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Multistage Evolution of the Neoarchean (ca. 2.7 Ga) Igarapé Cinzento (GT-46) Iron Oxide Copper-Gold Deposit, Cinzento Shear Zone, Carajás Province, Brazil

2019; Volume: 114; Issue: 1 Linguagem: Inglês

10.5382/econgeo.2019.4617

1554-0774

Poliana Iara de Freitas Toledo, Carolina Penteado Natividade Moreto, Roberto Perez Xavier, Jianfeng Gao, José Henrique da Silva Nogueira de Matos, Gustavo Henrique Coelho de Melo,

Geochemistry and Elemental Analysis

Research Article| February 01, 2019 Multistage Evolution of the Neoarchean (ca. 2.7 Ga) Igarapé Cinzento (GT-46) Iron Oxide Copper-Gold Deposit, Cinzento Shear Zone, Carajás Province, Brazil Poliana Iara de Freitas Toledo; Poliana Iara de Freitas Toledo 1Institute of Geosciences, University of Campinas, Campinas, São Paulo, 13083-855, Brazil †Corresponding author: e-mail, toledopoliana@gmail.com Search for other works by this author on: GSW Google Scholar Carolina Penteado Natividade Moreto; Carolina Penteado Natividade Moreto 1Institute of Geosciences, University of Campinas, Campinas, São Paulo, 13083-855, Brazil Search for other works by this author on: GSW Google Scholar Roberto Perez Xavier; Roberto Perez Xavier 1Institute of Geosciences, University of Campinas, Campinas, São Paulo, 13083-855, Brazil Search for other works by this author on: GSW Google Scholar Jianfeng Gao; Jianfeng Gao 2State Key Laboratory of Ore Deposit Geochemistry, Institute of Geochemistry, Chinese Academy of Sciences, Guiyang, 550002, China Search for other works by this author on: GSW Google Scholar José Henrique da Silva Nogueira de Matos; José Henrique da Silva Nogueira de Matos 1Institute of Geosciences, University of Campinas, Campinas, São Paulo, 13083-855, Brazil Search for other works by this author on: GSW Google Scholar Gustavo Henrique Coelho de Melo Gustavo Henrique Coelho de Melo 3Geology Department, Federal University of Ouro Preto, Ouro Preto, Minas Gerais, 35400-000, Brazil Search for other works by this author on: GSW Google Scholar Author and Article Information Poliana Iara de Freitas Toledo 1Institute of Geosciences, University of Campinas, Campinas, São Paulo, 13083-855, Brazil Carolina Penteado Natividade Moreto 1Institute of Geosciences, University of Campinas, Campinas, São Paulo, 13083-855, Brazil Roberto Perez Xavier 1Institute of Geosciences, University of Campinas, Campinas, São Paulo, 13083-855, Brazil Jianfeng Gao 2State Key Laboratory of Ore Deposit Geochemistry, Institute of Geochemistry, Chinese Academy of Sciences, Guiyang, 550002, China José Henrique da Silva Nogueira de Matos 1Institute of Geosciences, University of Campinas, Campinas, São Paulo, 13083-855, Brazil Gustavo Henrique Coelho de Melo 3Geology Department, Federal University of Ouro Preto, Ouro Preto, Minas Gerais, 35400-000, Brazil †Corresponding author: e-mail, toledopoliana@gmail.com Publisher: Society of Economic Geologists Accepted: 10 Dec 2018 First Online: 28 Feb 2019 Online Issn: 1554-0774 Print Issn: 0361-0128 © 2019 Economic GeologyEconomic Geology Economic Geology (2019) 114 (1): 1–34. https://doi.org/10.5382/econgeo.2019.4617 Article history Accepted: 10 Dec 2018 First Online: 28 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 Poliana Iara de Freitas Toledo, Carolina Penteado Natividade Moreto, Roberto Perez Xavier, Jianfeng Gao, José Henrique da Silva Nogueira de Matos, Gustavo Henrique Coelho de Melo; Multistage Evolution of the Neoarchean (ca. 2.7 Ga) Igarapé Cinzento (GT-46) Iron Oxide Copper-Gold Deposit, Cinzento Shear Zone, Carajás Province, Brazil. Economic Geology 2019;; 114 (1): 1–34. doi: https://doi.org/10.5382/econgeo.2019.4617 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 Igarapé Cinzento (GT-46) iron oxide copper-gold deposit is located in the northwestern part of the Cinzento shear zone in Carajás province, Brazil. Copper mineralization in the deposit is hosted by a hydrothermally altered metavolcanosedimentary sequence that consists of interlayered amphibolites, (actinolite)-biotite schists, almandine-biotite schists, and metamorphosed banded iron formations, intruded by granitoids (tonalite to granite) and mafic dikes.The complex evolution of the deposit involved (1) deposition of a volcanosedimentary sequence (2774 ± 19 Ma U-Pb zircon), (2) a tectonometamorphic event (Dn = upper amphibolite facies), restricted in time between 2.77 and 2.72 Ga, (3) development of the Cinzento shear zone (Dn + 1) at 2.72 Ga, with associated hydrothermal activity and deposit formation, (4) superimposed hydrothermal events (ca. 2.6 and 2.5 Ga), and (5) granitoid emplacement at ca 2.5 Ga in the region.The GT-46 deposit is the result of overprinting hydrothermal stages with at least two distinct mineralization events. Variations in alteration styles are a consequence of changes in the mechanisms of fluid control, first regulated by ductile deformation and later by brittle fracturing. Early hydrothermal alteration is characterized by zones of sodic-calcic and potassic alteration as well as iron metasomatism with associated disseminated mineralization I, controlled by ductile structures (chalcopyrite-bornite-magnetite, 2718 ± 56 Ma, Re-Os molybdenite). Veins and breccias with chalcopyrite-magnetite(-chlorite-calcite-quartz) represent an overprinting episode of mineralization (II) at ca. 2.6 Ga. Late alteration stages (ca. 2.5 Ga) represent fluid remobilization with chloritization zones and crystal growth spatially related to pegmatite intrusions. Re-Os molybdenite ages of 2503 ± 51 and 2449 ± 44 Ma provide evidence for younger episodes of hydrothermal fluid circulation in the deposit.Fluid inclusion study reveals aqueous-saturated, highly saline (32−>50 wt % NaCl equiv, total homogenization temperature [Tht] = 203°−>450°C) and carbonic fluids (CO2 melting temperature [Tmco2] = –56.3° to –54.5°C) for early alteration zones and saline (2.1–27.5 wt % NaCl equiv, Tht = 153.3°–215.5°C) solutions for late alteration zones. These data provide evidence for several alternative fluids involved in the evolution of the deposit: (1) hypersaline fluids derived from hydrothermal-magmatic brines or evaporative brines/evaporite-derived fluids, (2) saline solutions generated by progressive dilution of primary hypersaline fluids with shallower, colder, and less saline fluids (e.g., meteoric, seawater), and (3) carbonic components sourced from magmatic fluids, devolatilization of carbonate units and, partially, metamorphic fluids.Sulfur is interpreted to have been leached from country rocks in the earlier hydrothermal stages (mineralization I, δ34S = 0.01–1.99‰), and to have come from mixed granitic and external oxidized sources for later overprinting events (mineralization II, δ34S = 9.75–11.25‰). These data provide evidence for the recurrence of hydrothermal activity, indicating the existence of different potential sources of metals and sulfur during the evolution of the deposit. 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