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Caraiba - Pilar, Jaguari, Surubim, Angicos, Vermelhos, R22W, Sucuarana |
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Bahia, Brazil |
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Cu
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Super Porphyry Cu and Au
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IOCG Deposits - 70 papers
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All papers now Open Access.
Available as Full Text for direct download or on request. |
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The Jaguarari or Caraiba group of Cu orebodies are located ~370 km NNW of Salvador in Bahai, Brazil (#Location: 9° 52' 2"S, 39° 52' 18"W).
The first documented occurrence of copper in the Curaçá Valley was located at Serra da Borracha, Curaçá County in 1782, although its potential was not recognised until investigated by the National Department for Mining Productions (DNPM) in 1944. Exploration and feasibility studies commenced in 1969, before being taken over by the National Bank of Economic and Social Development (BNDES). Caraíbas Metals S/Apen commenced the Céu Aberto open pit operations at Cariaiba in 1979, followed by the initiation of underground mining in 1986. Privatisation was complete by 1994, and the operating company became Caraíba Mining S.A. In 2010, the mining of the Surubim deposit, 33 km to the NNE of Caraíba began, and in 2013, production at the Angico deposit, 42 km NNE of Caraíba commenced operations.
In 2017, the active operations included the Caraíba Mine (comprising the underground Pilar Mine, integrated Caraíba Mill and the inactive solvent extraction electrowinning plant), the open pit Surubim Mine and the underground Vermelhos Mine which is ~60 km north of Caraíba, was under construction. Past producing operations included the historic open pit mines of R22W and the Angicos. The Suçuarana mine, ~15 km south of Caraíba, was nearing the end of its mine life.
Regional Setting
The Caraiba deposit is situated on the northern margin of the São Francisco Craton craton, within the Curaçá high-grade granulite facies granite gneiss terrane that hosts numerous sill-like mafic-ultramafic intrusive bodies. This gneiss terrane is part of the Salvador-Curaçá orogen, which is, in turn, the northern extension of the north-south trending Atlantic Coast granulite belt (Mascarenhas et al., 1984; Oliveira and Tarney, 1995) that has been interpreted as a continental magmatic arc (Figueiredo, 1980) of Neoarchaean age (2.4 Ga, Barbosa, 1990) cutting across the craton, separating the Serrinha and Mairi Archaean blocks to the east and west respectively (Barbosa, et al., 1996, Barbosa, 1996).
The Serrinha Block is composed of Archaean gneisses and migmatites, Cr-bearing mafic-ultramafic bodies, Palaeoproterozoic greenstone sequences and granites. The Itiúba syenite, which separates the Curaçá gneiss terrane and Serrinha Block, was intruded, deformed and metamorphosed at amphibolite facies conditions, at ~2.0 Ga (Rb-Sr; Figueiredo, 1976; Conceiçáo, 1990).
The Mairi Block, to the west, comprises Archaean gneisses and migmatites, cut by a major Cr-bearing mafic-ultramafic intrusion that is unconformably overlain by Palaeoproterozoic metasedimentary and volcanic rocks of the Jacobina Group, all intruded by a Meso- to Palaeoproterozoic granite (Inda and Barbosa, 1978; Silva, 1996).
The country rocks of the Curaçá gneiss terrane are interpreted to comprise a metamorphosed supracrustal sequence, now represented by banded gneisses, graphitic gneiss, banded iron formation, calc-silicates and alumina rich gneiss, and biotite-hornblende-bearing quartz-feldspar gneiss, with minor amphibolites and quartzites (Sá et al., 1982; Hasui et al., 1982; Sá and Reinhardt, 1984; Silva, 1985).
These supracrustal rocks were subjected to three principal phases of deformation with associated granitic intrusion, metamorphism and migmatisation:
• D1 is characterised by tight isoclinal folding, dated at 2328 Ma (Silva, 1985), which produced the gneissic banding, and was accompanied by tonalitic orthogneiss intrusion (G1), migmatisation and amphibolite facies metamorphism. F1 folds are generally of ~10 cm-scale, rootless and intrafolial relative to SI.
