation, followed by alternating tidal to deeper water settings, progressing to the latter being dominant, and then to late carbonates. The extensive lateral continuity and relatively constant thickness of facies are taken to indicate initial rift subsidence rapidly progressed to a flexural sag phase (Martins-Ferreira et al., 2018). The main stratigraphic characteristics, tectonic location and basement architecture are consistent with the cratonic margin rift basin being either connected to a passive margin shelf basin during sea level highs, or its subsequent evolution to a passive margin (Martins-Ferreira et al., 2018). However, by the mid Neoproterozoic the western margin of the fold belt was a passive margin during deposition of the more outboard Ibiá and Araxá groups. During this period, the oceanic crust west of the cratonic margin was being consumed by the ENE to NE-vergent leading edge of the Paranápanema Block on which the intraoceanic Arenópolis Arc was being formed.

Andrelândia Group - is mapped in the southwestern extremity of the Brasília Orogen, where it is affected by the complex superposition of the collision between the São Francisco palaeocontinent and the Arenópolis Arc from the SW at ~750 Ma, and the combined Ribeira Belt Inner and Outer arcs from the SSE at ~650 Ma (Fig. 1). For details of timing and results of these collisions, the concomitant imbrication and later tectonic relaxation and extension see the Arenópolis Arc and Ribeira Belt descriptions. Both collisions resulted in an extended period of imbrication as the advancing arcs were thrust over the passive margin sequences of the Brasilia Belt deposited on the margin of the São Francisco palaeocontinent, which in the south, was the Andrelândia Group. This imbrication and crustal thickening led to high temperature and pressure metamorphism. Consequently, the Andrelândia Group is more intensely metamorphosed, compared to the interpreted equivalents and was deformed into thrust sheets and nappes. The Paranoá-Canastra-Vazante and Araxá groups have a lateral gradational boundary with the Andrelândia Group to its north. The group is composed of paragneisses, quartzites, schists and mafic/ultramafic rocks that were metamorphosed to amphibolite and granulite facies.
In more detail, this Neoproterozoic, largely metasedimentary, sequence is divided into two main sequences separated by a regional unconformity (Paciullo et al., 2000), subdivided into the:
• Carrancas Sequence, made up of the i). São Vicente Unit - banded paragneiss with amphibolite; ii). São Tomé das Letras Unit - quartzite with phyllite/schist intercalations, succeeded by more quartzites; iii). Campestre Unit - graphitic phyllites/schists intercalated with quartzites, that grade in more distal parts to the iv). Arantina Unit, which is composed of schists that are rich in garnet, plagioclase, kyanite and/or sillimanite, and occasionally rutile.
The sequence contains intercalations of gneiss, amphibolite, quartz schist, quartzite, calc-silicate rocks, quartz-garnet rocks and mafic/ultramafic lenses, and is interpreted to represent the most distal, deep oceanic lithofacies of the Andrelândia Group (Ribeiro et al., 1995; Paciullo et al., 2000: Coelho et al., 2017).
Maximum sedimentation ages of 0.92 and 0.98 Ga have been returned for the São Tomé das Letras and Campestre units (Westin et al., 2019; and Marimon et al., 2020), and 0.76 Ga for the Arantina Unit (Frugis and Campos Neto, 2018).
• Serra do Turvo Sequence, which Paciullo et al. (2000, 2003) interpreted to have a glacial origin, comprises the Santo Antônio Unit that is composed of homogeneous biotite schist with youngest detrital zircon ages of 670 Ma, possibly sourced from a magmatic arc. It rests unconformably on both basement and the Carrancas Sequence in different areas (Frugis and Campos Neto, 2018).
This southern section of the Brasília Orogen is composed of an east-vergent nappe stack, interpreted to have been generated by the collision between the Paranápanema and São Francisco palaeocontinents (Campos Neto and Caby, 1999, 2000; Trouw et al., 2000; Campos Neto et al., 2004), between 630 and 600 Ma (Valeriano et al., 2004, 2008; Campos Neto et al., 2007, 2010, 2011; Trouw et al., 2013; Reno et al., 2009; Rocha et al., 2017). The lower nappes of the stack, comprise the Lower or Carrancas Nappe System, which lies below the Andrelândia Nappe System. Both are composed of rocks of the Andrelândia Group (Ribeiro et al., 1995; Paciullo et al., 2000, Belém et al., 2011; Westin and Campos Neto, 2013; Westin et al., 2019 ). However, whilst the Carrancas Nappe System is composed of sedimentary rocks of the Carrancas Sequence deposited on the western passive margin of the São Francisco palaeocontinent (Westin et al., 2019; Marimon et al., 2020), the Andrelândia Nappe System (Fig. 1; Campos Neto et al., 2004, 2007), are interpreted as either i). derived from a fore arc basin, related to the upper Paranápanema plate (Campos Neto et al., 2010, 2011; Westin et al., 2016, 2019; Frugis and Campos Neto, 2018); or ii). distal facies of the passive margin sequence of the lower plate São Francisco palaeocontinent (Ribeiro et al., 1995; Paciullo et al., 2000; Trouw et al., 2000, 2013; Coelho et al., 2017). The Andrelândia Nappe System is mainly composed of a pile of deformed meta-sedimentary rocks, with slices of Palaeoproterozoic basement, including retrogressed eclogitic lenses at the base of several nappes within the system (Trouw et al., 2000). It occurs as an inverted metamorphic stack, in which medium- to high-P granulite facies rocks are thrust over lower grade amphibolite facies rocks (Trouw et al., 2000; Paciullo et al., 2003; Campos Neto et al., 2010, 2011). Zircon grains from the retro-eclogite have metamorphic rims grown in high-P conditions of 12 to 16 Kbar and ∼700 to 800°C are dated at 625±6 Ma (SHRIMPU-Pb zircon), interpreted to be the age of 'continental subduction' of the São Francisco plate below the Paranápanema palaeocontinent (Coelho et al., 2017).
Nappe emplacement associated with this collision is interpreted to have been accompanied by melting in the middle of the Andrelândia Nappe System, evidenced by a garnet-muscovite-staurolite-kyanite schist with a leucosome parallel to the main foliation dated at 618 ±5 Ma (SHRIMPU-Pb zircon). A retrograde re-equilibrium event at pressures of 4 to 7 Kbar and ∼500 to 700°C is attributed to a second lower pressure heat pulse that occurred at 586 ±9 Ma, marked by an anatectic tourmaline-garnet-muscovite bearing S-type granite. The latter is part of a NE-SW belt of 605 and 563 Ma granites that overlap both the Southern Brasília and Central Ribeira orogens, and is interpreted to be related to the collisional front of the latter orogen and the consolidation of the two by ~580 Ma.
The uppermost Socorro-Guaxupé Nappe (Fig. 2), is interpreted to represent the active margin of the Paranápanema palaeocontinent (Campos Neto and Caby, 1999, 2000; Campos Neto et al., 2004, 2010; Trouw et al., 2000, 2013; Valeriano et al., 2004, 2008; Vinagre et al., 2014). As such the suture between the Paranápanema and São Francisco plates is at, or below, the base of the Socorro-Guaxupé Nappe, and that nappe represents a southern continuation of the Arenópolis Arc (e.g., Westin et al., 2019). This upper nappe is a thick tectonic slab, mainly composed of migmatitic orthogneiss formed from the lower and middle section of a continental magmatic arc (Campos Neto c, 2004; Trouw et al., 2013; Vinagreet al., 2014). It is segmented into the northern Guaxupé and southern Socorro lobes, separated by a large antiformal structure that is bounded by high angle shear zones. Geochemical and isotopic data from the abundant, deformed, 680 to 630 Ma plutonic bodies are consistent with a continental arc (Ebert et al., 1996; Vinagre et al., 2014, Vinagre, 2014). The Socorro-Guaxupé Nappe rocks grade from granulite facies at the base, to medium pressure amphibolite facies towards the top. The basal granulites were formed at 870 to 750°C and 14.5 to 11.5 Kbar (Del Lama et al., 2000), and are dated at 617 ±1.3 Ma (Campos Neto et al., 2010). It is interpreted as the remnant root of a magmatic arc (the Socorro-Guaxupé Arc) on the active margin of the Paranápanema Paleocontinent (Campos Neto and Caby, 1999, Campos Neto and Caby, 2000, Janasi, 1999, Janasi, 2002, Trouw et al., 2000, Vinagre et al., 2014).
The current lateral metamorphic facies distribution within the southern Brasília Belt varies from greenschist facies along the margin of the São Francisco palaeocontinent, to high pressure granulite facies in the Andrelândia Nappe System along the suture with the Ribeira Belt.
Within the Andrelândia Nappe System, below the Socorro-Guaxupé Nappe, the Neoproterozoic Andrelândia Group rocks are interleaved with slices of Archaean and Palaeoproterozoic sedimentary rocks (Cioffi et al., 2016). These older sedimentary rocks are referred to as the Itapira Group, and occur as narrow strips in a large antiform, limited by transcurrent shear zones. It consists of feldspathic quartzite, quartz-paragneiss, feldspathic schist, marble, calc-silicate rock, quartz garnet rock, gondite and graphitic schist and is intercalated with centimetre to metre scale elongated bodies of 2.2 to 2.1 Ga mafic and ultramafic rocks (Lazarini, 2008; Westin et al., 2016). A minimum depositional age is indicated by a 1726 ±21 Ma granite intrusion, the Taguar Gneiss (Westin et al., 2016).
Basement is composed of 3 to 2.76 Ga (U-Pb zircon) migmatitic orthogneisses and TTG of the Amparo Complex (Ebert, 1968; Zanardo, 1987; Fetter et al., 2001; Cioffi et al., 2016), and 2.15 to 2.08 Ga (crystallisation ages) tonalitic to granodioritic orthogneisses of the Pouso Alegre Complex (Cioffi et al., 2016; Peternel et al., 2005), interpreted to belong to the São Francisco palaeocontinent (Ávila et al., 2010, 2014; Cioffi et al., 2016; Westin et al., 2016). These most likely equate with the Mesoarchaean and Palaeoproterozoic rocks of the Quadrilátero Ferrífero Block described in the São Francisco Craton section above.
This section is largely derived from Fontainha et al. (2021).

Andrelândia Group References
Fontainha, M.V.F. Trouw, R.A.J., Dantas, E.L., Polo, H.J.O., Furtado, P.C., Marimon, R.S., Telles, R.C.M. and Peternel, R., 2021 - Provenance and tectonic evolution of the Andrelandia Group in the region between the Socorro and Guaxupe nappes, Southern Brasília and Ribeira orogens, Brazil; Journal of South American Earth Sciences, v.109, 26p. doi.org/10.1016/j.jsames.2020.103060.
Coelho, M.B., Trouw, R.A.J., Ganade, C.E., Vinagre, R., Mendes, J.C. and Sato, K., 2017 - Constraining timing and P-T conditions of continental collision and late overprinting in the Southern Brasília Orogen (SE-Brazil): U-Pb zircon ages and geothermobarometry of the Andrelândia; Precambrian Research, v.292, pp. 194-215. doi.org/10.1016/j.precamres.2017.02.001.
Seraine, M., Campos, J.E.G., Martins-Ferreira, M.A.C., Alvarenga, C.J.S., Chemale Jr. F., Angelo, T.V. and Spencer, C., 2021 - Multi-dimensional scaling of detrital zircon geochronology constrains basin evolution of the late Mesoproterozoic Paranoá Group, central Brazil; Precambrian Research, v.365, doi.org/10.1016/j.precamres.2021.106381.

While the Paranoá, Canastra and the Vazante groups have detrital zircon grains with ages older than ~900 Ma and are interpreted as representative of the continental rift to passive margin sequence deposited on the western edge of the São Francisco Craton, the Araxá and Ibiá groups have a much younger population of Neoproterozoic zircon grains, as young as 650 Ma. The Bambuí Group, exposed in the easternmost part of the belt and covering large areas of the São Francisco Craton also has young zircon grains (Pimentel et al., 2011; Pimentel, 2016).

Ibiá Group - unconformably overlies the Canastra Group to the east, and structurally overlies the Araxá Group to the west. It is composed of two units, namely:
• Cubatão Formation, comprising an up to 100 m thick meta-paraconglomerate/diamictite occurring at the base of the sequence. It overlies a sharp contact that represents an erosive unconformity with the Canastra Group. It occurs as discontinuous lenses that are up to 100 m thick and includes intercalations of orange phyllite, quartzite and grey micaceous quartzite. Clasts are mainly of quartzites, resembling those of the Canastra Group, and vein quartz, set in an areno-micaceous matrix. Although it largely only occurs as discontinuous lenses, along its northeastern margin it is thicker and has a greater lateral continuity (Campos Neto, 1984, Pereira et al., 1994). Where present, it is always found above micaceous quartzite and phyllite of the Canastra Group but is thinner to absent where the succeeding Rio Verde Formation schist pile is thickest. It has been correlated with the Neoproterozoic Jequitai Formation diamictites found over the São Francisco Craton and in the Araçuaí Belt to the east.
• Rio Verde Formation, composed of chlorite-muscovite schist, calc-schists and calc-phyllites with fine layers of quartzite, representing metamorphosed deep water facies sedimentary rocks that overlie both the Cubatão Formation and Canastra Group. The dominant age of detrital zircons from this unit is <1000 Ma, with concentration peaking at 850, 740 and 665 Ma, whilst the mean age of the youngest is ~639 Ma (U-Pb; Rodrigues et al., 2010, Pimentel et al., 2011). The youngest zircon population shows poorly rounded to euhedral crystals, some of which are interpreted to be of volcanic origin. Lithogeochemical data, together with the mineralogical composition, have been interpreted to suggest provenance from intermediate to mafic igneous sources. These observations have led to the conclusion that the provenance of the Rio Verde Formation protoliths was mainly from 'magmatic arcs of the Brasília Belt' (Dias et al., 2011), specifically the Neoproterozoic Arenópolis section of the Goiás Magmatic Arc. Some contribution from the São Francisco Craton and/or from the western basement of the Brasília Belt is also inferred (Rodrigues et al., 2010). The Rio Verde Formation is considered to be equivalent to the metasedimentary rocks of the Araxá Group (Pimentel, 2016).

Ibiá Group References
Dias, P.H.A., Noce, C.M., Pedrosa-Soares, A.C., Seer, H.J., Dussin, I.A., Valeriano, C.M. and Kuchenbecker, M., 2011 - O Grupo Ibiá (Faixa Brasília Meridional): evidências isotópicas Sm-Nd e U-Pb de bacia colisional tipo flysch; Geonomos, v.19, pp. 90-99.

