ABSTRACT

   The Serra Pelada Au-PGE deposit is located within the Carajás Mineral Province of the southeastern Amazon Craton, Brazil. Gold-PGE ores are epigenetic and display a strong structural control, being hosted in sub-greenschist facies carbonaceous and calcareous metasiltstone, within the hinge zone of a reclined, tight, regional-scale F2 synform. Although the entire orebody has undergone deep tropical weathering, some evidence of the original hydrothermal alteration is preserved. Gold-PGE mineralization 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. All other Au-PGE ore-related mineral assemblages have undergone intense weathering to hydrated Fe-oxides and secondary clay minerals, preventing further description of primary ore and alteration features. The geochemistry of the primary Au-PGE ores at Serra Pelada displays many similarities to that of Fe-oxide Cu-Au deposits within the Carajás Mineral Province, and indeed world-wide, in terms of metal association (e.g. Co, Ni, Cu, U), LREE enrichment and associated Fe-metasomatism. The Au-Pd-Pt association also suggests ore metal transport in acid, oxidizing, chloride-rich fluids, similar to those for Fe-oxide Cu-Au deposits. In combination with these similarities, and the location of the Serra Pelada Au-Pd-Pt deposit, it is suggested that the latter represents a distal equivalent to the Fe-oxide Cu-Au deposits and, as such, a target that may have been overlooked during exploration programs around such terrains globally.

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