• D2 is characterised by tight isoclinal folding with east-west axes, followed by the intrusion of a second generation of tonalites (G2), mafic dykes and eventually granulite facies metamorphism (at 5.5 to 6.5 kbar and 750 to 720°C; Ackerman et al., 1987). Individual F2 folds (and S2) are not readily distinguished, except in more felsic lithotypes, where F2 folds with east-west trending, sub-vertical to sub-horizontal axes, interference folding of F1 folds, and an east-west trending S2 mineral foliation of biotite and orthopyroxene are evident.
• D3 resulted in tight, cm- up to km-scale, non-cylindrical folds with north-south axial planes that dip at 70 to 75°W and plunge either northerly or southerly. S3 is a penetrative mineral foliation across the entire terrane, defined by biotite, hornblende and strongly flattened quartz and feldspars. Non-mica minerals define a penetrative L3 mineral stretching lineation parallel to the axial planes. D3 was accompanied by granitoid sheets (G3) and amphibolite to granulite facies metamorphism (Sá et al., 1982; Silva, 1985) and may represent the Transamazonian cycle (2050 Ma; Silva, 1985). The G3 granitoids occur as a swarm of north-south trending dykes of reddish pink alkaline granites that are tens of centimetres to tens of metres in thickness, persist over strike lengths of kilometres, and are emplaced parallel to and commonly displaying S3 foliation. They cross-cut F3 hinge-lines, and overprint all older rocks, including the mineralised orthopyroxenites that host the ore deposits.
Northward from ~20 km to the south of Caraiba, nearly three hundred mafic-ultramafic bodies intrude the Curaçá gneiss terrane. Those that are Cu-bearing are magnetite orthopyroxenite (hypersthenites) and/or diorites (locally called norites), whilst the vast majority, which are Cu-poor or barren, are gabbros, gabbronorites and anorthosites (Lindenmayer, 1981).
The relationships between the different mafic to ultramafic bodies within the terrane is not certain. They may represent individual intrusions localised in the crests of small anticlinal folds, or possibly form part of a single, tectonically disrupted, thrust sheet controlled intrusion, based on the similarity in composition between the orthopyroxenites from several localities distributed over an 80 km of strike (Maier and Barnes, 1996).
The mafic-ultramafic bodies are apparently broadly conformable with the D1 tonalitic and granitic orthogneisses dated at 2328 to 2050 Ma (U/Pb, Silva, 1985), and are interpreted to have been intensely folded by all of the three main phases of deformation described below, and hence older than D1 (Silva, 1985; D'el Rey Silva et al., 1994). However, Oliveira and Tamey (1995) dated the orthopyroxenites at 1890±60 Ma (Sm/Nd) and noted the occurrence of apophyses of orthopyroxenite and massive sulphide ore cutting foliation and lithological boundaries within the country rock. Maier and Barnes (1999) suggest this may be explained by differences in competency during folding and remobilisation of sulphides during high temperature deformation.
The geology of the Curaçá gneiss terrane, as described above, represent three main rock groupings, namely, i). the metamorphosed supracrustal sequence, ii). the mafic-ultramafic intrusive suite, and iii). the migmatitic gneisses and syn-tectonic granitoid intrusions (Gl and G2) of grey tonalites and granodiorites (Jardim de Sá et al., 1982). Apart from G2, which are far more numerous than Gl around Caraiba, most of the rocks above are overprinted by an amphibolite-facies regional metamorphic banding (S1) that commonly encloses sub-parallel, 1 to 10 mm, up to 1 m thick, sheet-like layers of quartz and feldspar or simply feldspar that are highly deformed and suggest syn-D1 migmatisation (D'el Rey Silva et al., 1999).