Araxá Group - forms an ~700 km long, NNW trending belt, that separates the Goiás Magmatic Arc to the SW and NW, from the passive margin meta-sedimentary units of the Paranoá Basin to the east. The latter was developed on the western margin of the São Francisco Craton/palaeocontinent. The intervening Ibiá Group thrust sheet represents a transitional sequence intermediate between the passive margin and the Araxá Group.
The internal stratigraphy of the Araxá Group is poorly known due to intense deformation with development of low angle, east-vergent thrust sheets internal and marginal to its exposure. It is mainly composed of micaceous quartzite and mica-schists including calc-, chlorite-muscovite-, biotite-garnet-, staurolite- and feldspar-schists, with a few paragneiss and marble intercalations. These schists are interpreted to represent marine deep-water metasedimentary protoliths with associated chert layers, the latter now fine orthoquartzites. Dominantly metamafic volcanic rocks are widespread in many areas, occurring as fine and coarse amphibolites, with rare ultramafic rocks, and are transitional to the pelitic metasedimentary rocks. Both volcanic and sedimentary rocks are metamorphosed to amphibolite facies conditions, and are intruded by granitoid rocks. The amphibolites represent gabbroic and basaltic protoliths. Amphibolites near Goiânia have been dated at ~0.8 Ga (SHRIMP U-Pb zircon; Piuzana et al., 2003). The basalts are high FeO tholeiites with REE signatures that resemble E-MORB (Seer and Moraes, 2000). The amphibolites have been interpreted as slices of ocean floor tectonically emplaced within the Araxá metasedimentary rocks (Pimentel, 2016). They include a large number of small lenses of serpentinite, amphibolite and talc schist, with podiform chromite deposits, representing a long, roughly north-south ophiolitic mélange (Strieder and Nilson 1992). In the eastern half of the Araxá Group belt, a north-south oriented, narrow strip of rocks, bounded by shallowly west dipping thrusts, has been differentiated on structural grounds. This is the Veríssimo Sequence, which is composed of garnet-bearing chlorite schists, sericite phyllites with quartzite lenses, carbonaceous phyllites, muscovite-schists intercalated with chlorite-schist and associated amphibolites, quartzites and quartz-schists, and felsic metavolcanic rocks that are characterised by blue quartz (Dardenneet al., 1994). These rocks are otherwise indistinguishable from the rest of the Araxá Group.
The belt defined by the Araxá Group encloses a 10 to 75 km wide by near 600 km long thrust bound core of orthogneisses and granulites. In the centre and south, this core has been subdivided into four main suites, not all of which are present over the whole length of this core. Each is also separated by ENE vergent thrusts (e.g., Piauilino et al., 2021). These suites and their extensions and variations are (after Klein, 2008) the:
• Nova Aurora Orthogneiss - which is found on the western margin of the core and is of Mesoproterozoic age, dated at 1219 ±13 Ma. It has Nd model ages of between 1413 and 2624 Ma, which with other data is interpreted to suggest mixed juvenile and older heterogeneous sources. It may well represent basement to the Arraxá Group and either an extensions of the Goiás Massif, or an exotic microcontinental fragment.
• Goiandira Orthogneiss - found immediately to the east, and has a Neoproterozoic ages of between 717 ±39 and 634±9 Ma and Nd model ages range between 1371 and 2541 Ma.
• Ipameri Orthogneiss - on the eastern margin of the core. It returned U-Pb zircon ages from two orthogneiss samples of 796 ±64 and 771 ±13 Ma, and Nd model ages between 1913 and 2057 Ma, with one lower value of 1284 Ma.
The Goiandira and Ipameri orthogneiss domains are related to continental magmatism on the margin of the São Francisco palaeocontinent, and continue northward as the broader Anápolis-Itauçu granulite terrain. These rocks are interpreted to be related to an intracontinental extensional event between 800 and 720 Ma, evolving to oceanic crust with T-MORB to E-MORB affinities (Klein, 2008). Some other dioritic, tonalitic and granitic orthogneisses found locally across this core differ in character, in that they have a very high- to high-K and peraluminous affinity, and are probably of alkaline nature.
• Maratá Sequence, composed of fine-grained amphibolites and metagabbros interbedded with chemical meta-sediments (gondites) and felsic metavolcanic rocks (Lacerda Filho et al., 1995). These are stratigraphically overlain by schists after metapelites, metagraywackes, micaceous quartzites, and quartz schists (Dardenne et al., 1991). U-Pb on zircon grains indicated crystallisation at 794  ± 10  Ma (Pimentel et al., 1992) and 791  ±  8  Ma (Klein, 2008). These define an ~100 km long, narrow, 2 to 15 km wide, strip bounded by shallow thrusts and are highly deformed rocks that cuts obliquely across the main members of the orthogneiss core and into the Araxá Group. The western margin is occupied by an attenuated lense of strongly deformed granite.
In addition to the orthogneisses of the core, there are numerous granite plutons intruded into the both the metamorphic core and flanking Araxá Group meta-volcanosedimentary succession. These represent three Neoproterozoic granitic episodes, as follows:
i). an early 833 Ma event, interpreted to represent 'within-plate' magmatism which geochemical data suggest originated from mantle sources with only minor crustal contamination. This is exemplified by the Quebra Anzol Granite found in the south-eastern nose of the Araxá Nappe (Fig. 2; Seer and Moraes, 2000).
ii). a second episode at ~790 Ma, represented by the pre-collisional Monte Carmelo Granitic Complex which is intensely deformed, particularly along its borders, and is associated with a large volume of medium to coarse amphibolites of the Chapada das Perdizes Complex (Brod et al., 1991). It is located to the north of the Araxá Nappe and is the most extensive of the granitic masses, and was partially remobilised at ~630 Ma. Geochemical data indicate it varies from metaluminous to peraluminous, and suggest this granite originated from juvenile sources (Seer and Moraes, 2000).
iii). a final granitic episode between 642 and 630 Ma, producing peraluminous granites with muscovite, garnet and tourmaline, in the Serra Velha, Tamanduá, Pirapetinga, Galheirinho, Perdizes, Estrela do Sul and Cascalho Rico granites, distributed over an interval of ~200 km from the southern tip of the Araxá Nappe and to the NNW (Seer and Moraes, 2000).
The Arraxá Group is interpreted to represent deep ocean deposition, distal to the margin of the São Francisco Craton, but more proximal to the Arenópolis Arc of the Goiás Magmatic Arc. As such, its southwestern margin likely corresponded to an accretionary wedge, grading NE into a fore-arc basin to the the Arenópolis Arc subduction zone, and has been thrust east ahead of the arc to structurally overlie the intermediate Ibiá Group and the passive margin sequences of the Vazante-Canastra-Paranoá groups (e.g., Carvalho et al., 2019).
On the basis of a detailed study of the amphibolite rocks and enclosing metasedimentary sequences in the southeastern half of the Araxá Group belt, Piauilino et al. (2021), differentiated three main mafic magmatic pulses, and interpreted the following series of events:
• The Veríssimo Sequence, was deposited in an extensional setting at ~0.98 Ga, where crustal attenuation promoted mantle upwelling and the concomitant emplacement of both E-MORB- and OIB-like basalts. Sedimentation was characterised as a volcano-sedimentary sequence, with detritus derived from the western margin of the Sõo Francisco Craton, and a minor contribution of volcaniclastic material eroded from the Nova Aurora Domain.
• Mafic magmatism in the stratigraphically overlying Araxá Group rocks has the characteristics of forearc E-MORB basalt dated at ~870  Ma age and OIB-like basalts from ~820  Ma, probably generated in a continued extension setting.
• Gabbroic OIB-like rocks were intruded into the Araxá Group at 650  Ma, coeval with imbrication and overthrusting of the metamorphic core of the Anápolis-Itauçu Complex. This mafic magmatism was related to the final stages of a collisional event in a continental environment and closure of the Neoproterozoic ocean.

Araxá Group References
Basei, M.A.S., Brito Neves, B.B., Siga Junior, O., Babinski, M., Pimentel, M.M., Celso, C., Tassinari, G., Hollanda, M.H.B., Nutman, A. and Cordani, U.G., 2010 - Contribution of SHRIMP U-Pb zircon geochronology to unravelling the evolution of Brazilian Neoproterozoic fold belts; Precambrian Research, v.183, pp. 112-144. https://www.sciencedirect.com/ science/article/pii/S0301926810001956.
Klein, P.B.W., 2008 - Geoquímica de rocha total, geocronologia de u-pb e geologia isotópica de sm-nd das rochas ortognáissicas e unidades litológicas associadas da região ipameri - Catalão (Goiás); Tese (Doutorado em Geologia)-Universidade de Brasília, Brasília, 2008.
Piauilino, P.F., Hauser, N. and Dantas, E.L., 2021 - From passive margin to continental collision: Geochemical and isotopic constraints for E-MORB and OIB-like magmatism during the neoproterozoic evolution of the southeast Brasília Belt; Precambrian Research, v.359, doi.org/10.1016/j.precamres.2019.105345.
Pimentel, M.M., 2016 - The tectonic evolution of the Neoproterozoic Brasília Belt, central Brazil: a geochronological and isotopic approach; Brazilian Journal of Geology, v.46 (Suppl. 1), pp. 67-82.
Seer, H.J. and Dardenne, M.A., 2000 - Tectonostratigraphic terrane analysis on neoproterozoic times: the case study of Araxá Synform, Minas Gerais State, Brazil: implications to the final collage of the Gondwanaland; Revista Brasileira de Geociências, v.30, pp. 78-81.
Seer, H.J. and Moraes, L.C., 2013 - Within plate, arc, and collisional Neoproterozoic granitic magmatism in the Araxá Group, Southern Brasília belt, Minas Gerais, Brazil; Brazilian Journal of Geology, v.43, pp. 333-354.
Slezak, P.R., 2012 - Geology, mineralogy, and geochemistry of the Vazante northern extension zinc silicate deposit, Minas Gerais, Brazil; A thesis submitted to the Department of Geological Sciences and Geological Engineering; SA thesis submitted in conformity with the requirements for the degree of Master of Science, Queen’s University, Kingston, Ontario, Canada, 497p.

Bambuí Group, which comprises a thick Neoproterozoic succession of carbonate and siliciclastic units, generated by three transgressive-regressive cycles in a shallow epicontinental sea. It was largely deposited over the São Francisco Craton, where it is a member of the São Francisco Supergroup, but also laps onto the Paranoá Basin passive margin/platform of the Brasília Belt to the west. The sequence is described in more detail in the Neoproterozoic section of the São Francisco Craton section above. Its western margin is mostly marked by the east-vergent Rio Paraná thrust zone (Reis et al., 2020) that juxtaposes it below rocks of the older Paranoá-Canastra-Vazante groups. This thrust is not identified in geophysical data at depths of >8 km, and it is interpreted to represent thin-skinned tectonics associated with the Brasiliano Orogeny (Reis et al., 2020). However, where the stratigraphic contact is exposed, its basal unit, the Jequitaí Formation glacial diamictite, sits unconformably on the Paranoá-Canastra-Vazante groups sequence. This glacial event was followed by a marine environment and the onset of pelitic-carbonatic sedimentary deposition. Each of the three regressive megacycles began with a rapid regional marine transgression, associated with a sudden subsidence of the basin, as evidenced by deep pelitic marine facies, passing to shallow-platform and then to tidal to supratidal rocks. Sr and Pb isotopic data reported by Parenti-Couto et al. (1981) suggested depositional ages of ~600 Ma, whilst Rb-Sr and K-Ar data on shales reported by Thomaz Filho et al. (1998) gave ages of between ~640 Ma for the basal Sete Lagoas Formation and 540 Ma for the Três Marias Formation at the top of the succession. Cap dolostones at the base of the Sete Lagoas Formation have been dated at ~740 Ma (Pb-Pb isochron; Babinski et al. 2007). This data, associated with C and Sr isotopic values for the carbonates, support a Sturtian age for the Jequitaí glaciation. However, detrital zircon dating by Rodrigues (2008) and Pimentel et al. (2011), for the basal Sete Lagoas, Serra de Santa Helena and Serra da Saudade formations, revealed significant numbers of late Neoproterozoic zircons, dated at ~600 Ma and even a few grains being as young as 550 Ma. This suggests a very late Neoproterozoic or even early Cambrian depositional age. This is supported by the discovery of Ediacaran fauna in carbonates of the Sete Lagoas Formation (Warren et al. 2014).

Brasilia Belt References
Campos J.E.G., Dardenne, M.A., Freitas-Silva, F.H. and Martins-Ferreira, M.A.C., 2013 - Geologia do Grupo Paranoá na porção externa da Faixa Brasília; Brazilian Journal of Geology São Paulo, v.43/3, pp. 461-476.
Chaves, A.O. and Correia Neves, J.M., 2005 - Late Paleoproterozoic Large Igneous Provinces from central and southeastern Brazil; http://www.largeigneousprovinces.org/05feb (LIP 1.72 dyke swarm Brasilia and Sao Francisco Craton).
Kuchenbecker, M., Pedrosa-Soares, A.C., Babinski, M., Reis, H.L.S., Atman, D. and da Costa, R.D., 2020 - Towards an integrated tectonic model for the interaction between the Bambuí basin and the adjoining orogenic belts: Evidences from the detrital zircon record of syn-orogenic units; Journal of South American Earth Sciences, v.104, doi.org/10.1016/j.jsames.2020.102831.
Kuster, K., Ribeiro, A., Trouw, R.A.J., Dussin, I and Marimon, R.S., 2020 -The Neoproterozoic Andrelândia group: Evolution from an intraplate continental margin to an early collisional basin south of the São francisco craton, Brazil; Journal of South American Earth Sciences, v.102, doi.org/10.1016/j.jsames.2020.102666.
Martins-Ferreira, M.A.C., Campos, J.E.G. and Von Huelsen, M.G., 2018 - Tectonic evolution of the Paranoá basin: New evidence from gravimetric and stratigraphic data; Tectonophysics, v.734-735, pp. 44-58. doi.org/10.1016/j.tecto.2018.04.004.
Pimentel, M.M., Rodrigues, J.B., Della Giustina, M.E.S., Junges, S., Matteini, M. and Armstrong, R., 2011 - The tectonic evolution of the Neoproterozoic Brasília Belt, central Brazil, based on SHRIMP and LA-ICPMS U-Pb sedimentary provenance data: A review; Journal of South American Earth Sciences, v.31, pp. 345-357.
Pimentel, M.M., 2016 - The tectonic evolution of the Neoproterozoic Brasília Belt, central Brazil: a geochronological and isotopic approach; Brazilian Journal of Geology, v.46, pp. 67-82.
Reis, L.K.O.D., Vidotti, R.M., Cordeiro, P. and de Oliveira, C.G., 2020 - The western São Francisco pericraton interpreted from crustal magnetic and gravity sources; Journal of South American Earth Sciences, v.103, doi.org/10.1016/j.jsames.2020.102716.
Reis, L.K.O.D., 2019 - Tectonic Framework of the Central Portion of the Brasília Belt; 16th International Congress of the Brazilian Geophysical Society held in Rio de Janeiro, Brazil, 19-22 August 2019.
Valeriano, C.M., Pimentel, M. M., Heilbron, M., Almeida, J.C.H. and Trouw, R.A.J., 2008 - Tectonic evolution of the Brasilia Belt, Central Brazil, and early assembly of Gondwana; in Pankhurst, R.J., Trouw, R.A.J., Brito Neves, B.B. and Wit, M.J. (Eds.), West Gondwana:Pre-Cenozoic Correlations Across the South Atlantic Region; Geological Society, London, Special Publications, v.294, pp. 197-210.
Westin, A., Neto, M.C.C., 2013 - Provenance and tectonic setting of the external nappe of the Southern Brasília Orogen; Journal of South American Earth Sciences, v.48, pp. 220-239. doi.org/10.1016/j.jsames.2013.08.006.
Westin, A., Neto, M.C.C., Cawood, P.A., Hawkesworth, C.J., Dhuime, B. and Delavault, H., 2019 - The Neoproterozoic southern passive margin of the São Francisco craton: Insights on the pre-amalgamation of West Gondwana from U-Pb and Hf-Nd isotopes; Precambrian Research, v.320, pp. 454-471. doi.org/10.1016/j.precamres.2018.11.018.

