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Serra Pelada, Serra Leste |
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Para, Brazil |
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Au PGE PGM
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Super Porphyry Cu and Au
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The Serra Pelada Au-PGE deposit within the Serra Léste project area is located in the Carajás Mineral Province in the southeastern Amazon Craton, Brazil.
Since the discovery of the Serra Pelada Au-PGE deposit in the early 1980¹s by garimperos, (local miners and prospectors), it has been the object of one of the largest gold rushes in South American history, being worked by more than 100 000 garimperos at the peak of production activity
A current estimated resource, in the unmined portion of the deposit, is 56 t Au, 15 t Pd and 7 t Pt, grading 15.20 g/t Au, 4.09 g/t Pd and 1.89 g/t Pt (CVRD, 1998). Original pre-mining resources have been estimated at ~110 t Au, ~35t Pd and ~18 t Pt, although the uncertainty of these figures is high.
The deposit is located adjacent to a complex strike-slip system within the Itacaiúnas Belt of the northern Carajás Mineral Province of the southeastern Amazon Craton.
The principal suite within the Itacaiúnas Belt comprises the Late Archaean (ca 2.75 Ga), Itacaiúnas Supergroup consisting of a sequence of volcano-sedimentary rocks, dominated by mafic volcanics which have been metamorphosed to greenschist and amphibolite facies. Unconformably overlying the volcano-sedimentary sequence are rocks of the Aguas Claras and Rio Fresco Formations, extensive platform sequences of Archaean (ca 2.68 Ga) sandstones, conglomerates and siltstones, metamorphosed to lower greenschist and sub-greenschist facies. The supracrustal rocks of the Itacaiúnas Supergroup have been intruded by several Archaean to Proterozoic granitoids.
The Serra Pelada Au-PGE mineralisation is found entirely within the metasedimentary rocks of the Rio Fresco Formation that include, in sequence from oldest to youngest of, impure marble, carbonaceous and calcareous meta-siltstone, and red meta-siltstone. The majority (>75%) of the ore is hosted in the black, carbon-rich, lower part of the carbonaceous and calcareous meta-siltstone.
The epigenetic gold and PGE ores, which have undergone deep tropical weathering, exhibit a strong structural control, and are hosted in sub-greenschist facies carbonaceous and calcareous meta-siltstone, within the hinge zone of a reclined, tight, regional-scale F2 synform.
The geometry and localisation of high-grade ore shoots within the Serra Pelada deposit are controlled by three structural factors. These are: (1) the plunge of a major F2 fold hinge within the black carbonaceous and calcareous meta-siltstone, which is the main host for Au-PGE mineralisation; (2) the proximity of the F2 fold hinge to NNW-trending faults that were the ore-fluid channel; and (3) the lithological contacts between the carbonaceous and calcareous meta-siltstone and impure marble units.
Gold-PGE mineralisation is associated with the formation of magnetite- and hematite-rich hydrothermal breccias, massive zones of hematite metasomatism, intense sericite (white mica)-kaolin metasomatism, siderite veining and a jasperoid envelope of amorphous silica alteration hosting rare disseminated pyrite.
Virtually all of the Au-PGE ore-related mineral assemblages have undergone intense weathering to hydrated Fe-oxides and secondary clay minerals. The geochemistry of the primary Au-PGE ores at Serra Pelada displays many similarities to that of Fe-oxide Cu-Au deposits within the Carajįs Mineral Province, in terms of metal association (eg. Co, Ni, Cu, U), LREE enrichment and accompanying Fe-metasomatism.
The above is extracted from Grainger, et. al. 2002, a paper in the monograph: "Hydrothermal Iron Oxide Copper-Gold & Related Deposits: A Global Perspective" volume 2, published by PGC Publishing, Adelaide, Australia.
The full abstract summarising the deposit and the reference list from the paper can be displayed by selecting options offered below.
Abstract Reference list
For detail consult this paper or other reference(s) listed below.
The most recent source geological information used to prepare this decription was dated: 2001.
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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Selected References:
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Berni, G.V., Heinrich, C.A., Lobato, L.M. and Wall, V., 2016 - Ore mineralogy of the Serra Pelada Au-Pd-Pt deposit, Carajas, Brazil and implications for ore-forming processes: in Mineralium Deposita v.51, pp. 781-795
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Cabral A R, Lehmann B, Kwitko R, Costa C H C 2002 - The Serra Pelada Au-Pd-Pt deposit, Carajas Mineral Province, northern Brazil: reconnaissance mineralogy and chemistry of very high grade Palladian Gold mineralization: in Econ. Geol. v97 pp 1127-1138
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Cabral AR, Burgess R and Lehmann B, 2011 - Late Cretaceous bonanza-style metal enrichment in the Serra Pelada Au-Pd-Pt deposit, Para, Brazil: in Econ. Geol. v106 pp. 119-125
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Grainger C J, Groves D I, Costa C H C 2002 - The epigenetic sediment-hosted Serra Pelada Au-PGE deposit and its potential genetic association with Fe-oxide Cu-Au mineralization, Amazon Craton, Brazil: in Porter T M (Ed), 2002 Hydrothermal Iron Oxide Copper-Gold & Related Deposits: A Global Perspective PGC Publishing, Adelaide v2 pp 227-245
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Moroni M, Girardi V A, Ferrario A 2001 - The Serra Pelada Au-PGE deposit, Serra dos Carajas (Para State, Brazil): geological and geochemical indications for a composite mineralising process: in Mineralium Deposita v36 pp 768-785
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| References in PGC Publishing Books: | |
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Grainger C, Groves D I, 2002 - The Epigenetic Sediment-Hosted Serra Pelada Au-PGE Deposit and its Potential Genetic Association with Fe-oxide Cu-Au Mineralisation within the Carajas Mineral Province, Amazon Craton, Brazil, in Porter T M, (Ed.), Hydrothermal Iron Oxide Copper-Gold & Related Deposits: A Global Perspective, v2 pp 227-245
 Abstract
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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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