Deposit Geology, Structure and Mineralisation at Caraíba
At the surface, the mineralised orthopyroxenite has an irregular amoeboid shape, with a strike length of ~1750 m, distributed over an area with north-south dimensions of ~1200 m, and width of ~500 m. It comprises a central, contorted, 500 m long, east-west oriented section where the mineralised layers dip at ~70°to the N, with two north-south arms one curving north from the western extremity of the central zone. This arm splits into two layers that dip at ~80° generally to the W. These layers stretch continuously northwards, although the easternmost plunges to the north and is only continuous below the surface. The second north-south arm occurs as two layers that form a narrow corridor juxtaposed to the south of the inner parts of the central zone (D'el Rey Silva et al., 1999).
In detail the ore deposit represents a tight, asymmetric, F2 synform-antiform pair, with steep south dipping, east-west trending axial planes, that have been refolded by an F3 fold with an upright, north-south trending axial plane, and shallowly south plunging axis. The east-west central section of the exposed deposit represents the steep, contorted southern limb of the tight F2 synform and adjacent antiform. The northern arm is the western limb of the F3 synform folding the gently dipping northern limb of the F2 synform, although the eastern F3 limb is absent where the orebody has lensed out below the surface. The southern arms of the deposit are the F3 folded dislocated, gently south dipping southern limb of the F2 antiform. This composite structure resembles a north-south trending conical mushroom lying on its side, sliced from the crest to the base of the stem by the current surface. The deepest limit of the mineralised orthopyroxenite is at the intersection of the F2 and F3 synforms in the central zone, where it reaches depths of ~1600 m (D'el Rey Silva et al., 1999).
The Cu sulphide mineralisation is almost exclusively hosted by orthopyroxenites, although elevated Cu sulphide levels also occur in small diorites (to ~0.4% Cu) and glimmerites (to ~1.9% Cu), as well as some calc-silicate gneisses and felsic breccias directly adjacent to the orthopyroxenites. Other lithologies are generally barren. Gabbronorites not directly associated with the pyroxenites and those in the hanging-wall sequence of the Caraiba orthopyroxenite sill, may contain up to 3 percent sulphides as pyrite and pyrrhotite but are generally Cu poor (Maier and Barnes, 1999).
The mineralised orthopyroxenite is closely associated with a set of Cu-barren gabbros, gabbronorites and anorthosites, but is also found in contact with barren supracrustal rocks (mostly gneisses) to the west, and with a sequence of well-banded mafic gneisses to the east. The contacts with the barren mafic intrusives and mafic gneisses is generally gradational, marked by increasing amounts of layer-parallel feldspathic bands. The contact with the gneisses on both sides is generally subvertical and commonly marked by zones of intense migmatisation and partially overprinted by late NNW and NNE trending zones of ductile shearing. Chalcopyrite and bomite were remobilised into small shear zone-controlled veins, even within the main orebody and into adjacent rocks.
The average orthopyroxenite contains ~60 to 70 vol.% orthopyroxene, <5 vol.% andesine plagioclase, 5 to 10 vol.% Cu sulphides and oxides each, and 5 vol.% red phlogopite (which may rarely be >50% to form a glimmerite). The diorites (known as norites in local literature) mainly contain andesine plagioclase (>50 vol.%), orthopyroxene (5 to 50 vol.%), quartz (5 to 20 vol.%) and phlogopite (5 to 50 vol.%). Apatite and zircon are common accessories in the orthopyroxenites, diorites and glimmerites (Maier and Barnes, 1999).
According to Maier and Barnes (1999), there is abundant evidence that the orthopyroxenites, diorites and glimmerites have undergone high-grade metamorphism, on the basis of their deformation (particularly the micas), fracturing (well developed in some zircons), undulous extinction (in orthopyroxene, plagioclase, quartz, plagioclase, and mica), granular textures with tripple point junctions, and subgrain walls. D'el Rey Silva et al. (1999) observe that the Cu-bearing rocks have a clear S1 metamorphic banding, generally sub-vertical either near the contact or within the richest parts of the orebody itself, particularly within melanorites that contain <1 to > 10 cm thick layers of (hypersthene) orthopyroxenite interbanded with norites and leuconorites. Both the orebody contact and S1 are folded by 0.1 to 10 m size F3 folds, the hinges of which are invaded by <1 to > 10 cm thick, late folding feldspathic (and quartz) melts, and locally by G3 granites. S2 foliation is rarely seen in the main deposit, although F2 folds with E-W trending, sub-vertical to sub-horizontal axes, F2-F3 interference folds, and an E-W trending S2 biotite and orthopyroxene mineral foliation, are evident in surrounding felsic wall rocks. S3 is penetrative in both the mineralised mafic-ultramafic rocks and wallrock gneisses, which display abundant F3 folds with generally southerly and gently plunging axes. Apart from narrow chlorite-epidote-sericite-carbonate rims around microscopic to macroscopic fractures and veinlets, the orthopyroxenites show little retrograde alteration accompanying this metamorphism.