TRANSBRASILIANO LINEAMENT

The Transbrasiliano Lineament is a broad, up to 100 km wide, continental-scale discontinuity that separates the pre-Tonian Amazonian Craton domain to the west, including the Parnaíba Block and São Luis Craton to the north, from the series of cratonic fragments, magmatic arcs, allochthonous blocks and Neoproterozoic mobile belts that constitute the São Francisco/Brasiliano domain in the eastern portion of the South American Shield. It can be traced for more than 4000 km in South America, from the northeastern Brazilian continental shelf in Ceará, across the northern Borborema Province and the southeastern Parnaíba Basin, where it is entirely concealed by Phanerozoic sedimentary rocks, to emerge to the SW. There it separates the Goiás Massif from the Araguaia and Paraguaia fold belts, extending below the Paraná Basin to the northern boundary of the Patagonian Terrane. As such it separates two domains of markedly different geological, geotectonic and geochronological character. To the NE of Brazil, across the Atlantic Ocean and prior to the Cretaceous seperation of South America and Africa, it is interpreted to have continued in West Africa as the ~2000 km long Hoggar-Kandi Shear Zone.
The Transbrasiliano Lineament was originally formed during the final tectonic episode of the Brasiliano-Pan African Orogeny in the late Neoproterozoic, between 580 and 550 Ma (Marini et al., 1984; Cordani et al., 2010, 2013). It was initially the product of a Brasiliano-Pan African collision, that was subsequently translated into transcurrent kinematics. Locally, over the extent of the Goiás Massif, collision first involved the generally east-vergent overthrusting of the Mara Rosa Arc over the massif. The arc was developed on the leading edge of the Araguaia Belt, which was also the leading edge of the Amazonian plate. This initial collision and overthrusting was followed by coeval, sinistral, WNW vergent thrusting to the west of the lineament, producing a flower structure pattern with the two opposite thrust vergences. Much of the arc lies within the lineament. To the NE, both the Amazonian and São Francisco cratonic domains diverge, and the Mara Rosa Arc of the Goiás Magmatic Arc is interpreted to taper and lens-out beneath the Parnaíba Basin cover.
There is structural evidence of predominantly dextral displacement along the lineament during the late Neoproterozoic (Pimentel and Fuck, 1992; Arthaud, 2007; Dantas et al., 2007). Where it separates the Cuiabá Group of the Paraguaia Belt (see below) from the metavolcanic-sedimentary sequence of the western Arenópolis Arc, small elongated granite intrusions show pronounced subvertical mylonitic foliation, which crosscuts earlier ductile deformation, and lateral displacement of those granites by >8 km (Seer, 1985; Pimentel and Fuck, 1992). Three 20 to 30° directed Neoproterozoic deformations are evident in the same area, overprinted by a fourth orthogonal to the others.
The Transbrasiliano Lineament has also undergone at least three episodes of reactivation during the Phanerozoic. Cambrian-Ordovician and Silurian-Devonian reactivation produced small pull-apart basins, whilst a third episode accompanied the Cretaceous opening of the Atlantic Ocean. Dextral movement of ~100 km along the shear zones that define the lineament would be required to explain how the South American continent could have fitted tightly to the African continent before the breakup of Gondwana (e.g., Fairhead et al., 2007).

Transbrasiliano Lineament References
Brito Neves, B.B. and Fuck, R.A., 2014 - The basement of the South American platform: Half Laurentian(N-NW) + half Gondwanan (E-SE) domains; Precambrian Research, v.244, pp. 75-86.
Caxito, F.A., Santos, L.C.M.L., anade, C.E., Bendaoud, A., Fettous, E.-H. and Bouyo, M.H., 2020 - Toward an integrated model of geological evolution for NE Brazil-NW Africa: The Borborema Province and its connections to the Trans-Saharan (Benino-Nigerian and Tuareg shields) and Central African orogens; Brazilian Journal of Geology, 38p. doi: 10.1590/2317-4889202020190122.
Cordani, U.G., Pimentel, M.M., Araújo, C.E.G. and Fuck, R.A., 2013 - The signiicance of the Transbrasiliano-Kandi tectonic corridor for the amalgamation of West Gondwana; Brazilian Journal of Geology, São Paulo, v.43, pp. 583-597. doi:10.5327/Z2317-48892013000300012.
Curto, J.B., Vidotti, R.M., Fuck, R.A., Blakely, R.J., Alvarenga, C.J.S. and Dantas, E.L., 2014 - The tectonic evolution of the Transbrasiliano Lineament in northern Paraná Basin, Brazil, as inferred from aeromagnetic data; Journal of Geophysical Research: Solid Earth, v.119, pp. 1544-1562. doi:10.1002/2013JB010593.
Fairhead, J.D., Bournas, N. and Rabbadi, M.C., 2007 - The Role of Gravity and Aeromagnetic Data in Mapping Mega Gondwana Crustal Lineaments: the Argentina - Brazil - Algeria (ABA) Lineament; SEG 2007, San Antonio, Extended Abstract, 4p.

ARAGUAIA FOLD BELT

The Araguaia Fold Belt represents the northern extension of the Brasilia Belt across the Transbrasiliano Lineament. It is developed along the eastern margin of the Amazonian Craton, whilst the northern two third lies to the west of the cratonic Parnaíba basement block that is entirely concealed beneath the Phanerozoic Parnaíba Basin. This latter block is assumed to be similar in character to the Amazonian Craton. The southern third of the belt is bounded to the east by the Goiás Massif, which by the Mesoproterozoic was accreted onto the São Francisco Craton.
The Araguaia Fold Belt trends north-south, is >1000 km long and is related to the collision, and other complex interactions, between the Amazonian-Parnaíba Cratonic block and combined São Francisco and Congo Cratons (see Fig 1 in the Carajás IOCG Province record). It is exposed over a width of <150 km, overlain to the east by sedimentary cover rocks of the Palaeozoic Parnaíba Basin. To the SW it passes into the Paraguaia Fold Belt which follows the southern margin of the Amazonian Craton. This trio of orogens, the Brasilia, Araguaia and Paraguaia fold belts, together with the Goiás Massif and Goiás Magmatic Arc at their triple junction, form the Tocantins Province.
The main lithostratigraphic unit of the Araguaia Belt is the Baixo Araguaia Supergroup, subdivided into the Neoproterozoic Tocantins Group in the western Outer Zone, immediately to the east of the Amazonia Craton, and the more strongly metamorphosed Mesoproterozoic Estrondo Group in the eastern Inner Zone. The Outer Zone contains ophiolitic slices and fragments developed within a sequence of rift basin sedimentary rocks derived from magmatic arc sources, volcanic rocks, and part of a passive continental margin with low-grade metamorphic rocks, while the Inner Zone corresponds to a pile of low- to medium-grade metasedimentary rocks, again deposited in a principally rift regime. The presence of volcanic derived detritus within the Tocantins Group has been taken to infer the relative proximity of an arc, most likely the Mara Rosa Ark of the Goiãs Magmatic Arc.
The Outer zone is partially separated from the Amazonia Craton by the Tocantins-Araguaia Lineament, which in the north is a WNW vergent thrust that becomes a vertical corridor of shearing to the south. The sequence within this outer zone is composed of psammites and pelites of the Tocantins Group that has been divided into two units. The lower Pequizeiro Formation (Peq), which is found in the eastern half of the Outer Zone, and is in structural contact with the Inner Zone. It is predominantly composed of chlorite schists and chlorite-quartz schist with interbedded calc-shales, talc schists, talc-actinolite schist, serpentinite, meta-mafic rocks and phyllites (Hasui et al., 1977). The chlorite-quartz schist in the eastern part of the belt, close to the tectonic contact with the Inner Zone, is light grey, with anastomosed and/or crenulated foliation, and is fine-grained, with a grano-lepidoblastic texture (Souza and Moreton, 2001). The chlorite schist in the western portion, near the contact with the overlying sequence, is grey-green, fine-grained, lepidoblastic and foliated, with a well-marked crenulation (Bordalo et al., 2020).
The overlying Couto de Magalhães Formation (cdm) to the west, is, in turn, bounded further west by the Amazon Craton. It is predominantly composed of slate, phyllite, meta-siltstone and meta-claystone, with minor quartzite, meta-chert and meta-carbonate rocks, and considerable volumes of polymictic conglomerate lenses and meta-wacke in the west where they are un- to weakly-metamorphosed. As such, these rocks contrast markedly with the amphibolite-grade suites of the Inner Zone, to the east, as described below. Throughout the western section of the belt, the Couto de Magalhães Formation tectonically overlies the Amazonian Craton (Souza and Moreton, 2001), while the contact with the underlying Pequizeiro Formation is a thrust-shear zone (Fonseca et al., 2004).
A number of 'strings' of elongated slices and fragments of north-south aligned serpentinised and/or metamorphosed mafic to ultramafic rocks are surrounded by the Couto de Magalhães Formation in the 'Outer zone' of the Araguaia Fold Belt. They occur as magnesian schists, low-grade carbonates, siliciclastic metasedimentary rocks, peridotite, basaltic pillow lavas and associated ferruginous silexite (an intrusive igneous rock containing >90% quartz). The silexite unit may occur as isolated bodies or in association with serpentinised peridotite and/or magnesian schist. These rocks preserve several sedimentary structures indicative of deep foreland basin deposits (e.g. slump and turbidites, Moura et al., 2008). Individual mafic to ultramafic slices range from hundreds of metres in length up to the largest, the Quatipuru Complex, that is ~40 km long and ~1.5 km wide. The latter comprises serpentinised peridotites composed of a lenticular litho-structural arrangement of predominantly harzburgite with small, sparse, decametric lensoid dunite intercalations. Other significant complexes include the Serra do Tapa and Morro do Agostinho. The age of these rocks is regarded as Neoproterozoic, based on U-Pb ages of ~630 Ma (Osborne 2001) for magmatic zircons from rhyolitic tuffs which are regarded to be related to the ocean-basin volcanism in the proximity of the Quatipuru Complex. The Sm-Nd isochron age of a narrow gabbroic dyke crosscutting harzburgite of the same complex was 757±49 Ma (Paixão et al., 2008). These mafic-ultramafic rocks are interpreted to be predominantly derived from mantle peridotite representing the base of the Moho transition zone. They contain chromitite pods, lensoid dunitic bodies and a suite of mafic-ultramafic dykes and/or sills resulting from partial melting, magma impregnation and diapiric ascent (Paixão et al., 2008). Most have massive internal textures whereas their borders are generally brecciated or have mylonitic foliation parallel to the trend of host Tocantins Group meta-sedimentary rocks. Some authors consider these mafic and ultramafic bodies to represent fragments of ophiolite sequences related to the Neoproterozoic Brasiliano Orogeny or oceanic floor to a passive margin basin (Gorayeb, 1989; Souza et al., 1995; Teixeira, 1996; Kotschoubey et al., 1996). Paixão et al. (2008) interpret the Quatipuru, and similar ophiolites in the belt, which are predominantly composed of mantle peridotite, mainly residual harzburgite, to represent the base of the Moho transition zone introduced during a period of hyper-extension at ~750 Ma.
The supracrustal rocks of the Inner Zone predominantly belong to the Mesoproterozoic Estrondo Group, which commences with the lower Morro do Campo Formation, composed of micaceous quartzite containing magnetite and kyanite, with interbedded layers of biotite schist, quartz-mica schists, graphitic schists and oligomictic meta-conglomerates (Hasui et al., 1977). The quartzite, where intercalated with biotite-muscovite-quartz schist, has a grano-lepidoblastic texture whereby quartz and lamellar biotite aggregates are oriented, deformed and partly replaced by muscovite and chlorite. The overlying Xambioá Formation includes biotite-muscovite schists with interbedded calc-schists, marbles, meta-greywackes and various schists containing garnet, graphite, staurolite, kyanite and fibrolite (Hasui et al., 1977). Detrital zircons in the Morro do Campo Formation, indicate contribution from both Archaean 2909 ±5 and 2668 ±2 Ma) and Palaeoproterozoic 1748 ±5 and 1747 ±6 Ma sources, but none of Neoproterozoic Brasiliano provenance (Paixão et al., 2008). However, the Xambioá Formation has Sm-Nd model ages which point to the contribution of Neoproterozoic 'Brasiliano' rocks (Paixão et al, 2008). This may suggest the Xambioá Formation is a more strongly metamorphosed equivalent of the Tocantins Group.
Both the Estrondo Group and the neighbouring southern Carajas District of the Amazonian Craton are intruded by granitic plutons of the Palaeoproterozoic 1.88 to 1.86 Ga Jamon Suite. These are Rapakivi, A-type granites composed of monzogranite with subordinate syenogranite. Plagioclase mantled K feldspar megacrysts are common, whilst mafic minerals are normally between 15 and 5% in the less evolved facies, and as much as >20%, to <5% in differentiated leucogranites. Typical primary accessory minerals include zircon, apatite, magnetite, ilmenite, allanite and titanite (Dall'Agnol et al., 1999, Oliveira, 2001), with fluorite only significant in the more evolved facies.
In the northern half of the Inner Zone, a 250 km long string of 8 domal structures is developed, exposing ~2.86 Ga Archaean basement of the Colméia Complex in their cores. These cores are surrounded by metamorphosed sedimentary rocks of the Estrondo Group. The largest of these is the Colméia Dome, a WNW elongated, ~35 x 20 km structure. The next largest are the similarly trending 11 x 9 km Xambioá and 20 x 9 km Lontra domes. The Colméia Complex is composed of banded muscovite-biotite and hornblende bearing TTG gneisses that have been variably migmatised, and cut by granitic, granodioritic and trondhjemitic veins and masses, with common small enclaves of feldspathic biotite schist, mica quartzite and amphibolite (Costa, 1980). The granitoids are reddish or grey, and fine to coarse-grained. Both gneisses and granitoids show penetrative foliation and the development of secondary sericite, epidote, chlorite and clay minerals. The granitoids generally predominate in the cores of the windows while the gneisses are more frequent at their peripheries (Bordalo et al., 2020).
The two periods of rifting postulated above, namely the Mesoproterozoic sequence in the northern Inner Zone and the Neoproterozoic succession of the Outer Zone, may reflect separation of the Parnaíba Block from the Amazonian Craton, followed by basin inversion and then renewed divergence.
In the southern half of the Inner Zone, the Estrondo Group overlies larger areas of exposed Archaean to Palaeoproterozoic basement that are bounded to the SE by faults of the Transbrasiliano Lineament. These basement rocks include the:
Rio do Coco Group (Costa et al., 1983), which is the oldest unit in the southern Araguaia Fold Belt, dated at 2.6 Ga (Pb-Pb zircon; Arcanjo 2002), but younger than the Colméia Complex in the north. It is only found in a few restricted areas where it comprises a greenstone belt type metavolcano-sedimentary sequence, divided into i). a lower unit of pelitic and chemical sedimentary protoliths with intercalations of magnesian schists; and ii). an upper unit of feldspathic schists and mafic rocks. The mafic volcanic rocks are komatiitic, intercalated with chemical and pelitic sedimentary rocks, and intruded by alkali-feldspar granites (Costa et al., 1983). Grey-white feldspathic schists contain pyrite, arsenopyrite, rutile, tourmaline and chlorite, alternating with micaceous beds. Among the metapelites there are conspicuous dark grey quartz-mica schists with or without garnet. These rocks include intervals of millimetric banding and penetrative mylonitic foliation (Arcanjo et al., 2013).
Morro do Aquiles Formation, another volcanosedimentary unit within this terrane, underwent upper-amphibolite facies metamorphism at low to middle pressure conditions, and comprises sillimanite and/or andalusite-bearing cordierite gneiss, tonalitic gneisses, graphite schists, gondites and amphibolites which are cross-cut by the Carreira Comprida Anorthosite. This formation is interpreted to represent a mega-slice of tectonically exhumed lower crustal granulite facies rocks that were imbricated and thrust with a west vergence over younger gneisses (Gorayeb et al., 2000). The minimum age of the mafic granulite and enderbite protoliths has been estimated at ~2.1 to 2.15 Ga. The terrane is cut by the 555 to 560 Ma Matança Granite and 548 5 Palmas Granite which places a youngest age on the structural emplacement of the complex (Gorayeb et al., 2000).
Porto Nacional Complex, which is considered to predominantly belong to the Goiás Massif, but largely occurs as structural, shear bounded slivers within the broad Transbrasiliano Lineament, and as such is not part of the Araguaia Fold Belt. It is composed of medium to high pressure granulite facies mafic granulites, enderbites, kyanite and/or sillimanite-bearing garnet gneisses, as well as anatectic granitic bodies, mainly leucoenderbites, trondhjemites and S-type granites. It is part of the NNE-SSW elongated Porto Nacional High Grade Metamorphic Terrane within the Transbrasiliano Lineament.
Rio dos Mangues Complex, which is the most extensive of the basement units. It is composed of migmatised tonalitic, granodioritic and calc-silicate gneisses, with associated granodiorite leucosomes (Souza 1996), garnet biotite paragneisses, orthoquartzites, granite-gneisses and subordinate amphibolites (Costa et al., 1983). The tonalitic gneisses are dark grey, medium to coarse grained, and include quartzo-feldspathic agglomerates. The granodiorite gneisses outcrop in the SE and NW and are light grey, with dominant millimetric to centimetric banding. Garnet-biotite paragneisses are light grey, with a foliation defined by the orientation of fine quartz and feldspar crystals surrounded by biotite to form an alternating centimetric banding. All of these rocks are migmatised to different degrees with restricted pegmatoid veins following the mylonitic foliation. Restricted exposures of alkali-feldspathic granitic and tonalitic orthogneisses are found in the eastern portion of the complex. The Palaeoproterozoic orthogneisses of the Rio dos Mangues Complex were emplaced between 2.05 and 2.08 Ga (Arcanjo et al., 2013). The complex is in contact with the principal outcropping block of the Archaean Rio do Coco Group on its northern extremity, while both are overlain by the Mesoproterozoic Estrondo Group (de Souza et al., 2019; Hodel et al., 2019).
Serrote Granite, which occurs as a 19 km diameter, NNE-SSW elongated elliptical pluton in the central northern Rio dos Mangues Complex (Costa 1985). The pluton contains medium to coarse microcline granites and potassium leucogranites with augen-porphyroid and mylonitic textures (Gorayeb 1996). It has oriented and almond-shaped microcline, plagioclase and quartz phenocrysts set in a fine granoblastic matrix of quartz, microcline, plagioclase and lesser biotite, amphibole and muscovite. Pb-Pb zircon ages of the pluton are ~1861 ±41 Ma (Arcanjo et al., 2013).
Monte Santo Suite, (Costa et al., 1983) comprises two bodies, the Monte Santo and Serra da Estrela plutons, composed of alkaline gneisses that intrude the Rio dos Mangues Complex and Rio do Coco Group, and are partially covered by section of the Estrondo Group. They include nepheline syenites and alkali-syenites, reworked by metamorphism and metasomatism (Iwanuch 1991). They have a grano-lepidoblastic texture with a NE-SW oriented quartz-feldspathic aggregates with a low dip and millimeter bands of biotite. The mylonitic foliation has a WSW stretching lineation. These have Sm/Nd model ages ranging between 1.70 and 1.49 Ga and a Mesoproterozoic Pb-Pb age of 1.0 Ga (Arcanjo and Moura, 2000).
Matança Granite (Costa et al., 1984) which intrudes the Transbrasiliano Lineament zone and encroaches onto the southern margin of the Araguaia Fold Belt. It occurs as batholiths of foliated, microcline-rich porphyritic and mylonitic granitoids that vary from alkali-feldspar granite, syenogranite, quartz monzonite to granodiorite. It has been dated as 560 to 555 Ma (Gorayeb 1996).
Other Neoproterozoic granitoids were intruded during the Brasiliano Event, preceding and coinciding with the inversion of the Araguaia basin. These include the 660 Ma Santa Luzia Granite (Moura and Gaudette 1993; Moura et al., 2000); Cambro-Ordovician 513 ±17 Ma granitic dykes; and the 550 Ma Lajeado and Palmas plutons in southeastern Tocantins State. Some granites have mylonitic margins related to shear zones within the Transbrasiliano Lineament (Gorayeb et al., 2000).
Deformations - Fonseca et al. (2004) interpret two phases of deformation to have affected the Araguaia Fold Belt. D1 produced a north-trending foliation that dips to the E and is related to oblique sinistral thrusting, with structural vergence towards the Amazonian Craton. This phase is well developed in the meta-sedimentary rocks of the Estrondo Group in the Inner Zone of the Araguaia Belt, and was accompanied by amphibolite facies metamorphism, and may be a Palaeoproterozoic event. D2 is represented by orogen-parallel wrench tectonics leading to the development of vertical north-south trending shear zones, overprinting D1 in the Estrondo Group, and was responsible for retrograde metamorphism in the inner zone. D2 is regarded to be a Neoproterozoic deformation. An intervening phase of doming is inferred, due to the existence of extensional fabric around the domes, which are most likely metamorphic core complexes associated with the extensional domain associated with deposition of the Tocantins-Brasilia rift basin.

