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Santa Quiteria, Itataia |
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Ceara, Brazil |
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U P
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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 Santa Quitéria or Itataia phosphate - uranium deposit is located ~45 km SE of the town of Santa Quitéria and ~170 km SW of Fortaleza in the state of Ceará, Brazil.
The deposit lies within the Borborema Province of northeast Brazil, which represents the western part of a major Brasiliano/Pan-African orogenic belt that can be traced into Central Africa based on pre-drift reconstruction. The province separates the São Luis and São Francisco cratons and comprises a number of distinctive crustal domains, ranging from Archaean to Neoproterozoic in age, that were deformed during the convergence of the West African-São Luis, Amazonian, and São Francisco-Congo cratons at around 600 Ma. In the northern half of the province, north of the generally east-west trending Patos lineament, the basement architecture is dominated by major NE-SW trending structures and is composed of mid-Palaeoproterozoic gneisses that contain several smaller inliers of Archaean crustal fragments. These are overlain by a number of supracrustal sequences ranging from Palaeoproterozoic to Neoproterozoic in age. Neoproterozoic to Cambrian granitoids (622 to 532 Ma), related to the Brasiliano orogenesis, intrude both basement and supracrustal rocks. The northern Borborema Province can be correlated with the Dahomey Province, in the southern part of West Africa (Santos et al., 2003).
Three major crustal blocks make up this northern portion of the Borborema Province, each separated by a major NE-SW-trending linear structure. These are, from SE to NW, the:
(i) Rio Grande do Norte Terrane, which lies between the Patos lineament to the south and the Senador Pompeu Lineament to the NW, and comprises Archaean and Palaeoproterozoic basement, overlain by the ~1.8 Ga Orós volcano-sedimentary sequence and the Neoproterozoic supracrustal rocks of the Seridó Fold Belt;
(ii) Ceará Central terrane, which is situated between the NE-SW-trending Senador Pompeu and Transbrasiliano lineaments and is represented by a lower-Palaeoproterozoic gneissic basement with 2.13 Ga tonalite and granodiorite, that also incorporates the Archaean Tróia-Tauá Massif nucleus (3.04 to 2.77 Ga metabasalt, mafic-ultramafic sills, schist and quartzite), Neoproterozoic supracrustal rocks, and the Santa Quitéria-Tamboril Complex, a Neoproterozoic continental magmatic arc (with which the Itataia deposit is associated), interpreted to have resulted from the southeastward subduction of oceanic crust during convergence between the West African-São Luis craton and NW Ceará; and
(iii) Médio Coreaú Domain, which comprises early Palaeoproterozoic gneisses, migmatites and granulites, overlain by volcano-sedimentary sequences, with ages from late Palaeoproterozoic (Saquinho Sequence) to Neoproterozoic (Martinópole Group), intruded by Brasiliano/Panafrican granitoids
Santa Quitéria-Tamboril Complex consists of granitic gneiss domes derived from strongly migmatised and granitised sedimentary, volcanic and plutonic rocks, and is intruded into the metasediments of the lower-Palaeoproterozoic gneissic basement (quartz-feldspar gneiss and migmatite, sillimanite quartzite and muscovite quartzite, amphibolite, garnet gneiss and migmatite and calc-silicate marble), interpreted to represent protoliths of a sandstone, arkose, limestone sequence with some marls which have been intensely folded, possibly during the 2.0 Ga Transamazonian event, but definitely during the 650 to 470 Ma Brasiliano orogeny. Several generations of late- to post-tectonic granite were emplaced during the Brasiliano orogeny. Autochthonous, synorogenic, katazonal anatectic granites (650 Ma) occur within the older complexes, while late-orogenic (~550 Ma) intrusions are rare in the vicinity of Itataia, although leucocratic, peraluminous post-orogenic granites (510 to 450 Ma) were emplaced along dilational lineaments. Numerous post-orogenic granitic and pegmatitic apophyses and stocks that range from a few cm to tens of metres thick intrude the older rocks (Santos et al., 2003).