The sulphide assemblage in the orthopyroxenites is almost exclusively of bornite and chalcopyrite, which commonly show symplectitic intergrowth, and on average, occur in approximately equal proportions (Maier and Bames, 1996), although locally relative compositions are very variable. There is also some variation between individual bodies within the district, from bornite to chalcopyrite dominant intrusions (Maier and Barnes, 1999).
Many of the orthopyroxenites, diorites and glimmerites are highly enriched in light REE (most likely contained in apatite and zircon), in contrast to the other mafic-ultramafic rocks elsewhere in the terrane (Maier and Barnes, 1999).
The majority of the orthopyroxenite- (and diorite-) hosted ore is disseminated, occurring as anhedral sulphides interstitial to the silicates. Locally, the disseminated ore grades into massive aggregates, pods, and schlieren of sulphides that may reach a few tens of cm in thickness, and are composed of the same sulphide assemblage as the disseminated ores.
Within the Caraiba deposit, massive sulphides tend to be concentrated in synclinal closures, indicating local syn-kinematic remobilisation. Microscopic and macroscopic veins of sulphides, replacement of oxides by sulphides (Maier and Barnes, 1996), and finely dispersed sulphides in fractures and cleavage planes of silicates indicate local remobilisation of the ore in all orthopyroxenite bodies in the Curaçá gneiss terrane (Maier and Barnes, 1999). However, remobilisation has not generally mineralised the country rocks, except for occasional sulphide veins of up to 20 cm in thickness transgressing the hanging-wall rocks, and local mineralisation of some calc-silicate gneisses.
Oxides, which comprise up to 50% of the mineralised orthopyroxenite, are mainly titanomagnetite and ilmenite, with lesser pure magnetite and rare chromite, occurring as euhedral or anhedral disseminated grains interstitial to silicates, as massive aggregates, and in veins and veinlets where they may or may not be associated with sulphides (both chalcopyrite and bornite). The magnetite contains up to 14 wt.% Cr203, 5.8 wt.% Al203, 2 wt.% V203, 1 wt.% ZnO, and 7 wt.% Ti02 (Maier and Barnes, 1996), and has particularly high Ti, AI and Zn contents, suggesting subsolidus equilibration with orthopyroxene (Maier and Barnes, 1996).
δ34S values fall into a mantle range of -1.495 to +0.643‰, although the εNd value of -4.3‰, from the Caraiba dyke (n=3) suggests the involvement of a crustal component in the geologic evolution of the bodies. It is still unclear whether this crustal signature represents a source characteristic or is the result of magmatic contamination, metasomatism, or mechanical hybridization of contrasting lithologies during the intense deformation of the rocks (Maier and Barnes, 1996).
Maier and Barnes (1999) regard the ore as highly atypical of magmatic deposits in that it contains up to 50% titanomagnetite and magnetite, the sulphide
assemblage comprises bornite and chalcopyrite (with an average Cu:Ni ratio of 40), and the host orthopyroxenites contain abundant phlogopite and locally, apatite and zircon. In addition, orthopyroxenites distributed over a strike length of ~80 km, contain between 100 and 500 ppb PGEs, although individual samples may contain as much as 2700 ppb. Mantle-normalised noble metal patterns are relatively fractionated, with Pd:Ir ratios of ~70. They therefore conclude, that as hydrothermal Cu sulphide ores typically show much more pronounced noble metal fractionation, caused by the relatively high mobility in low-temperature fluids of Au, Pd and Pt, compared to Os, Jr, Ru and Rh, the Caraiba deposits are likely originally of magmatic origin.