A generalised traverse across the Araguaia Fold Belt, from east to west commences with the ~2.86 Ga Colméia Complex exposed in probable metamorphic core complex domes in the northern half of the Inner Zone. To the south, the 2.6 Ga Rio do Coco Group outcrops over a limited area, in contact with a much more extensive basement occupied by the surrounding ~2.1 to 2.15 Ga Porto Nacional Complex and the 2.08 to 2.05 Ga Rio dos Mangues Complex, both of which are principally of magmatic origin. All of these rocks are overlain throughout the Inner Zone by the meta-sedimentary Estrondo Group sedimentary succession, comprising the late Palaeoproterozoic to Mesoproterozoic Morro do Campo Formation and the overlying, probable Neoproterozoic Xambioá Formation. These rocks are structurally overlain in the Outer Zone by the Neoproterozoic Tocantins Group, a sequence of sedimentary rocks derived from both magmatic arc and passive continental margin sources. The outer zone sequences have been thrust westward over the eastern margin of the Amazonian Craton. The Estrondo Group and Amazonian Craton are intruded by ~1.88 to 1.86 Ga Late Palaeoproterozoic A-type granitoids of the Jamon Suite and the Rio dos Mangues Complex by the ~1.86 Ga Serrote Granite, whilst Neoproterozoic granitoids are found in association with the Transbrasiliano Lineament where it cuts the Araguaia Fold Belt.
The geotectonic history of the Araguaia Fold Belt has involved a number of successive cycles of compression and extension. The Meso- to Neoarchaean Colméia Complex and Rio do Coco Group that represent the eastern Archaean basement to the Araguaia Fold Belt are assumed to have been accreted to the eastern margin of the Amazonian Craton during the Palaeoproterozoic, most likely representing the leading edge of the more extensive, concealed, cratonic Parnaíba Block. This compressional accretionary event is possibly reflected by the Rio dos Mangues and Porto Nacional complexes representing a magmatic arc associated with that amalgamation. This collisional event appears to have been followed by a period of relaxation, extension, crustal attenuation and rifting. In the northern Araguaia Fold Belt this extension triggered a concomitant major mantle upwelling event below the newly formed suture zone on the eastern margin of the Amazonian Craton between 1.88 and 1.86 Ga in the Palaeoproterozoic. This resulted in granulite facies metamorphism, migmatisation and a magmatic event that produced the A-type granites of the Jamon suite and the Serrote Granite. This major magmatic event implies a high-temperature thermal regime that may have favoured intense melting of the subcrustal lithospheric mantle (SCLM), leading to its strong depletion (Hodel et al., 2019). This period of extension and magmatism was also accompanied by deposition of the Morro do Campo Formation of the Estrondo Group in a rift regime during the late Palaeo- to early Mesoproterozoic. This extensional rifting and thermal event appears to have transitioned into a sinistral transpressive regime that produced NW vergent thrusting of the Morro do Campo Formation towards the Amazonian Craton. At this stage, the Amazonian and São Francisco cratons were separated by the wide Goiás-Pharusian Ocean in the south half of the Araguaia Fold Belt. To the north, this broad ocean split into two arms. The first of these formed a narrower, north-south trending seaway that had opened during the extensional phase when the Amazonian Craton and the previously accreted cratonic Parnaíba Block were separated, and was the locus of the northern half of the Araguaia Fold Belt. The second was oriented NE-SW and separated the São Francisco Craton and the Parnaíba Block and floored by basement deposited at @1.9 Ga. This arm was later to be the locus of the Transbrasiliano Lineament.
At some time after ~1.2 Ga, in the Stenian Period of the late Mesoproterozoic, the Mara Rosa Magmatic Arc was initiated in the southern half of the Araguaia Fold Belt. It formed over the eastern oceanic leading edge of the Amazonian Plate, above a west dipping intra-oceanic subduction zone within the main Goiás-Pharusian Ocean which migrated east, consuming the oceanic crust outboard of the Goiás Massif. This arc was predominantly formed between 900 and 850 Ma (Cordani et al., 2013) in the Tonian of the Early Neoproterozoic, before colliding at ~800 Ma (Laux et al., 2004, 2005) with the Goiás Massif, which at that stage formed the eastern margin of the São Francisco Craton. Collision and overthrusting of the Mara Rosa Arc onto the Goiás Massif and the resultant imbrication was followed by slab break-off, delamination and detachment of the SCLM below the massif, then uplift and tectonic rebound between 800 and 770 Ma (Cordeiro and Oliveira, 2017). At much the same time, Hodel et al. (2019), Paixão, et al. (2008) and Dilek and Thy (1998), propose this reversal transitioned to a second episode of hyper-extension on the eastern margin of the Araguaia Fold Belt at ~750 Ma. This extension resulted in crustal attenuation and necking of the crust to separate the Amazonian Craton and the Colméia Complex/Rio do Coco Group (on the leading edge of the Parnaíba Block) along the Palaeoproterozoic suture between the two blocks. They propose the necking allowed the updoming, erosion of cover and exhumation of the underlying SCLM to shallow levels. The Neoproterozoic Tocantins Group was deposited in the rift formed over this zone of crustal attenuation, whilst rift deposition was also taking place in the Rio Preto Fold Belt between the Parnaíba Block and the São Francisco Craton. The crustal thinning in the northern Araguaia Fold Belt also again induced asthenospheric upwelling below the SCLM, thus producing a strong heat gradient that melted the lower SCLM to form E-MORB intrusions such as that of the Quatipuru Complex; localised serpentinisation in the upper SCLM that had been modified during the Palaeoproterozoic upwelling event; and melting of peridotite in the latter to produce the localised N-NORB pillow basalt lava observed in the sequence hosting the Serra do Tapa and Morro do Agostinho ophiolitic intrusions/units.
This extension was followed by the renewal of oblique convergence between the Mara Rosa Arc and the Goiás Massif after ~750 Ma, and the overthrusting and imbrication of the Arenópolis Arc over the southwestern margin of the Goiás Massif, coincided with the inversion of the Tocantins rift basin by 660 Ma. This inversion corresponded to two phases of deformation: i). a first phase of sinistral, WNW vergent thrusting of the western margin of the Mara Rosa Arc over the Araguaia Fold Belt to the NW in the opposite sense to the earlier compression; this resulted in the 'flower-structure' inward dipping tectonic boundaries of the arc; and ii). a second phase of overthrusts with associated lateral ramps (Hasui and Costa 1990; Abreu et al., 1994; Costa and Hasui 1997; Fonseca et al., 2004) represented by Brasiliano age transcurrent, ductile-brittle shear zones of the Transbrasiliano Lineament (Paixão, et al., 2008). This imbrication, followed by post orogenic relaxation and extesion produced a series of Ediacaran to Cambrian granites within the Araguaia Fold Belt, Transbrasiliano Lineament zone and Goiá Magmatic Arc. The oblique relationship between the major north-south structural trend of the Araguaia Fold Belt and the NE-SW to NNE-SSW trend of the Transbrasiliano Lineament, both of which accommodated lateral movement, has implications for transpressional and transtensional dilation within the belt.