The main country rocks in the Itataia district comprise gneisses and carbonate rocks of the Siderian-Rhyacian Early Palaeoproterozoic Caicó Group that have undergone upper amphibolite to granulite facies metamorphism, responsible for the development of a granoblastic texture. The gneisses are well foliated biotite-garnet-sillimanite gneiss and amphibole gneiss. The rock forming assemblages include microcline, plagioclase, quartz, biotite and garnet porphyroblasts with accessory titanite, zircon and apatite. The carbonate unit includes light grey to brown pure and impure marbles (with a planar fabric of interlayered phlogopite, graphite and tremolite) and green calc-silicates (layers of a few cm to 10 m in thickness composed of quartz, diopside, tremolite, feldspars, biotite, scapolite and titanite) occurring as lenses as much as 10 km in length intercalated with the gneisses.
The host metamorphic sequence is variously regarded as Palaeoproterozoic (Santos et al., 2003; Dahlkamp, 2010), Neoproterozoic (Veríssimo, 2010), although all agree the mineralisation was associated with the late Neoproterozoic Brasiliano event. The mineralisation would appear to be related to a magmatic source rather than having been derived from the host metasediments (Dahlkamp, 2010; Veríssimo, 2010).
Collophane is the principal phosphate and uranium mineral, containing 60 to 150 ppm U per 1% of P2O5. No discrete uranium minerals have been identified. Collophane occurs as an almost monomineralic rock (~80% collophane), referred to as collophanite, which is stained brownish-red by iron oxide, and also contains calcite, graphite and ankerite when in marble, and albite, microcline, chlorite, zircon and calcite when in quartzo-feldspathic rocks. The collophanite is a light-rosy hydrothermal rock (matrix composed of apatite and clay material), dotted by dark, up to 1 mm-sized amphiboles and to a lesser extent whitish yellow cavities filled with carbonate, apatite and minor albite (Veríssimo, 2010; Castro et al., 2005).
Alteration products depends upon the host. When in granite the assemblage is characterised by quartz removal, albitisation of microcline and oligoclase, chloritisation, and hematite alteration of biotite. In gneiss the alteration comprises chloritisation of garnet and biotite, sericitisation of microcline and plagioclase, strong albitisation, analcime formation, and impregnation by collophane. Marbles are subjected to partial scapolitisation, superimposed late albitisation and fluor-apatite (Dahlkamp, 2010; Veríssimo, 2010).
The mineralisation at Itataia is hosted by calc-silicate rocks and by less extensive saccharoidal marbles. Subordinately, it is found in the paragneiss-migmatite domain or close to its contact with the carbonate rocks. The ore occurs as lenticular lodes (generally from 0.3 to 0.5 m thick, but locally up to tens of metres) of massive collophanite that fill cavities that are concordant with the main metamorphic foliation/banding of the host rocks, and as disseminated collophane in the carbonate and migmatitic paragneiss, and as lesser crosscutting veins and stockworks. Subordinately ore occurs in feldspathic rocks and carbonaceous breccia associated with marbles, containing Zr-rich material (Dahlkamp, 2010; Castro et al., 2005).
The main mineral body has a lateral extent of approximately 800 m in an east-west direction, by 250 to 400 m north-south and occurs from the surface to a depth of 180 m (Industrias Nucleares do Brasil website, 2012).
The Santa Quitéria/Itataia deposit has geological resources of (Industrias Nucleares do Brasil website, 2012):
142 500 t of phosphate-associated uranium,
The mining reserve comprises 79.5 Mt @ 11% P2O5 and 998 ppm of U3O8
containing 8.9 Mt of P2O5, 79.3 Kt of U3O8.
Also contained are ~300 million cubic metres of marble that can be used, totally uranium free.
The most recent source geological information used to prepare this decription was dated: 2012.
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.
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Verissimo, C.U.V., Santos, R.V., Parente, C.V., de Oliveira, C.G., Cavalcanti, J.A.D. and Neto, J.A.N., 2016 - The Itataia phosphate-uranium deposit (Ceara, Brazil) new petrographic, geochemistry and isotope studies: in J. of South American Earth Sciences v.70, pp. 115-144.
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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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