To explain the high Cu:Ni and other unusual features of the Curaçá gneiss terrane ores, Maier and Barnes (1999) suggest that the orthopyroxenites may represent restitites of a sulphide-, magnetite-, phlogopite- and apatite-bearing dioritic protolith which underwent anatexis and effective melt extraction. The sulphides may have been molten but could have remained in the restite due to their relatively high density. Partial dissolution of the sulphide melt by the S-undersaturated silicate melt would cause enrichment of the excess sulphide melt in the highly chalcophile Cu and Se, potentially followed by the crystallisation of bornite and chalcopyrite. This interpretation, they suggest, is supported by the absence of differentiated lithologies that may represent residual liquids and by the fact that the Curaçá gneiss terrane deposits are located in high-grade metamorphic terranes.
R22W Mine
The R22W Mine is located northwest of the Caraíba Mine. Mineralisation is hosted by differentiated mafic-ultramafic rocks that were intruded into granulite facies gneissic rocks. The norite and gabbro at R22W are generally non-economic, but occasionally host copper bearing zones. The gneissic rocks are well exposed in the northwestern wall of the open pit at Caraíba, where it occurs as a banded, undifferentiated, mafic gneiss composed of quartz-feldspar gneiss with interlayered amphibolite and calc-silicate rocks thought to be derived from basic-ultrabasic protoliths (D'el Rey et al., 1988). At a smaller scale, these rocks are migmatitic as observed in the southeast side of the open pit. The youngest rocks in the mine area are very fine-grained rose to grey, syn- to late-tectonic granite that occurs as elongated bodies aligned with the S3 regional foliation and can be observed in the western side of the Caraíba open pit. The mineralisation at the Caraíba and the R22W Mine are associated with a thickened portion of the mafic-ultramafic intrusion. Mineralised lenses dip steeply to the west and plunge steeply to the north. The mafic-ultramafic sequence is reportedly thickened along a D3 synform, interpreted to be a parasitic isoclinal fold developed on a larger scale D2 antiform and is interpreted as an interference structure, with an orthogonal north-south axis. Alternatively this may be a sheath fold. The mineralised zones thicken along the F3 axial plane, S3 foliations and D2/D3 fold interference. In addition, the mineralised zones may be disrupted and offset along F3 due to the D3 deformational event (From Mendonça et al., 2017).
The mineralisation at the Caraíba Mine is hosted by pyroxene hypersthenite, with the copper grade typically being directly proportional to hypersthene content and magnetite, and inversely proportional to plagioclase and clinopyroxene. Grades within the gabbro-norite, gabbro and anorthosite units tend to be un-economic. The copper sulphide zones at the Caraíba Mine are up to 20m thick. The dominant sulphides are chalcopyrite and bornite with accessory digenite, pyrrhotite, pentlandite, covellite, pyrite and cubanite. Magnetite dominates the oxide phases with minor ilmenite and chromite. Silicate minerals, are mainly orthopyroxene, plagioclase and phlogopite with minor amphibole, chlorite, epidote and late quartz.
The mineralisation within the 'Aprofundamento' (or 'Deep') zone at the Caraíba Mine extends from RL -400 to -1150 m levels and occurs as lenses that strike north-south and dip steeply to the east or west with a synformal geometry. The total known down-plunge length of that mineralisation iin 2017 was ~1600 m from the surface, with individual lenses averaging ~12m in thickness.
The R22W Mine mineralisation is the northern extension of the Caraíba Mine copper mineralisation, where it occurs as lenses striking to the north and dipping steeply to the west. The length of mineralisation is about 45 0m, with the lenses varying between 1 and 40 m in thickness, depending on depth (From Mendonça et al., 2017).