Araguaia Fold Belt References
Arcanjo, S.H.S., Abreu, F.A.M. and Moura, C.A.V., 2013 - Evolução geológica das sequências do embasamento do Cinturão Araguaia na região de Paraíso do Tocantins (TO), Brasil; Brazilian Journal of Geology, São Paulo, v.43, pp. 501-514.
Barros, L.D. and Gorayeb, P.S.d.S., 2019 - Serra do Tapa Ophiolite Suite - Araguaia Belt: Geological characterization and Neoproterozoic evolution (central-northern Brazil); Journal of South American Earth Sciences, v.96, 14p. doi.org/10.1016/j.jsames.2019.102323.
Bordalo, R.A., Santos, T.J.D. and Dantas, E.L., 2020 - Structural evolution and U/Pb zircon age of the Xambioa gneiss dome, contributions to the Araguaia fold belt tectonic history; Journal of South American Earth Sciences, v.104, 14p. doi.org/10.1016/j.jsames.2020.102753.
Dall'Agnol, R., Teixeira, N.P., Rämö, O.T., Moura, C.A.V., Macambira, M.J.B. and Oliveira, D.C., 2005 - Petrogenesis of the Paleoproterozoic rapakivi A-type granites of the Archean Carajás metallogenic province, Brazil; Lithos v.80, pp. 101-129. doi.org/10.1016/j.lithos.2004.03.058.
Fonseca, M.A., Oliveira, C.G. and Evangelista, H.J., 2004 - The Araguaia Belt, Brazil: Part Of A Neoproterozoic Continental-Scale Strike-Slip Fault System; Journal of the Virtual Explorer, v.17, Paper 6, 16p.
Fuck, R.A., Dantas, E.L., Pimentel, M.M., Botelho, N.F., Armstrong, R., Laux, J.H., Junges, S.L., Soares, J.E. and Praxedes, I.F., 2014 - Paleoproterozoic crust-formation and reworking eventsin the Tocantins Province, central Brazil: A contributionfor Atlantica supercontinent reconstruction; Precambrian Research, v.244, pp. 53-74. doi.org/10.1016/j.precamres.2013.12.003.
Gorayeb, P.S.d.S., Moura, C.A.V. and Barros, G.B., 2000 - Pb-Pb Zircon ages of the Porto Nacional high-grade metamorphic terrain, northern portion of the Goiás Massif, Central Brazil; Revista Brasileira de Geociências, v.30, pp. 190-194.
Hodel, F., Trindade, R.I.F., Macouin, M., Meira, V.T., Dantas, E.L., Paixão, M.A.P., Rospabé, M., Castro, M.P., Queiroga, G.N., Alkmim, A.R. and Lana, C.C., 2019 - A Neoproterozoic hyper-extended margin associated with Rodinia's demise and Gondwana's build-up: The Araguaia Belt, central Brazil; Gondwana Research, v.66, pp. 43-62.
Moura, C.A.V., Pinheiro, B.L.S., Nogueira, A.C.R., Gorayeb, P.S.d.S. and Galarza, M.A., 2008 - Sedimentary provenance and palaeoenvironment of the Baixo Araguaia Supergroup: constraints on the palaeogeographical evolution of the Araguaia Belt and assembly of West Gondwana; in Pankhurst, R.J., Trouw, R.A.J., Brito Neves, B.B. & De Wit, M.J. (Eds.), West Gondwana: Pre-Cenozoic Correlations Across the South Atlantic Region. Geological Society, London, Special Publications, v.294, pp. 173-196. doi:10.1144/SP294.10.
Paixão, M.A.P., Nilson, A.A. and Dantas, E.L., 2008 - The Neoproterozoic Quatipuru ophiolite and the Araguaia fold belt, central-northern Brazil, compared with correlatives in NW Africa; in Pankhurst, R.J., Trouw, R.A.J., Brito Neves, B.B. & De Wit, M.J. (Eds.), West Gondwana: Pre-Cenozoic Correlations Across the South Atlantic Region. Geological Society, London, Special Publications, v.294, pp. 297-318. doi:10.1144/SP294.16.
Pimentel, M.M., 2016 - The tectonic evolution of the Neoproterozoic Brasília Belt, central Brazil: a geochronological and isotopic approach; Brazilian Journal of Geology, v.46(Suppl 1), pp. 67-82, June 2016.
Souza, C.D.S.M., Hauser, N., Dantas, E.L., Reimold, W.E., Schmitt, R.T., Chaves, J.G.S. and Osorio, L.F.B., 2019 - Does the metavolcanic-sedimentary Rio do Coco Group, Araguaia Belt, Brazil, represent a continuity of the Quatipuru ophiolitic complex? - Constraints from U-Pb and Sm-Nd isotope data; Journal of South American Earth Sciences, v.94, 18p. doi.org/10.1016/j.jsames.2019.102233.

PARNAÍBA BASIN AND BLOCK

The Parnaíba Basin covers a generally ellipsoidal area of ~0.6 million km², and comprises up to 3.5 km of mainly post-Ordovician Phanerozoic sedimentary rocks in its depocentre. This sequence overlies a number of late Neoproterozoic to early Palaeozoic rifts developed within the Precambrian crystalline basement, the upper part of a relatively thick 160 to 180 km thick lithosphere (McKenzie and Priestley, 2008). The northern boundary of the basin comprises the São Luís Craton and its southern marginal Gurupi Fold Belt (Fig. 1). To the west, it abuts the Araguaia Fold Belt on the rifted margin of the Amazonian Craton. To the south and SE is overlies the amalgamated Archaean to Palaeoproterozoic Goiás Massif and São Francisco Craton and the Meso- to Neoproterozoic Brasilia Fold Belt. To the east it overlies the Borborema Province.
The basin is largely underlain by the triangular basement Parnaíba Block, which is bounded by steep north-south, east-west and SW-NE crustal-scale boundaries that are reflected by abrupt changes in seismic character (Daly et al., 2012). The southeastern margin, the SW-NE hypotenuse of the triangle, corresponds closely to the Transbrasiliano Lineament. Along the western boundary, the Amazonian/Araguaia Block terminate eastward against a steep, north-south trending, east dipping inferred fault zone defining the boundary of both the Parnaíba Block and the overlying Parnaíba Basin Phanerozoic sedimentary succession. Truncation of the latter reflects reactivation of the underlying Neoproterozoic structural margin during the Late Triassic and Late Jurassic to Early Cretaceous, when the basement was folded and elevated by more than 2 km. Little is known of the lithologies of the Parnaíba Block, other than it is seismically transparent, without the well defined texture evident in the Amazonian/Araguaia and Borborema Province on either side which terminate abruptly across planar discontinuities into the featureless Parnaíba Block. It is assumed to represent Archaean to Palaeoproterozoic intrusive and metamorphic rocks (Daly et al., 2012; Castro et al., 2014), possibly related to the São Luis and Amazonian cratons that characterise the northwestern side of the Transbrasiliano Lineament, or also possibly rocks related to the São Francisco Craton and Goiás Massif, that have been offset along the Transbrasiliano Lineament during the Proterozoic and Phanerozoic.
On the basis of gravity data, Nunes (1993) divided the basement inlier in four crustal segments, separated by a series of NW-SE trending graben-like structures. Various authors suggest these rifts are either Neoproterozoic Brasiliano structures filled with late Neoproterozoic to early Palaeozoic sequences (e.g., Fuck et al., 2008), or Proterozoic succession within pre-Brasiliano grabens (e.g., Nunes, 1993).
The Neoproterozoic Rodinia break-up reactivated major pre-existing zones of weakness, particularly the Brasiliano ductile shear zones of the underlying Borborema Province, to produce a second suite of rift/grabens. In contrast, these structures trend NE-SW to east-west and carry Cambrian to Ordovician sequences, as exposed to the SE of the Transbrasiliano Lineament (Brito Neves, 2002; Oliveira and Mohriak, 2003). These grabens contain thick units of immature clastic sedimentary and bimodal volcanic rocks, intruded by granite (Castro et al., 2014).
The base of the post-Ordovician sedimentary succession is a pronounced, planar, regional unconformity that crosses the Amazonian/Araguaia, Parnaíba Block and the Borborema Province. However, this unconformity has been displaced by younger steep Mesozoic to Cenozoic faulting. The Phanerozoic Parnaíba Basin encompasses four successive sub-basins, each with distinct genesis and ages, namely:
i). a cratonic sag sub-basin, filled with Ordovician to early Triassic marine sedimentary rocks, mostly thick epicontinental siliciclastic sequences, separated by widespread unconformities (Góes et al., 1990);
ii). an intermediate interior fault controlled basin, which contains continental sedimentary rocks and extensive Jurassic and Cretaceous basaltic flows and dykes (Merle et al., 2011). This marked the beginning of the disintegration of Pangea, and was accompanied by subsidence in the central portion of the Parnaíba Basin as ENE- and NNE-oriented rifts. These basaltic lava flows and dykes formed the lower and upper margins of a sequence of Jurassic fluvial to aeolian sedimentary sequence (Góes et al., 1990). Cretaceous kimberlite pipes were also injected, mainly along the Transbrasiliano Lineament (Kaminsky et al., 2009);
iii). two sub-basins, on the northern and southern province edges, in which marine and desert sequences were respectively deposited (Pedreira da Silva et al., 2003). This was initiated by a broad Aptian-Albian Early Cretaceous uplift in the central area of the Parnaíba Basin, triggering continental sediment deposition (Castro et al., 2014);
iv). Urucuia (or Sanfranciscana) Basin which resulted from a more intensive phase of stretching, associated with thermal subsidence, led to expanded deposition after the Albian as the South Atlantic began to open. This formed a long and narrow north-south rift basin over the southern edge of the Parnaíba Basin and along the western border of the São Francisco Craton. Other Cenozoic sedimentation overlies large areas of the Parnaíba Basin and the surrounding Precambrian basement (Castro et al., 2014).

Parnaíba Basin and Block References
de Castro, D.L., Fuck, R.A., Phillips, J.D., Vidotti, R.M., Bezerra, F.H.R. and Dantas, E.L., 2014 - Crustal structure beneath the Paleozoic Parnaíba Basin revealed by airborne gravity and magnetic data, Brazil; Tectonophysics, v.614, pp. 128-145.
Daly, M. C., Andrade, V., Barousse, C.A., Costa, R., McDowell, K., Piggott, N. and Poole, A.J., 2014 - Brasiliano crustal structure and the tectonic setting of the Parnaíba basin of NE Brazil: Results of a deep seismic reflection profile, AGU Tectonics, v.33, pp. 2102-2120, doi:10.1002/2014TC003632.

PARAGUAIA FOLD BELT

The Paraguaia Fold Belt is largely composed of Neoproterozoic sedimentary rocks deposited during an extensional event, followed by inversion that was characterised by deformation and magmatism, and then by collision between the Amazonian Craton and Paranápanema Block in the north, and the Rio Apa section of the Rio de la Plata Craton from the SW. Prior to inversion, the original extensional depositional basin is estimated to have reached ~350 km in width, before being compressed to as little as ~130 km during the intense shortening associated with the Brasiliano orogenesis (Silva, et al., 2021). The belt is divided into three structural domains (e.g., Barboza, et al., 2018):
i). Internal zone to the SE, characterised by NW vergent, strong to isoclinal folding and low grade metamorphism to greenschist facies. It is composed of metavolcano-sedimentary rocks, turbidites and glaciogenic sequences that have been intruded by post‑orogenic granitoids. Much of this zone is concealed by the Paraná Basin and the Cenozoic Pantanal Basin/swamp.
ii). External or Pericratonic zone which is not metamorphosed and is characterised by open folding and NW vergent reverse/thrust faulting. It is composed of glaciogene rocks at the base of the sequence, and carbonates and terrigenous sedimentary rocks at the top;
iii). Cratonic-platform zone with generally sub-horizontal dips, gentle folding and fault structures and non‑penetrative brittle tectonics. The upper, molassic part of this sequence has lapped onto, or been partially thrust over the Amazonian Craton in the north and NW;
The boundary between the internal and external zones is marked by both high angle reverse fault zones and by normal faulting, and may mark the transition from continental to continental slope regimes.
Deposition of the sequence of the Paraguaia Fold Belt took place in an extensional regime in a composite basin, partially floored by oceanic crust between 800 and 550 Ma. The basin is bounded by the Amazonian Craton to the NW and by the São Francisco Palaeo-continent and Paranápanema Block to the east and SE, and the Rio Apa section of the Rio de la Plata Craton to the SW. The stratigraphic section has been variably subdivided by different authors, whilst the belt has been subdivided into a northern and southern half, separated by the vast Cenozoic Pantanal swamp/basin.

The Northern Paraguaia Fold Belt sequence may be summarised as follows, from the base:
• Nova Xavantina meta-volcano-sedimentary sequence, which is variously described as a separate unit (e.g., Pinho, 1990; Martinelli,1998), or the lowest member of the Cuiabá Group (e.g., Almeida, 1974; Ruiz and Santos, 1999), is found in the eastern part of the Internal zone, emplaced in a rift environment (Silva, 2007). The sequence is composed of bimodal mafic and ultramafic volcanic and felsic pyroclastic rocks, intercalated with argillites and sandstones, as well as chemical sediments, chiefly banded iron formation and chert. The volcanic facies include dark grey-green alkali-basalts, greenish-grey vesicular, subaerial mafic lavas containing bombs, whitish yellow quartz-rich sericite/phengite altered pyroclastic rocks, including ignimbrites, scoria, lapilli tuffs and altered dacitic volcanic glass, as well as dykes and sills of chlorite and epidote altered gabbro with MORB-like lithochemistry (Pinho, 1990; Martinelli, 1998; Silva 2007; Barboza, et al., 2018). Metavolcanic felsic rocks of the explosive volcanism has been dated at ~750 Ma (U-Pb zircon SHRIMP; Dantas et al., 2007), whilst 3 zircons from the explosive mafic rocks were dated at 822  ±9 Ma (Babinski et al., 2018). The Nova Xavantina sequence is also known as the Araés meta-volcano-sedimentary sequence (Martinelli and Batista, 2003).
• Cuiabá Group - which outcrops over a wide area in the southern and eastern portion of the orogen. It is generally composed of organic-rich phyllites and meta-dolostone, overlain by glaciogenic and turbiditic meta-sediments that include diamictites, conglomerates, quartzite, phyllite, meta-greywacke and meta-arkose. Detrital zircon dating reveals ages ranging from 2253 to the youngest of 652 ±5 Ma, with the main source being attributed to the Amazonian Craton and a subordinate younger source (Dantas et al., 2009; Babinski et al., 2018). The diamictites of the Cuiabá Group are interpreted to be related to the global 636 Ma Marinoan glaciation event (Babinski et al., 2018).
Within the Internal Zone, where it is thicker, Luz et al. (1980) divided the Cuiabá Group into nine units, as follows: i). alternating sericitic and graphitic phyllite and meta-sandstone; ii). feldspathic meta-sandstone, greywacke and graphitic phyllite with alternating limestone; iii). phyllite, with layers of meta-conglomerate and meta-greywacke, with alternations of quartzite and lenses of limestone with hematite at the top; iv). meta-diamictite with polymictic clasts and a silt-sandy matrix; v). phyllite and sericitic phyllite with alternations of feldspar-rich meta-sandstone and meta-conglomerate; vi). conglomerate and phyllite; vii). diamictite with subordinate sandstone; viii). limestone with dolostone and metapelite lenses on the top; and ix). undivided quartzite, phyllite, meta-sandstone and marble. Of these, units i). and ii). represent the upper part of the rift phase that produced the Nova Xavantina sequence, iii). to vii). are turbiditic and glacio-marine lithologies representing tectonic instability, whilst viii). and ix). are carbonate units reflecting tectonic quiescence. Units iv). and vii). are the principal glacial stages in a marine environment (Alvarenga, 1998; Alvarenga and Saes, 1992; Luz et al., 1980), also known as the Bauxi and Puga formations respectively (e.g., Silva, et al., 2021; Vasconcelos et al., 2015). The boundaries between these nine units are diachronous due to the tectonic instability and resultant transgressions and regressions (e.g., Babinski, et al., 2018).
Alternatively, Tokashiki and Saes (2008) divided the Cuiabá Group into the basal Campina de Pedra Formation corresponding to units i). and ii)., which from the base to the top comprises >2000  m of phyllite, graphitic phyllite, intercalations of meta-arenite with incomplete Bouma cycles, calcitic marble and feldspathic meta-greywacke; the Acorizal Formation, which unconformably overlies the Campina de Pedras Formation and represents the glacial-marine sedimentary pile accumulated in a continental margin, equivalent to units iii). to v).; and the Coxipo Formation which is predominantly composed of conglomerate, meta-arenite, quartzite, marble and meta-diamictite, with considerable lithological variation, and is equivalent to units vi). to viii).. The Campina de Pedra and Acorizal formations are only exposed in the Internal Zone, whilst the Coxipo Formation straddles both the Internal and External zones (e.g., Vasconcelos et al., 2015).
• Araras Group - a carbonate unit that covers the diamictite of the Puga Formation above a sharp contact, and is correlated with unit viii)> of the Cuiabá Group. It has been subdivided into the Guia and overlying Noble formations, composed respectively of bituminous deep ocean shale and limestone, and dolostone. Pb-Pb radiometric analyses of the base of Araras Group yield an age of 627 ±30 Ma (Babinski et al., 2006). The Guia Formation is also equated with the Guia facies of the upper Coxipo Formation above. The upper Araras Group is occupied by the Serra Azul Formation, which is composed of massive diamictite at the base, overlain by a sequence of mudstone, siltstone and sandstone at the top. The diamictite is correlated with the ~580 Ma Gaskiers Glaciation (Figueiredo et al., 2004). Exposures of the Araras Group and Puga Formation are largely restricted to the External and Cratonic zones.
• Alto Paraguaia Group - the uppermost unit of the Northern Paraguaia Fold Belt, unconformably overlying the Cuiabá/Coxipo/Araras groups and, like the Araras Group is restricted to the External and Cratonic zones. It is characterised by continental molassic sedimentation, surrounding restricted exposures of Puga Formation diamictites and the Araras Group limestone which are overlain by conglomeratic sandstones of the Raizama Formation, and reddish rhythmites and fine sandstones of the Diamantino Formation.

