Tracing Fluid Sources for the Salobo and Igarapé Bahia Deposits: Implications for the Genesis of the Iron Oxide Copper-Gold Deposits in the Carajás Province, Brazil

Research Article| June 01, 2019 Tracing Fluid Sources for the Salobo and Igarapé Bahia Deposits: Implications for the Genesis of the Iron Oxide Copper-Gold Deposits in the Carajás Province, Brazil Gustavo H.C. de Melo; Gustavo H.C. de Melo 1 Department of Geology, Federal University of Ouro Preto (UFOP), Morro do Cruzeiro-Campus Morro Do Cruzeiro, s/n - Bauxita, 35400-000 Ouro Preto, Minas Gerais, Brazil † Corresponding author: e-mail, gustavo.melo@ufop.edu.br Search for other works by this author on: GSW Google Scholar Lena V.S. Monteiro; Lena V.S. Monteiro 1 Department of Geology, Federal University of Ouro Preto (UFOP), Morro do Cruzeiro-Campus Morro Do Cruzeiro, s/n - Bauxita, 35400-000 Ouro Preto, Minas Gerais, Brazil Search for other works by this author on: GSW Google Scholar Roberto P. Xavier; Roberto P. Xavier 3 Institute of Geosciences, University of Campinas (UNICAMP), R. João Pandiá Calógeras, 51, 13083-870 Campinas, São Paulo, Brazil Search for other works by this author on: GSW Google Scholar Carolina P.N. Moreto; Carolina P.N. Moreto 3 Institute of Geosciences, University of Campinas (UNICAMP), R. João Pandiá Calógeras, 51, 13083-870 Campinas, São Paulo, Brazil Search for other works by this author on: GSW Google Scholar Erika Santiago Erika Santiago 2 Institute of Geosciences, University of São Paulo (USP), Rua do Lago, 562, 05508-080 São Paulo, São Paulo, Brazil Search for other works by this author on: GSW Google Scholar Author and Article Information Gustavo H.C. de Melo 1 Department of Geology, Federal University of Ouro Preto (UFOP), Morro do Cruzeiro-Campus Morro Do Cruzeiro, s/n - Bauxita, 35400-000 Ouro Preto, Minas Gerais, Brazil Lena V.S. Monteiro 1 Department of Geology, Federal University of Ouro Preto (UFOP), Morro do Cruzeiro-Campus Morro Do Cruzeiro, s/n - Bauxita, 35400-000 Ouro Preto, Minas Gerais, Brazil Roberto P. Xavier 3 Institute of Geosciences, University of Campinas (UNICAMP), R. João Pandiá Calógeras, 51, 13083-870 Campinas, São Paulo, Brazil Carolina P.N. Moreto 3 Institute of Geosciences, University of Campinas (UNICAMP), R. João Pandiá Calógeras, 51, 13083-870 Campinas, São Paulo, Brazil Erika Santiago 2 Institute of Geosciences, University of São Paulo (USP), Rua do Lago, 562, 05508-080 São Paulo, São Paulo, Brazil † Corresponding author: e-mail, gustavo.melo@ufop.edu.br Publisher: Society of Economic Geologists Accepted: 30 Jan 2019 First Online: 24 Jun 2019 Online Issn: 1554-0774 Print Issn: 0361-0128 © 2019 Economic GeologyEconomic Geology Economic Geology (2019) 114 (4): 697–718. https://doi.org/10.5382/econgeo.4659 Article history Accepted: 30 Jan 2019 First Online: 24 Jun 2019 Cite View This Citation Add to Citation Manager Share Icon Share Facebook Twitter LinkedIn MailTo Tools Icon Tools Get Permissions Search Site Citation Gustavo H.C. de Melo, Lena V.S. Monteiro, Roberto P. Xavier, Carolina P.N. Moreto, Erika Santiago; Tracing Fluid Sources for the Salobo and Igarapé Bahia Deposits: Implications for the Genesis of the Iron Oxide Copper-Gold Deposits in the Carajás Province, Brazil. Economic Geology 2019;; 114 (4): 697–718. doi: https://doi.org/10.5382/econgeo.4659 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 Salobo and Igarapé Bahia iron oxide copper-gold (IOCG) deposits stand out as economically important deposits in the Carajás Province. Whereas granitoids and gneisses host the Neoarchean Salobo deposit, the Igarapé Bahia deposit occurs in volcanic rocks and associated sedimentary sequences. Paragenetic evolution of the IOCG alteration-mineralization evidences higher temperature conditions at Salobo (almandine-grunerite-biotite-magnetite) than at Igarapé Bahia (tourmaline-carbonate-magnetite-chlorite). At Salobo, iron enrichment at 565° ± 50°C was accompanied by hydrothermal fluids with magmatic or metamorphic compositions, as evidenced by grunerite (δ18OH2O = 7.20–8.50‰, δDH2O = −25.33 to −16.01‰), garnet (δ18OH2O = 7.10–9.70‰), and tourmaline (δ18OH2O = 5.07–7.37‰, δDH2O = −32.13 to +11.60‰). Fluids associated with potassic alteration at 565° ± 50°C also have a typical magmatic/metamorphic composition, indicated by biotite (δ18OH2O = 7.23–8.03‰, δDH2O = −40.94 to −25.94‰) and quartz (δ18OH2O = 7.52‰). Sulfur isotope signatures for chalcopyrite (0.81–1.28‰) and bornite (−0.37 to + 1.63‰) suggest a magmatic sulfur source at Salobo. For the Igarapé Bahia deposit, fluids associated with tourmaline display magmatic or metamorphic signatures (δ18OH2O = 5.07–7.37‰, δDH2O = −34.02 to −19.74‰, at 330° ± 50°C), but those associated with calcite (δ18OH2O = 1.68–3.10‰, 330° ± 50°C) and chlorite (δ18OH2O = 1.92–3.20‰, δDH2O = −57.36 to –21.34‰, 255° ± 50°C) evidence the input of 18O-depleted fluids. δ13CCO2 values (−9.32 to −4.93‰) for fluids in equilibrium with calcite also imply magmatic sources. Our data indicate that the main source of the ore-forming fluids for Salobo was derived from exsolved magmatic brines associated with crystallization of the coeval ca. 2.5 Ga granites. In contrast, though the early fluids at Igarapé Bahia were also magmatic-hydrothermal, the influx of 18O-depleted formation water was prominent during the later stages of ore genesis. You do not have access to this content, please speak to your institutional administrator if you feel you should have access.