Surubim
Surubim is also located within Caraíba Complex of rocks have been subjected to granulite facies metamorphism. The principal lithologies in the deposit area are gneiss, basic and felsic granulite, and charnockite. Biotite and graphite bearing norite and gabbro are also found in the deposit area, and are the intrusive mafic to ultramafic assemblages that host mineralisation. These rocks are more biotite-rich than those at Caraíba. Four deformation events have been identified at Surubim. F1 and F2 folding are co-axial while F3 is perpendicular to the preceding two. D4 is characterised by brittle deformation and includes faults and fractures. F1 and F2 folds are similar, with north-south, vertical axial planes, and have amplitudes from 100 to 1000 m. F3 folding, which has produced gentle concentric folds with vertical axial planes, has resulted in F1 and F2 axial planes striking at between 40 and 320°. The five main D4 faults recognised in the Surubim area have produced little offset of the previous three deformation events. In the northern part of the Surubim area, mineralisation is confined to a synform structure with a north-south axial plane dipping 40°W and plunging gently to the north. The margins of the synform have parasitic folds that have an extent of 200 to 300 m, with thicknesses of about 50 m. At the southern end, the mineralisation is vertical and has a 'stretched S' shape. The mineralised zone has lateral extensions with thicknesses ranging from 40 to 150 m (From Mendonça et al., 2017).
Mineralisation within the Surubim open pit includes chalcopyrite and bornite as well as the copper-iron sulphide, idaite (Cu5FeS6), and lesser amounts of pyrrhotite and pentlandite.
Vermelhos
The Vermelhos area is almost totally concealed by quartz-rich colluvium with rare outcrops along streams. Host rocks to mineralisation comprise north-trending steeply-dipping norite, pyroxenites and melano-norite that were intruded into the host gneiss. Mineralisation occurs as sulphide in disseminated to semimassive and massive bodies and along fractures striking north and dipping steeply to the west. Most of the current tonnage is hosted by a semi-massive to massive tabular sulphide body that plunges north. Mineralisation includes chalcopyrite, bornite, pyrrhotite and pentlandite. Three mineralised zones have been defined: Vermelhos South, Vermelhos East and Vermelhos West. Only the Vermelhos South area was being considered for development in 2017 and comprised the Vermelhos UG Mine (From Mendonça et al., 2017).
NOTE: Hühn et al. (2020) suggest the copper deposits of the Curaçá Valley, including Caraiba, are members of the IOCG family of deposits on the basis of the presence of i). primary sulphides that include bornite and chalcopyrite; ii). large amounts (up to >50 wt.%) of magnetite; iii). a high Cu/Ni ratio of ~40; and iv). orthopyroxenites with abundant biotite related to shear zones.
The same authors also point out that the Caraíba orebody is mainly hosted in mafic-ultramafic complexes with hydrothermal calcic-ferric alteration being related to copper-ore zones. They also note that work shows early 2580 ±10 Ma (Oliveira, E.P., 2004) orthomagmatic mineralisation is overprinted by a later hydrothermal event that produced IOCG mineralisation at ~2 Ga (Teixeira, et al. 2010; Garcia, et al. 2018; Garcia, et al. 2013). Studies conducted by D'el-Rey et al. (2017) and D'el-Rey (1985) provide evidence of structural control at the Caraíba mine. The ore minerals at Caraíba, which include chalcopyrite, bornite and chalcocite are usually associated with magnetite. The primary (magmatic) mineralisation comprises intercumulus crystals of disseminated chalcopyrite, bornite and magnetite grown in the interstices of pyroxenes and amphiboles. Minerals associated with the subsequent hydrothermal alteration include biotite, microcline, epidote, chlorite, magnetite, and quartz (Garcia, 2013). Hühn et al. (2020) also note that ore often occurs as veining or as magnetite hydrothermal breccia, whilst magnetite sometimes occurs in equilibrium with spinel. Ilmenite is frequently replaced by chalcopyrite, bornite and magnetite, particularly when the host rock is a biotite mylonite. Magmatic ilmenite is replaced
by hydrothermal ilmenite. They also state that the IOCG system is richer in copper, is highly magnetic, and denser.
Resources and Production
Open pit mining was to a depth of 200 m with a waste:ore ratio of 4.5:1. Below this, ore is being mined underground to a depth of 850 m, with plans (in 2013) to extend to a total depth of 1600 m below the surface.