The Southern Paraguaia Fold Belt may be summarised as follows, from the base:
• Basement RIO APA CRATON which was formed between 1.95 and 1.75 Ga, with interpreted remnant 2.2 to 1.95 Ga oceanic crust. It is variously described as a northern extension of the Rio de la Plata Craton, or the southern part of the Amazonian Craton. The latter is separated from the Rio Apa Block by the WNW trending, ~200 km wide, Neoproterozoic Chiquitos-Tucavaca Aulacogen/Rift which branches off the Paraguaia Fold Belt to the north of Corumba and contains a very similar Neoproterozoic sequence. Lacerdo et al. (2020) suggest the Rio Apa Block represents a Late Palaeoproterozoic continental arc built at ~1.8 to 1.7 Ga, divided into three main sectors by orogenic accretionary events and continental crustal reworking. The western sector comprises Orosirian (i.e., 2.05 to 1.80 Ga) banded orthogneisses of the Porto Murtinho Complex, intruded by early phase granitoids of the 1.88 to 1.71 Ga Amoguijá arc. The central sector contains weak to moderately deformed granites of the same suite, dacitic to rhyolitic metavolcanic rocks of the Serra da Bocaina Formation, the Serra da Alegria gabbro-anorthosite suite, and a gabbro, all overlain by sedimentary rocks. The eastern segment comprises a backarc basin, intruded by late to post-orogenic granites of the Rio Apa Complex, including A-type granites. All of these are of Palaeoproterozoic age. All are intruded by the 914 ±9 Ma Rio Perdido mafic dykes and sill swarms related to a late extensional. Two metamorphic-deformational events are recorded, the first at ~1.67 Ga, followed by thrust deformation and metamorphism interpreted to be related to the ~1.3 Ga Rondonian-San Ignácio event.
• Jacadigo Group - which is 150 to 700 m thick, and overlies the Rio Apa basement with an angular unconformity. It comprises:
The Urucum Formation - a basal conglomeratic and sandy braided stream deposits containing volcanogenic detritus and arkose beds. The lower section of this formation is mainly diamictite/conglomerate and siltstones, whilst the upper segment is predominantly sand-sized facies, with reworked hematitic, silt- to pebble-sized mud rip-up clasts. The latter grades upwards into a marine setting in the lower portion of the overlying Santa Cruz Formation, where the first ice-rafted dropstones appear (Trompette et al., 1998).
The Santa Cruz Formation comprises hematite-rich banded iron formation with manganese oxide intercalations and lens of diamictite containing boulder size ice-rafted dropstones. It is interpreted to have been deposited in a marginal rift basin to shelf, occurring as iron and manganese-rich sediments overlying the fluvial deposits of the Urucum Formation. These sediments were essentially composed of iron, silica and carbonate, and form banded iron formations and ironstones with jasper, hematite and carbonate, interspersed with layers of manganiferous, arkosic, fine to coarse grained clastic sediments and conglomerates. The maximum thickness of the formation recorded in drilling is 396 m. Polgári et al. (2021) state that it has been established that the Santa Cruz Formation is Ediacaran, aged ~547 ±3 Ma (³⁹Ar/⁴⁰Ar; after Piacentini et al., 2013), consistent with the presence of Corumbella fossils (Biondi and Lopez, 2017; Biondi et al., 2020), estimated at ~550 Ma. See the Coromba - Urucum record for more detail.
The Jacadigo Group is correlated with the Cuiabá Group of the Northern Paraguaia Fold Belt. The iron formation of the Santa Cruz Formation is both interbedded with, and overlain by, pebble to boulder glacial diamictite of the Puga Formation equivalents, the lowest unit of the overlying Corumbá Group.
• Corumbá Group - a carbonate rich succession which includes Puga Formation equivalents at the base that are both interbedded with, and overlie, the Santa Cruz iron formation. The diamictites are overlain by the carbonate facies succession that is regarded to be equivalent to the Araras Group of the Northern Paraguaia Fold Belt (Trompette et al., 1998; Silva et al., 2016), such that the Araras-Corumbá carbonate platform is continuous along the southern and eastern margins of the Amazon craton and Rio Apa Block and into the Chiquitos-Tucavaca Aulacogen/Rift. Freitas et al. (2011) report the presence of Ediacaran fossils Corumbá Group. This group has been subdivided into the:
- Cadiueus/Puga Formation - glacio-marine diamictite, overlain by glacial outwash deposits. The top of the Puga diamictite is marked by an erosional surface that has been intensely pyritised and chloritised during burial diagenesis. This surface is overlain by an 18 m thick, light grey, intraclast-bearing, granitic gneiss-pebble to cobble conglomerate that is pervasively trough-cross-bedded. This is interpreted to represent melt-water outwash deposited in an alluvial fan to braided stream regime (Gaucher et al., 2003). The youngest detrital zircon from this formation has been dated at 706 ±9 Ma (U-Pb zircon; Babinski et al., 2013), a 695 ±17 Ma from within shaly beds in the Urucum district iron formation succession (Frei et al., 2017).
- Cerradinho Formation - 60 m of dropstone-rich shallow, tidal, shelf-marine facies sandstone and rhythmites, comprising dark-grey to black, thinly bedded, chlorite-rich, feldspathic sandstones with interbedded black laminated siltstone. The sandstone is ripple-cross-laminated, punctuated by pebble-sized granitic to gneissic dropstones, with peloids of francolite (a carbonate rich variety of fluorapatite) and flaser bedding (Hiatt, et al., 2020).
- Bocaina Formation - dominantly stromatolite-rich dolostone to dolomitic limestone and limestone, sometimes silicified and oolitic, representing a regionally extensive shallow and warm water carbonate platform. Godoi et al. (2001) described it as follows: it is the most extensive unit of the Corumbá Group and is generally at least 300 m thick, but may be as much as 1000 m, with ~350 m of limestone to dolomitic limestone and 300 m of dolostone. It has transitional contacts with the Cerradinho and Tamengo below and above respectively, but also oversteps the former to rest directly on the Jacadigo Group and Rio Apa basement. Dolostone and dolomitic limestone predominate with subordinate calcitic limestone and marble. The dolomitic rocks are generally silicified, recrystallised and locally brecciated, and vary from light to dark grey. They are fine to medium grained, and range from massive to varieties with plane-parallel and cross bedding, with common oolitic and pisolitic textures. Layers are tabular, wavy, and sometimes wedge-shaped, with thicknesses ranging from 5 cm to 1 m. Calcitic limestones, which are dark grey in colour, include calcirudites, calcarenites and calcilutites, and are subordinate and intercalated with dolomitic varieties. Marbles always occur in areas of faulting. The formation contains Collenia-type stromatolites and algal remains (Almeida, 1957; 1965).
- Tamengo Formation is an ~200 m thick carbonatic-clastic sequence that discordantly overlies the Bocaina Formation. It is characterised by black limestones, grainstones and organic siltstones, and is predominantly composed of limestone with subordinate shales, siltstones and sandstones, as well as intercalations of marl and volcanic ash. Carbonate breccias of sedimentary and/or tectonic origin are also evident. Dark grey to black calcitic limestone occur as calcarenites, calcisiltites and calcilutites, mostly crystalline, sometimes oolitic, with associated mixed carbonate and siliciclastic deeper-water facies that include bituminous limestone (Godoi et al., 2001; Walde et al., 2015). Silicification is less intense than in the carbonates of the Bocaina Formation. Sandstones are dark grey, fine- to medium-grained and micaceous, with calcareous cement. They are cross-bedded with ripple marks which are almost always associated with interbeds of siltstones intercalated with limestones. Siltstone and shale are generally greenish to brownish in colour, and form thin, but locally up to tens of metres thick layers and lenses, interspersed with the limestone. The sequence is interpreted to have been deposited on a carbonate platform, with sea level oscillations/tectonic activity, resulting in subtidal to subaerial exposure (Godoi et al., 2001). The formation is restricted to an area of 90 km² near Corumbá and has a minimum thickness of ~200 m. The volcanic ash within the formation have been dated at 543 ±3 Ma (U-Pb zircon, Babinski et al., 2008; Boggiani et al., 2010).
- Guiacurus Formation, a thick succession of grey laminated siltstones and finer-grained pelite that both overlies, and is laterally equivalent, to the Tamengo Formation. It comprises a transgressive high-stand that drowned the carbonate shelf of the Tamengo Formation. The base of the Guiacurus Formation is interpreted to lie on or close to the base of the Cambrian (Walde et al., 2015). The uppermost Tamengo and the Guiacurus Formation are correlated with the Alto Paraguaia Group of the Northern Paraguaia Fold Belt.

Paraguaia Fold Belt References
Babinski, M., McGee, B., Tokashiki, C.C., Tassinari, C.C.G., Saes, G.S., Egidio, F. and Pinho, C., 2018 - Comparing two arms of an orogenic belt during Gondwana amalgamation: Age and provenance of the Cuiabá Group, northern Paraguay Belt, Brazil; Journal of South American Earth Sciences, v.85, pp. 6-42. doi.org/10.1016/j.jsames.2018.04.009. (https://www.sciencedirect.com/ science/article/pii/S0895981117302766.
Barboza, E.S., Santos, A.C., Pinho, F.E.C., Fernandes, C.J., Geraldes, M.C., 2018 - Paraguay Belt lithostratigraphic and tectonic characterization: implications in the evolution of the orogen (Mato Grosso-Brazil). Journal of Sedimentary Environments, Universidade do Estado do Rio de Janeiro, v.3 (2): pp. 54-73.
Frei, R., Dossing, L.N., Gaucher, C., Boggiani, P.C., Frei, K.M., Arting, T.B., Crowe, S.A. and Freitas, B.T., 2017 - Extensive oxidative weathering in the aftermath of a late Neoproterozoic glaciation – Evidence from trace element and chromium isotope records in the Urucum district (Jacadigo Group) and Puga iron formations (Mato Grosso do Sul, Brazil); Gondwana Research, v.49, pp. 1-20.
Lacerda Filho, J.V., Fuck, R.A., Ruiz, A.S., Dantas, E.L., Rodrigues, J.B. and Scandolara, J.E., 2020 - Rio Apa Block: A Juvenile Crustal Fragment in the Southwest Amazonian Craton and Its Implications for Columbia Supercontinent Reconstitution; The Journal of Geology, v.128, doi.org/10.1086/710999.
Polgari, M., Biondi, J.C.,Gyollai, I., Fintor, K. and Szabo, M., 2021 - Origin of the Urucum iron formations (Neoproterozoic, Brazil): Textural and mineralogical evidence (Mato Grosso do Sul - Brazil); Ore Geology Reviews, v.139, 25p. doi.org/10.1016/j.oregeorev.2021.104456.
Silva, M.F., Dantas, E.L. and Vidotti, R.M., 2021 - Shortening history of the Neoproterozoic oroclinal bending in Paraguay belt, Central Brazil, based on structural interpretation of field work and resolution aerogeophysical data; Journal of South American Earth Sciences, v.107, 20p. doi.org/10.1016/j.jsames.2020.103043.
Silva, L.J.H.D.-R., Walde, D.H.-G. and Saldanha, D.O., 2016 - The Neoproterozoic-Cambrian Paraguay Belt, central Brazil: Part I - New structural data and a new approach on the regional implications; Tectonophysics, v.676, pp. 20-41. doi.org/10.1016/j.tecto.2016.03.019.
Tohver, E., Trindade, R.I.F., Solum, J.G., Hall, C.M., Riccomini, C. and Nogueira, A.C., 2010 - Closing the Clymene ocean and bending a Brasiliano belt: Evidence for the Cambrian formation of Gondwana, southeast Amazon craton; Geology, v.38 (3), pp. 267-270. doi: 10.1130/G30510.1.
Vasconcelos, B.R., Ruiz, A.S. and Matos, J.B., 2015 - Polyphase deformation and metamorphism of the Cuiabá group in the Poconé region (MT), Paraguay Fold and Thrust Belt: kinematic and tectonic implications; Brazilian Journal of Geology, v.45(1), pp. 51-63. doi:10.1590/23174889201500010004.

