Mineral chemistry of ore and hydrothermal alteration at the Sossego iron oxide-copper-gold deposit, Carajas Mineral Province, Brazil

Author(s)

Soares Monteiro, Lena Virginia ^[1] ; Xavier, Roberto Perez ^[1] ; Hitzman, Murray W. ^[2] ; Juliani, Caetano ^[3] ; de Souza Filho, Carlos Roberto ^[1] ; Carvalho, Emerson de R. ^[1]

Affiliation

^[1] Univ Estadual Campinas, Inst Geociencias, BR-13083970 Campinas, SP - Brazil

^[2] Colorado Sch Mines, Dept Geol & Geol Engn, Golden, CO 80401 - USA

^[3] Univ Sao Paulo, Inst Geociencias, BR-05508080 Sao Paulo - Brazil

• Document type: Review article
• Source: ORE GEOLOGY REVIEWS; v. 34, n. 3, p. 317-336, NOV 2008.
• Web of Science Citations: 41

Abstract

The Sossego iron oxide-copper-gold deposit in the Carajas Mineral Province comprises two major orebodies, Sequeirinho and Sossego. Sodic alteration (albite-hematite) and sodic-calcic alteration zones represented by albite, ferro-edenite/hastingsite (up to 3.8 wt.% CI), actinolite/magnesiohornblende, magnetite, titanite, epidote, and calcite are predominant at Sequeirinho. Magnetite bodies with envelopes of apatite-rich actinolitite were formed with the sodic-calcic event at high temperatures (similar to 500 degrees C at 1.4 kbar). In the Sossego orebody. potassic alteration with orthoclase and Cl-fich biotite (up to 3.1 wt.%) and chloritization are the main alteration types. Mineralized breccias in both orebodies have coarse-grained zoned actinolite/ferro-actinolite, Cl-apatite, and magnetite within the matrix. Sulfides occur in equilibrium with a paragenetically late calcite-quartz-chlorite-epidote-allanite assemblage. The Al-IV contents of the chlorite indicate crystallization at temperatures below 300 degrees C. Chalcopyrite occurs associated with pyrite (up to 2.3 wt.% Co and 0.2 wt% Ni), native gold (up to 14.9 wt.% Ag), siegenite, millerite, vaesite, Pd-melonite, and hessite. Dilution and cooling of the hot metalliferous fluid (>500 degrees C) by mixing with meteoric fluids may have been the main mechanisms responsible for the deposition of metals transported as metal chloride complexes in both orebodies of the Sossego deposit. (C) 2008 Elsevier B.V. All rights reserved. (AU)

• FAPESP's process: 03/09916-6 - Tectonic environment and metallogenesis of the gold and copper deposits of the Tapajós and Carajás mineral provinces
• Grantee: Carlos Roberto de Souza Filho
• Support Opportunities: PRONEX Research - Thematic Grants