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Hydrothermal Alteration, Fluid Evolution, and Re-Os Geochronology of the Grota Funda Iron Oxide Copper-Gold Deposit, Carajás Province (Pará State), Brazil

2018; Volume: 113; Issue: 8 Linguagem: Inglês

10.5382/econgeo.2018.4612

1554-0774

Raphael Bianchi Hunger, Roberto Perez Xavier, Carolina Penteado Natividade Moreto, Jianfeng Gao,

earthquake and tectonic studies

Research Article| December 01, 2018 Hydrothermal Alteration, Fluid Evolution, and Re-Os Geochronology of the Grota Funda Iron Oxide Copper-Gold Deposit, Carajás Province (Pará State), Brazil R.B. Hunger; R.B. Hunger 1Institute of Geosciences, University of Campinas, 250 Carlos Gomes, Campinas, São Paulo 13083–855, Brazil †Corresponding author: e-mail, raphael.hunger@gmail.com Search for other works by this author on: GSW Google Scholar R.P. Xavier; R.P. Xavier 1Institute of Geosciences, University of Campinas, 250 Carlos Gomes, Campinas, São Paulo 13083–855, Brazil Search for other works by this author on: GSW Google Scholar C.P.N. Moreto; C.P.N. Moreto 1Institute of Geosciences, University of Campinas, 250 Carlos Gomes, Campinas, São Paulo 13083–855, Brazil Search for other works by this author on: GSW Google Scholar Jian-Feng Gao Jian-Feng Gao 2State Key Laboratory of Ore Deposit Geochemistry, Institute of Geochemistry, Chinese Academy of Sciences, 99 Lincheng West Road, Guiyang 550081, China Search for other works by this author on: GSW Google Scholar Economic Geology (2018) 113 (8): 1769–1794. https://doi.org/10.5382/econgeo.2018.4612 Article history accepted: 15 Nov 2018 first online: 04 Feb 2019 Cite View This Citation Add to Citation Manager Share Icon Share Facebook Twitter LinkedIn MailTo Tools Icon Tools Get Permissions Search Site Citation R.B. Hunger, R.P. Xavier, C.P.N. Moreto, Jian-Feng Gao; Hydrothermal Alteration, Fluid Evolution, and Re-Os Geochronology of the Grota Funda Iron Oxide Copper-Gold Deposit, Carajás Province (Pará State), Brazil. Economic Geology 2018;; 113 (8): 1769–1794. doi: https://doi.org/10.5382/econgeo.2018.4612 Download citation file: Ris (Zotero) Refmanager EasyBib Bookends Mendeley Papers EndNote RefWorks BibTex toolbar search Search Dropdown Menu toolbar search search input Search input auto suggest filter your search All ContentBy SocietyEconomic Geology Search Advanced Search Abstract The Grota Funda iron oxide copper-gold (IOCG) deposit is situated within a regional WNW-ESE–striking shear zone in the northwestern portion of the Carajás domain, an Archean (3.0–2.55 Ga) segment of the Carajás Province, Brazil. Metavolcano-sedimentary sequences of the Igarapé-Pojuca Group, comprising basalt, diabase, gabbro, dacite, and banded iron formations, are the main lithotypes recognized in the deposit area. In this sequence, mafic igneous rocks represent the main hosts to the copper (-gold) mineralization stages. The paragenetic evolution of the Grota Funda hydrothermal system encompasses an early high-temperature cal-cic-sodic alteration (albite-hastingsite-scapolite), followed by intense Fe metasomatism (magnetite-grunerite-almandine), potassic alteration with biotite, chlorite-quartz-tourmaline assemblage, and late carbonate-quartz veining. Copper (-gold) mineralization stages are spatially and temporally associated with iron-enriched (mineralization I), potassically altered (mineralization II), and chlorite-altered zones (mineralization III). Molybdenite from grunerite-magnetite veins yielded a Re-Os model age of 2530 ± 60 Ma, which is interpreted as the mineralization I age. The main sulfide ore (mineralization II) predominantly forms breccia bodies characterized by a chalcopyrite-magnetite-sphalerite-pyrrhotite assemblage. Chalcopyrite δ34S values (0.9 ± 0.9‰) point to a magmatic source for sulfur, probably leached from the host mafic rocks. Development of early and high-temperature (>500°C) alteration assemblages is attributed to regional circulation of deep-seated hypersaline and metalliferous fluids. Mixing with moderate- to high-salinity (24–29 wt % NaCl + CaCl2 equiv) and cooler fluids may have triggered ore precipitation in the main ore zone of mineralization II, due to a decrease in temperature and Cl– activity. Postore alteration assemblages resulted from considerable temperature and pH decreases. You do not have access to this content, please speak to your institutional administrator if you feel you should have access.