PARANÁ BASIN AND PARANÁPANEMA BLOCK

The Paraná Basin is a Palaeozoic to Late Mesozoic intracratonic basin that covers an area of close to 1.5 km² in southern Brazil, eastern Paraguay, northeastern Argentina and northern Uruguay, and hosts one of the largest igneous provinces of the world, the Cretaceous Serra Geral Formation. It spans the interval from ~660 Ma in the Ordovician to 66 Ma at the top of the Cretaceous, and laps onto the Amazonian, São Francisco and Rio Apa cratons. It is overlain to the west by the Cenozoic Pantanal Basin and is underlain by a thick Precambrian basement block, the Paranápanema Block. The latter is separated from the neighbouring cratonic elements by orogenic belts, specifically the Paraguaia and Brasilia fold belts to the west and NE respectively, and the Ribeira Belt to the SE. This basement block is also separated from the Amazonian and Rio Apa cratonic basement to the NW by the Transbrasiliano Lineament. The relationships between the Paranápanema Block and surrounding entities is discussed in the Goiás Magmatic Arc, Brasilia Belt and Paraguaia Fold Belt sections above.

The Paranápanema Block has been considered to be a fragment that separated from either the São Francisco craton during a Tonian rifting event (Fuck et al., 2008) or from the Central African/Congo Craton (D'Agrella-Filho and Cordani, 2017). It has been interpreted to comprises a Palaeoproterozoic Rhyacian and Statherian continental basement to the Paraná Basin and has the geophysical signature of a cratonic domain with a thin and stable continental crust, coupled to a thick underlying lithospheric keel (Cordani et al., 1984; Mantovani et al., 2001; Assumpção et al., 2006; Rocha et al., 2011). This interpretation has been reinforced by wide-angle reflection-refraction seismic transects (Bernardes, 2015; Peixoto, 2015; Affonso et al., 2021) which have revealed a thin upper, but a thick lower crust. Mid Mesoproterozoic Ectasian carbonate and clastic units reflect a passive continental margin along the northeastern to eastern margin of the Paranapanema Block (Pires, 1991; Campanha and Sadowski, 1999; Siga et al., 2011; Westin and Campos Neto, 2013), followed by the establishment of an active continental margin and magmatic arc along the entire northern and eastern edge of this continental block during the Neoproterozoic (Campos Neto and Caby, 2000; Campos Neto, 2000; Pimentel et al., 2000; Laux et al., 2005).
Deposition within the Paraná Basin reflects the influence of a long-lived stable basement where tectonic activity comprised gentle subsidence cycles and uplift producing transgressive-regressive marine cycles, with associated variations in climate and sediment supply, but no significant proximal orogenic activity (Sloss, 1990). However, it was influenced by the more distal Ordovician to Devonian Famatinian and Carboniferous to Triassic Gondwanan orogenic events on the margin of the supercontinent (Ramos, 1990).
The Paraná Basin sedimentary-magmatic succesion has a maximum total thickness of ~7000 m, and has been divided into six supersequences (Milani, 1997), as follows, from the base:
• Rio Ivaí Supersequence - which unconformably overlies the basement. It was deposited during the Ordovician and Silurian and represents a transgression and subsequent regression. It is made up of the lower Alto das Garças Formation basal quartzite and conglomerate, passing up into cross-bedded conglomeratic sandstones, with increasing reddish silt and clay towards the top. These are overlain by the Iapó Formation diamictites which have a silty-sandy matrix and varied clasts; and the uppermost Vila Maria Formation, composed of micaceous and ferruginous, but locally dark grey fossiliferous pelites that display hummocky cross-bedding and contraction desiccation cracks in their upper sections.
• Paraná Supersequence, or Paraná Group, which was deposited during the Devonian, and is up to 800 m thick, resting unconformably on both the Vila Maria Formation and basement. It is composed of the lower Furnas Formation, a succession of medium to coarse white quartz sandstones, with a high kaolinite content, various styles of cross stratification, and frequent conglomeratic beds up to 1 m thick. In its middle portion, medium grained sandstones predominate, intercalated with thinner siltstone and muscovite rich shale. At the top, medium to coarse sandstones with very thin layers of sandstone occur, with increasing mudstone interbeds and a gradational transition to the overlying Ponta Grossa Formation. This upper unit begins with ~100 m of shales containing fine sandstone lenses with stratification reworked by waves, and black laminated carbonaceous shale. The middle section is composed of alternating sandstone and siltstone, reflecting a progradation of deltaic systems. The upper part is predominantly a mudstone cap, representing large scale renewed flooding.
• Gondwana I Supersequence, which has a maximum thickness of ~2500 m and constitutes the largest sedimentary volume of the basin, was deposited between the late Carboniferous and the Early Triassic. It evolved from a glacial regime to a large, arid continental interior dominated by aeolian dune fields. The Karoo Ice Age, which had suppressed sedimentation, reached its apex during the Early Carboniferous, with deposition re-commencing at the onset of deglaciation during the Late Carboniferous Westphalian as the Itararé Group and Aquidauana Formation. These two units are composed of extensive glacial deposits, mainly sandstones, diamictites, conglomerates and muddy rocks. The deglaciation led to a sea level rise and the 'Permian transgression' (Lavina and Lopes, 1987). The succeeding Guatá Group, was composed of sedimentary strata with common reworked deltaic lobes and tidal regimes. It is divided into the Rio Bonito and overlying Palermo formations, which comprise two minor transgressive/regressive cycles. The Rio Bonito Formation is the dominant coal and carbonaceous shale bearing formation in the Paraná Basin. Coal seams are normally <0.5 m thick and laterally discontinuous, deposited in fluvial-deltaic and barrier-lagoonal depositional environments (Iannuzzi, 2010 and references cited therein). Where exploited the coal is bituminous to sub-bituminous. The overlying Passa Dois Group followed a large scale regressive trend and was dominated by continental deposition, with shallow silt facies giving way to a progradational complex of red beds, including deltaic lobes, lacustrine mudstones, aeolian and fluvial deposits. The succeeding Sanga Member of the Cabral Formation in the south and Pirambóia Formation in the north represent the advance of the continental systems over remnants of the Passa Dois Basin lacustrine facies. These formations are represented by fluvial and aeolian deposits that constitute a wedge that thins towards the SW of the basin.
• Gondwana II Supersequence, which developed in the Triassic and is marked by an abrupt change from sand to mud deposition across an unconformable surface, and is interpreted to indicate a rapid episode of subsidence and development of a starved basin lacustrine setting. This marks the basal contact of the Middle to Upper Triassic Santa Maria Group that comprises the Gondwana II Supersequence. It is subdivided into four third-order sequences, from base to top: Pinheiros-Chiniquá, Santa Cruz, Candelária and Mata sequences (Zerfass et al., 2003; Horn et al., 2014). Each of these sequences begins with fluvial deposition in low sinuosity rivers that is overlain by aeolian and shallow lacustrine deposits. This stacking is interpreted as cyclic basin subsidence, induced by tectonic uplift of the source areas matched with climate (Milani et al., 1998; Zerfass et al., 2004). The Maria Group contains reptile and mammal fauna, that can be correlated with those of the African continent.
• Gondwana III Supersequence, which straddles the Jurassic-Cretaceous boundary and is extensively developed across the basin. It is dominantly represented by the aeolian sedimentary Botucatu Formation and magmatic Serra Geral Formation. The Botucatu Formation covers an area of >1.3 million km² and represents a period of widespread desertification that occurred over sections of Gondwana prior to its Mesozoic breakup. Correlatives are recognised in the upper sections of Karoo System in southern Africa. The Botucatu Formation overlies a regional unconformity that extends throughout the entire basin (e.g., Milani et al., 1999). It is composed of aeolian sandstones that display large scale cross bedding with grain sizes that vary from fine to medium, with lesser coarse facies. The unit varies from a <10 to >400 m in thickness and is preserved by the overlying Serra Geral Formation basaltic flood lavas that were extruded while the dune fields were still active. The Serra Geral volcanic package is up to 2000 m thick and covers an area of ~1.2 million km², or ~75% of the Paraná Basin, and was intruded by an associated network of dykes and sills. It is estimated to comprise ~1 million km³ of lava, which was ~90 vol.% basalt, ~7 vol.% intermediate and ~3% vol.% felsic. This magmatism, dated at ~132 Ma (Ar/Ar; Renne 1992; Turner et al.,1994) accompanied a very active rifting and structural rearrangement of the continental crust of the Paraná Basin basement during the Early Cretaceous, coinciding with the onset of the separation of Africa and South America (Scherer, 2000).
• Bauru Supersequence, see the Bauru Sub-basin section below.

Paraná Basin and Paranápanema Block References
Affonso, G.M.P.C., Rocha, M.P., Costa, I.S.L., Assumpção, M., Fuck, R.A., Albuquerque, D.F., Portner D.E., Rodríguez, E.E. and Beck, S.L., 2021 - Lithospheric architecture of the Paranapanema Block and adjacent nuclei using multiple-frequency P-wave seismic tomography; Journal of Geophysical Research: Solid Earth, 19p. doi.org/10.1029/2020JB021183.
Curto, J.B., Vidotti, R.M., Fuck, R.A., Blakely, R.J., Alvarenga, C.J.S. and Dantas, E.L., 2013 - Unveiling the Transbrasiliano fault system in northern Paraná Basin using airborne magnetic data; 13th International Congress of the Brazilian Geophysical Society, Rio de Janeiro, Brazil, August 26-29, 2013, 5p.
Frugis, G.L., Campos Neto, M.C. and Lima, R.B., 2018 - Eastern Paranapanema and southern São Francisco orogenic margins: Records of enduring Neoproterozoic oceanic convergence and collision in the southern Brasilia Orogen; Precambrian Research, v.308, pp. 35-57.
Schultz, C.L., Martinelli, A.G., Soares, M.B., Pinheiro, F.L., Kerber, L., Horn, B.L.D., Pretto, F.A., Muller, R.T. and Melo, T.P., 2020 - Triassic faunal successions of the Paraná Basin, southern Brazil; Journal of South American Earth Sciences, v.104, doi.org/10.1016/j.jsames.2020.102846.
Westin, A. and Campos Neto, M.C., 2013 - Provenance and tectonic setting of the external nappe of the Southern Brasília Orogen; Journal of South American Earth Sciences, v.48, pp. 220-239.

SÃO FRANCISCANA (URUCUIA and ABATETÁ Sub-basins), BAURU and PARECIS BASINS

The São Franciscana, Bauru and the upper sections of the Parecis basins are three temporally equivalent cratonic basins deposited during a period of extension related to the progressive opening of the South Atlantic Ocean, and are spatially separated by Cretaceous uplifts (Fig. 1). The São Franciscana Basin overlies the São Francisco Craton to the NE, and is composed of the Urucuia Sub-basin in the north, and the dismembered remnants of its southern extension, the Abaeté Sub-basin, the result of uplift and erosion. It is separated from the Bauru Basin to the south by the NW-SE trending Alto Paranaíba Arch, and from the Parecis Basin to the west by the Gloias Massif. Both of these structural features expose Meso- to Neoproterozoic successions. The Bauru Basin is, in effect, an upper sub-basin of the much more extensive Paraná Basin, and is separated from the Parecis Basin to the NW by the Rondonópolis Uplift. The latter exposes Neoproterozoic basement of the Paraguaia Belt. The Parecis Basin to the NW overlies the northwestern margin of the Paraguaia Belt which encroaches onto the Amazonian Basin, and extends further to the NW to directly overlie the latter.

São Franciscana Basin
The base of the sequence in this basin commences with the Permo-Carboniferous Santa Fé Group, which unconformably overlies the Neoproterozoic the Cambrian Bambuí Group. The Santa Fé Group is composed of an up to 180 m thick package of diamictites, dropstone-bearing shales, sandstones and subordinated varvites and tillites of glaciolacustrine, glacio-fluvial and periglacial origin (Campos and Dardenne 1997). The exposure of these sedimentary rocks is scarce and limited to the central and northwestern portions of the basin, where they fill large valleys carved into upper Bambuí Group strata, often sitting on striated pavements. They are interpreted to reflect the Permo-Carboniferous glaciation that has affected West Gondwana (Sgarbi et al., 2001; Limarino et al., 2014; Torsvik and Cocks 2013; Vesely and Assine 2006; Reis, et al., 2017).
The unconformably overlying Lower Cretaceous Areado Group is an up to ~300 m thick arenite-dominated succession, mainly exposed in the southwestern section of the basin (e.g., Campos and Dardenne 1997; Sgarbi et al., 2001; Kattah 1991; Fragoso 2011; Pedrosa-Soares and Alkmim 2011). The succession largely represents a semi-arid and arid rift regime filling the Abaeté graben, overlain by aeolian sediments, which could be associated with either a late flexural post-rift stage or another, unrelated Upper Cretaceous subsidence phase. It has been divided, from the base, into the:
- Abaeté Formation, which comprises a medium- to coarse-grained alluvial sedimentary successions, locally containing interbedded sandstones and mudstone layers.
- Quirinó Formation, which is composed of discontinuous lacustrine strata that encompasses distal fine-grained siliciclastic sediments associated with turbidite deposits and thinner black shale layers (Kattah 1991; Sgarbi et al., 2001; Fragoso 2011). It contains plant fragments and fresh water fossils that are common throughout the succession (Sgarbi 2000; Sgarbi et al., 2001).
- Três Barras Formation, composed of fluvial and fluvio-deltaic sandstones, as well as widespread and thicker aeolian strata. It also contains restricted thin layers of silexite with bathyal/abyssal radiolarian fauna which afford a strong contrast to the overall continental setting of the Areado Group (e.g. Kattah 1991; Sgarbi 2000; Sgarbi et al., 2001; Arai 2009; Fragoso 2011).
The Upper Cretaceous Mata da Corda Group is exposed in the southwestern part of both the Abaeté and Urucuia Sub-basins, and comprises a succession of alkaline volcanic/sub-volcanic, volcaniclastic and epiclastic rocks (Campos and Dardenne 1997; Sgarbi et al., 2001; Sgarbi 2011). It is related to an episode of alkaline-carbonatitic phosphoritic igneous intrusions and a system of NW-trending dykes and kimberlitic and kamafugitic plugs that cut extensive areas of southeastern and central Brazil (Borges and Drews 2001; Silva 2006; Grasso 2010). This magmatism is generally associated with a late uplift event of the Cretaceous Alto Paranaíba Arch (Figs. 1 and 2; Hasui and Haraliy 1991; Sgarbi et al., 2001; Sgarbi 2011).
To the south, the group is composed of the <20 m thick basal Patos Formation pyroclastic breccias, tuffs and lacustrine silitites, overlain by the ~65 m thick Capacete Formation. The latter includes basal, up to 20 m thick, pyroclastic breccia and polymictic conglomerates, overlain by a thin cross-bedded conglomeratic sandstone and a succession of clay and lithic tuffs that are ~45 m thick (Karfunkel et al., (2015).
The Upper Cretaceous Urucuia Group covers an extensive area along the central and northern sections of the basin (Campos and Dardenne 1997; Sgarbi et al., 2001), and consists of up to 360 m of aeolian sandstones, locally associated with fluvial fine- to coarse-grained sediments. These deposits extend further to the north, where they overlie the Lower Cretaceous units of the Parnaíba basin (Campos and Dardenne 1997; Sgarbi et al., 2001). This group may be an equivalent to of the Mata da Corda Group rather than an overlying unit (Sgarbi et al., 2001).
The Areado, Mata da Corda and Urucuia groups are interpreted as continental interior manifestations of the Cretaceous rifting event that led to the opening of the South Atlantic Ocean (e.g., Hasui and Haralyi 1991; Sgarbi et al., 2001; Mohriak and Leroy 2012).