The deposit had pre-mining resources estimated to have been: 90 Mt @ 1.4% Cu -or- 135 Mt @ 1.1% Cu or 150 Mt @ 0.8% Cu -or- 96 Mt @ 1.82% Cu (latter from Teixeira et al., 2010).
Total production from the open pit and underground mining operations at Caraiba from 1978 up to 30 June, 1998 (D'el Rey Silva et al., 1999):
~60.5 Mt @ 1.6% Cu.
Remaining NI 43-101 compliant Mineral Resources as at 31 March 2017 (Ero Copper Corp. Technical Report, 2017) were:
Pilar underground mine
Measured+Indicated Resource - 17.2297 Mt @ 1.95% Cu;
Inferred Resource - 1.5139 Mt @ 2.45% Cu.
Vermelhos underground mine
Measured+Indicated Resource - 2.5414 Mt @ 4.78% Cu;
Inferred Resource - 2.1894 Mt @ 1.52% Cu.
Surubim open pit mine
Oxides
Measured+Indicated Resource - 5900 t @ 0.35% Cu;
Inferred Resource - 800 t @ 0.34% Cu.
Sulphides
Measured+Indicated Resource - 0.4112 Mt @ 0.88% Cu;
Inferred Resource - 0.0786 Mt @ 1.02% Cu.
R22W mine
Measured+Indicated Resource - 0.3083 Mt @ 0.54% Cu;
Inferred Resource - Nil.
NI 43-101 compliant Proved+Probable Ore Reserves as at 31 March 2017 (Ero Copper Corp. Technical Report, 2017) were:
Pilar underground mine - 6.191 Mt @ 1.91% Cu;
Vermelhos underground mine - 2.418 Mt @ 4.15% Cu;
Surubim open pit mine - 0.259 Mt @ 0.79% Cu;
TOTAL - 8.868 Mt @ 2.49% Cu.
This record has been updated from Mendonça, R., Reinhardt, M.C., Rodrigues, P.C., Viana, B.H.C. and Xavier, F.V., 2017 - 2017 Updated Mineral Resources and Mineral Reserves Statements of Mineração Caraíba's Vale do Curaçá Mineral Assets, Curaçá
Valley; prepared by SRK Consultores do Brasil Ltda; for Ero Copper Corp., 289p.
The most recent source geological information used to prepare this decription was dated: 2017.
Record last updated: 20/1/2022
This description is a summary from published sources, the chief of which are listed below.
© Copyright Porter GeoConsultancy Pty Ltd. Unauthorised copying, reproduction, storage or dissemination prohibited.
Caraiba
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Del-Rey Silva L J H R, Oliveira J G 1999 - Geology of the Caraiba copper mine and its surroundings in the Paleoproterozoic Curaca Belt - Curaca River valley, Bahia, Brazil: in Silva M G, Misi A (Ed.), 1999 Base Metal Deposits of Brazil CPRM, Brazil pp 25-32
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Huhn S.R.B., Silva, A.M., Ferreira, F.J.F. and Braitenberg, C., 2020 - Mapping New IOCG Mineral Systems in Brazil: The Vale do Curaca and Riacho do Pontal Copper Districts: in Minerals (MDPI) v.10, 29p. doi:10.3390/min10121074.
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Maier W D, Barnes S-J 1999 - The origin of Cu Sulfide deposits in the Curaca Valley, Bahia, Brazil: evidence from Cu, Ni, Se and Platinum-group element concentrations: in Econ. Geol. v94 pp 165-183
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Oliveira, E.P. and Tarney, J., 1995 - Genesis of the Precambrian copper-rich Caraiba hypersthenite-norite complex, Brazil: in Mineralium Deposita v.30, pp. 351-373
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Teixeir, J.B.G., Silva, M.G., Misi, A., Cruz, S.C.P. and Sa, J.H.S., 2010 - Geotectonic setting and metallogeny of the northern Sao Francisco craton, Bahia, Brazil: in J. of South American Earth Sciences v.30, pp. 71-83.
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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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