Alto Paranaíba Igneous Province
The Alto Paranaíba Igneous Province, follows the NW-SE elongated Alto Paranaíba Arch which separates the Abaeté Sub-basin of the São Franciscana Basin to the NE, from the Bauru Sub-basin of the Paraná Basin to the SW. It is characterised by Cretaceous magmatism related to the uplift of the arch, which commenced in the Lower Cretaceous and reached its peak in the Upper Cretaceous (Leonardos and Meyer, 1991; Campos and Dardenne, 1997). It also lies along the continental scale, 125° trending AZ 125 Lineament. The uplift and the faults of the lineament influenced the stratigraphy and facies distribution of both basins. This magmatism was predominantly between 90 and 80 Ma, and is represented by near 1000 ultrapotassic to potassic, ultramafic to mafic, silica-undersaturated lavas and hypabyssal intrusions, occurring as kimberlite, lamproite, lamprophyre, carbonatite and kamafugite (an ultrapotassic alkaline ultramafic rock; which predominates). The latter is the most extensive of this type in the world (Gibson et al., 1995; Araújo, 2000). Overall, the magmatic event comprised: i). 100 to 80 Ma kimberlites (with a few as old as 120 Ma), ii). 90 to 75 Ma kamafugites and iii). 91 to 71 Ma alkaline-carbonatitic complexes. Whilst these magmatic rocks were intruded into the arch, they also occurs as equivalent kamafugite lavas and volcanoclastic, pyroclastic and epiclastic tuff horizons which extend into the Mata da Corda Group, particularly the Capacete Formation, and contain xenoliths of plutonic rocks such as dunite, pyroxenite, melilitite and syenite. While these lavas and volcano-sedimentary facies are well developed within the São Franciscana Basin, they are less so in the Bauru Sub-basin where sedimentary units are only described as being rich in fragments of volcanic rocks derived from the Alto Paranaíba Arch. See also the separate Diamond Districts and kimberlites of the Atlantic Shield record.
The principal alkaline-carbonatite complexes within the arch and igneous province includes the Araxá, Tapira and Salitre I and II and Rocinha; complexes in Minas Gerais, and Catalão I and II in Goiás (Fig. 2).

Bauru Sub-basin
The Bauru Sub-basin, which is to the south of the Alto Paranaíba Arch, was filled by the Bauru Supersequence, deposited during the Aptian to Maastrichtian and is ~300 m thick. The basal unit of this supersequence, the Caiuá Group consists of well-sorted and well-rounded sandstones, with large-scale cross-bedded sets. The cross-beds commonly have coarse layers with reverse and normal grading, alternating with finer beds. Fining-upward cycles are also present, with intraformational conglomerates, fine to medium sandstones with cross-stratification or ripples, and mudstone layers. These deposits have been interpreted as predominantly aeolian (Soares et al., 1980) with fluvial components (Paula e Silva et al., 2005, 2009). A number of other interdigitating units with similar lithologies are interpreted to be lateral equivalents of, or to overlie the Caiuá Formation (Menegazzo et al., 2016).
The overlying Bauru Group was deposited in a semi-arid environment of alluvial fans and sand sheets crossed by ephemeral fluvial systems flowing into the desert. It is composed of a number of units, including the lower Adamantina Formation, which is characterised as fine sandstones with ripple cross-lamination or planar-to trough-cross stratification, and intraclasts of mudstones at the base of the troughs, interbedded with heterolithic facies, mudstones with mudcracks and matrix-supported intraformational conglomerates. This unit is interpreted to represent a meandering fluvial depositional environment (Soares et al., 1980; Paula e Silva et al., 2009). These are overlain by the São José do Rio Preto Formation composed of very fine- to medium-grained sandstones with planar-to trough-cross stratification, ripple cross-lamination and cross-bedded intraformational conglomerates, which are massive or show grading of clasts and/or matrix. The succeeding Uberaba Formation is lithologically similar, but differs in it's compositional immaturity and colour, being rich in fragments of volcanic rocks from the Paranaiba High, and it is associated with a braided fluvial depositional environment. The overlying Marília Formation consists of fining-upward cycles that include matrix-supported conglomerates with intra- and extra-formational clasts, fine to very coarse cross-bedded sandstones and rare mudstones. Calcrete structures are common with abundant carbonate nodules. The Itaqueri Formation is very similar, but has less carbonate cement, and has layers with silica cementation. The Marília and Itaqueri formations are interpreted as alluvial fan deposits (Mezzalira, 1974; Soares et al., 1980; Riccomini, 1997a; Ladeira and Santos, 2005).
The Bauru Sub-basin is an equivalent of the sequence in the São Franciscana basin to the north across the Alto Paranaíba Arch, and the Perecis Basin across the arcuate arch of exposed Paraguaia Fold Belt rocks to the NW and west. The sequence within the sub-basin is interpreted to have been deposited in a flexural depression that resulted from the underlying Serra Geral Formation basaltic flood lava pile load.

Parecis Basin
The Late Ordovician to Late Cretaceous Parecis Basin overlies the Amazonian Craton, the Tonian to Cryogenian external zone of the Neoproterozoic Paraguaia Orogen sequence, and the Cryogenian to Ordovician intracratonic Araras-Paraguay Basin. As such, its southeastern edge straddles the onlapping northwestern margin of the Paraguaia Orogen sequence of the Atlantic Shield, onto the Amazonian Craton (Fig. 1).
The Paraguay Belt was deformed and imbricated in a transpressional ductile tectonic regime to form the metamorphosed rocks of the Cuiabá Group during the Neoproterozoic Braziliano-Pan African Orogeny (Almeida and Mantovani 1975; Siqueira and Teixeira 1993; Pedreira and Bahia 2000; Cordani et al., 2000; Cordani et al., 2013; Santos 2006; Nogueira et al., 2019).
The Araras-Alto Paraguay Basin, which lies over the southeastern Amazonian Craton, was inverted during the Ordovician, and deformed in the Cretaceous by brittle to brittle-ductile transtensional tectonics (Cordani et al., 2000; 2013; Santos 2016; Nogueira et al., 2019). It was filled by the:
- Late Cryogenian Puga Formation glaciogenic diamictite, siltstone and sandstone;
- Ediacaran Araras Group limestone, dolostone and subordinate siliciclastic rocks; and
- Cambrian to Ordovician Alto Paraguay Group sandstone and pelite.
The 1200 x 400 km, ENE-WSW elongated, Parecis Basin, which covers an area of ~0.5 million km² is a rift-sag basin, initially formed over the Amazonian Craton during an extensional event related to the Rodinia breakup between 1.0 and 0.75 Ga (Pedreira and Bahia 2000; Teixeira 2001), but was affected by another extensional pulse during the Late Ordovician, generating intracontinental rift systems through basement fault reactivation (Cordani et al., 2000). It embraces an up to 6000 m thick Palaeozoic and Mesozoic sedimentary-magmatic sequence, with a hiatus between the Late Carboniferous and Lower Jurassic. It is intruded by Cretaceous mafic and ultramafic rocks, and overlain by Cenozoic sediments (Siqueira 1989; Siqueira and Teixeira 1993; Bahia et al., 2006; Bahia 2007). The succession has been subdivided as follows (Rezende et al., 2021 after Bahia et al., 2006; Lopes Afonso et al., 2017):
- Late Ordovician to Silurian Pimenta Bueno Formation diamictite, sandstone, siltstone and pelite, interpreted as glacial-marine and tide- to storm-influenced platform deposits, representing a glacio-eustatic regressive-transgressive event (Afonso 2016). This unit has a limited distribution, overlying Proterozoic basement and filling the restricted Pimenta Bueno graben. The formation is ~760 m thick (Siqueira, 1989).
- Early Devonian Furnas Formation, which is exposed in the southeastern corner of the Parecis Basin, but also occurs within the Paraná Basin. It begins with plane-parallel bedded conglomeratic sandstone, with angular to sub-rounded pebbles of >5 cm diameter. Where measured, it is ~11 m thick and lies between crystalline basement and the gradationally overlying Ponta Grossa Formation. It is interpreted to have been deposited in a fluvial, or shallow marine to tidal flat regime (Ciguel et al.,1996).
- Devonian Ponta Grossa Formation, which also outcrops in the southeastern section of the Precis Basin, and within the neighbouring Paran&aacure; Basin. Where exposed, it comprises intercalated black and yellow layered siltstone and very fine sandstone, separated by lateritised bands, defining a plane-parallel stratification or plunging 5° to the north. The top of the formation is a 10 m thick brown shale. To the SW, it consists of finely laminated green shales, fine and coarse sandstones, with cross bedding, and locally conglomeratic sandstone. The unit has been measured at ~40 m thick, and in the Paraná basin represents a shallow marine environment, transiting to a deeper environment, as indicated by the deposition of pelites in the upper part of the sequence (Oliveira, 1912).
- Lower Carboniferous to Lower Permian Fazenda da Casa Branca Formation, which is largely restricted to the margins of the Parecis Basin. Padilha et al. (1974) and Ribeiro Filho et al. (1975) mapped conglomerates, arkoses, greywacks and pelites in the south of the basin, whilst Costa et al. (1975) recognised the formation on the eastern edge of the basin, where it comprises conglomerates, sandstone and silty sandstone with dropstones, deposited over the Ponta Grossa Formation. It is also found on the northern and western edges of the basin. To the north, it is a brown, very fine, clayey, massive sandstone, passing up into massive, coarse feldspathic sandstone of the same colour, with quartz and granite pebbles up to 5 cm in diameter, followed by more fine sandstone. In the western edge of the basin it is typically represented by a cream-coloured fine, clayey sandstone, with a regular north dip (Leal et al., 1978). In the centre of the basin, the succession has a maximum 150 m thickness, but thins to ~40 m. The conglomerates on all four margins have clasts with a maximum diameter of 40 cm. The unit is variously interpreted to represent a fluvio-lacustrian setting on a wide floodplain (Padilha et al., 1974) to glacial or periglacial (Siqueira 1989; Caputo 1984). The base of the unit commonly overlies the Pimenta Bueno Formation, whilst the upper contact is erosive, marking the beginning of the hiatus that persisted until the Jurassic (Bahia et al., 2006).
- Lower Jurassic Anarí and Tapirapuã formations, comprising isotropic basalts, with fine to aphanitic granulation, lead-grey colour and columnar jointing. Those of these basalts that have been dated have ages of 200 to 197 ±6 M and occur as lava flows, but also have associated extensive networks of sills and dykes hosted in Neoproterozoic and Palaeozoic rocks. This magmatism is interpreted to be related to the opening of the Central Atlantic Ocean, which preceded the Serra Geral Formation (the 'Paraná Basalts') of the Paraná Basin, at ~134 Ma, referred to as the Paraná-Etendenka magmatism, which was related to the opening of the South Atlantic (Mizusaki et al., 2002; Baski and Archibald, 1997).
- Late Jurassic to Lower Cretaceous Rio Ávila Formation, well- to poorly-sorted, friable, cross-bedded red sandstone, with rounded grains, cut by intrusions of dolerite and lamprophyres. It is ~90 m thick, and interpreted to be of aeolian origin (Siqueira, 1989). Cuneiform cross bedding structures, are locally as thick as 20 m (Ribeiro Filho et al., 1975).
Cretaceous Parecis Group, divided into:
- Salto das Nuvens Formation, principally an aeolian sequence, composed of bimodal, fine- to medium-sandstone, with intercalations of claystone and conglomerate, and common wedge-like cross bedding sets up to a metre high and tens of metres in length (Barros and Pastore Jr., 1974). It directly overlies the aeolian sandstones of the Rio Ávila Formation, whilst the uppermost layers are silicified sandstones to orthoquartzite with intercalated silty sandstone layers. The basal conglomerates in the southwest of the basin are polymictic and poorly sorted, with clasts of gneiss, quartzite, sandstone, shale and slate (Barros and Pastore Filho 1974). The unit contains Mid to Upper Cretaceous fauna.
- Utiariti Formation, which overlies the Salto das Nuvens Formation via a gradational contact, and marks the change from a predominantly aeolian to a sub-aqueous setting, but with significant aeolian sections. It comprises 120 to 150 m of white, pink, yellow and grey, fine- to medium-grained sandstone, essentially composed of quartz and feldspar, with silicified layers and preserved ripple marks (Padilha, 1974). The lower sections include basal conglomerates, while in the middle of the succession there are numerous conglomerate filled channels, while the upper parts suggests the presence of an area where interdune lakes are repeatedly filled by dune migration.
- Cretaceous kimberlites outcrop in clusters intruding both Neoproterozoic Paraguaia Orogen sequences on the Rondonópolis Uplift and sedimentary rocks of the Rio Ávila Formation to its north, and as high in the section as the Mid to Upper Cretaceous Utiariti Formation of the Parecis Group (see the Diamond Districts and kimberlites of the Atlantic Shield record). These kimberlites are part of the Paranatinga Diamond Province and have been dated at 126.3 to 122.6 Ma (U-Pb zircons; Heaman et al., 1998) and 121.1 to 120 Ma (Davis, 1977), although it is likely younger intrusions of Upper Cretaceous age are also present as in the neighbouring Alto Paranaíba Igneous Province. They are primary igneous kimberlites occurring as pipes with brecciated margins and caldera-type sediments, containing sandstone and crystalline basement xenoliths. None of these are diamondiferous, although other clusters further north in the Amazonian Craton are. These are external to the Atlantic Shield and not covered here.
Cenozoic Cover, which becomes thicker and more consolidated to the east to become the Alto Xingu Basin. It consists of sandy, silty and sand-silt sediments with local gravels, in addition to laterites (Schobbenhaus et al., 1981).

The most recent source geological information used to prepare this decription was dated: 2022.
This description is a summary from published sources, the chief of which are listed below.
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Porter GeoConsultancy Pty Ltd (PorterGeo) provides access to this database at no charge. It is largely based on scientific papers and reports in the public domain, and was current when the sources consulted were published. While PorterGeo endeavour to ensure the information was accurate at the time of compilation and subsequent updating, PorterGeo, its employees and servants: i). do not warrant, or make any representation regarding the use, or results of the use of the information contained herein as to its correctness, accuracy, currency, or otherwise; and ii). expressly disclaim all liability or responsibility to any person using the information or conclusions contained herein.

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