Research Article| September 01, 2008 Tourmaline B-isotopes fingerprint marine evaporites as the source of high-salinity ore fluids in iron oxide copper-gold deposits, Carajás Mineral Province (Brazil) Roberto Perez Xavier; Roberto Perez Xavier * 11Departamento de Geologia e Recursos Naturais, Instituto de Geociências, Universidade Estadual de Campinas, 13083-970 Campinas (SP), Brazil *E-mail: xavier@ige.unicamp.br. Search for other works by this author on: GSW Google Scholar Michael Wiedenbeck; Michael Wiedenbeck 22GeoForschungsZentrum Potsdam, Telegrafenberg, 14473 Potsdam, Germany Search for other works by this author on: GSW Google Scholar Robert B. Trumbull; Robert B. Trumbull 22GeoForschungsZentrum Potsdam, Telegrafenberg, 14473 Potsdam, Germany Search for other works by this author on: GSW Google Scholar Ana M. Dreher; Ana M. Dreher 33Companhia de Pesquisa de Recursos Minerais/Serviço Geológico do Brasil, Av. Pasteur 404, 22290-240 Rio de Janeiro (RJ), Brazil Search for other works by this author on: GSW Google Scholar Lena V.S. Monteiro; Lena V.S. Monteiro 11Departamento de Geologia e Recursos Naturais, Instituto de Geociências, Universidade Estadual de Campinas, 13083-970 Campinas (SP), Brazil Search for other works by this author on: GSW Google Scholar Dieter Rhede; Dieter Rhede 22GeoForschungsZentrum Potsdam, Telegrafenberg, 14473 Potsdam, Germany Search for other works by this author on: GSW Google Scholar Carlos E.G. de Araújo; Carlos E.G. de Araújo 11Departamento de Geologia e Recursos Naturais, Instituto de Geociências, Universidade Estadual de Campinas, 13083-970 Campinas (SP), Brazil Search for other works by this author on: GSW Google Scholar Ignacio Torresi Ignacio Torresi 11Departamento de Geologia e Recursos Naturais, Instituto de Geociências, Universidade Estadual de Campinas, 13083-970 Campinas (SP), Brazil Search for other works by this author on: GSW Google Scholar Geology (2008) 36 (9): 743–746. https://doi.org/10.1130/G24841A.1 Article history received: 02 Mar 2008 rev-recd: 16 May 2008 accepted: 10 Jun 2008 first online: 02 Mar 2017 Cite View This Citation Add to Citation Manager Share Icon Share MailTo Twitter LinkedIn Tools Icon Tools Get Permissions Search Site Citation Roberto Perez Xavier, Michael Wiedenbeck, Robert B. Trumbull, Ana M. Dreher, Lena V.S. Monteiro, Dieter Rhede, Carlos E.G. de Araújo, Ignacio Torresi; Tourmaline B-isotopes fingerprint marine evaporites as the source of high-salinity ore fluids in iron oxide copper-gold deposits, Carajás Mineral Province (Brazil). Geology 2008;; 36 (9): 743–746. doi: https://doi.org/10.1130/G24841A.1 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 SocietyGeology Search Advanced Search Abstract The Carajás Mineral Province in northern Brazil contains a variety of world-class (>100 Mt ore) iron oxide copper-gold (IOCG) deposits, including the only Archean examples of this deposit class (e.g., the Igarapé Bahia/Alemão and Salobo deposits). Tourmaline of schorl-dravite composition, a common gangue mineral in these deposits, precipitated shortly prior to and after the ore assemblage. A boron isotope study of texturally different tourmaline from three IOCG deposits (Igarapé Bahia, Salobo, and Sossego) using secondary ion mass spectrometry (SIMS) provides new evidence in the long-standing debate of magmatic versus non-magmatic sources for the high salinity (up to 50 wt% NaCl equiv.) of ore fluids in these deposits. Values of δ11B from 14‰ to 26.5‰ for the Igarapé Bahia and Salobo deposits confirm marine evaporite–derived brines in the ore fluids, whereas lower δ11B values for the Igarapé Bahia deposit (5.8‰ to 8.8‰) suggest that these fluids may have mixed with an isotopically different hydrothermal fluid, or one that had a mixed boron source. More variable and isotopically lighter boron in tourmaline from the Sossego deposit (−8‰ to 11‰) is attributed to mixed sources, including light boron leached from felsic intrusive and volcanic host rocks, and heavy boron derived from marine evaporites. The boron isotope data indicate that the characteristic high salinity of the ore fluids in the Carajás Mineral Province was acquired by the interaction of hydrothermal fluids with marine evaporites. For IOCG deposits that contain tourmaline as a common gangue mineral, boron isotopes offer a valuable tool to constrain the high-salinity source problem, which is a critical issue in metallogenesis of IOCG deposits worldwide. You do not have access to this content, please speak to your institutional administrator if you feel you should have access.
The Bacuri copper deposit is located about 9 km east of the world-class Sossego iron oxide-copper-gold deposit in the Carajás Province.It is hosted by the ca.2.84 Ga Serra Dourada granite, the Bacuri Porphyry, and subordinated gabbro.The Bacuri deposit is situated within the regional-scale, WNW-ESE-trending ductile Canaã shear zone, characterized by early albite, scapolite-magnetite, potassium feldspar and biotite-scapolite-magnetite hydrothermal alteration zones.Copper mineralization was controlled and largely simultaneous to the development of a NE-SW-trending transcurrent fault zone.Within this zone, intense chlorite alteration, silicification and quartz veining overlap previous hydrothermal stages.Copper ore (chalcopyrite-pyrite-magnetite) is disseminated and related to veins and breccias.Chalcopyrite occurs along the mylonitic foliation in chlorite alteration zones, in brecciated quartz-(muscovite-fluorite) and undeformed milky quartz veins and in late potassium feldspar-epidote veinlets with open space textures.The relative temporal history of the Bacuri deposit reveals significant changes in physico-chemical parameters during the system evolution.Contribution of hot hypersaline metalliferous fluids was important during early sodic and potassic alteration stages and related to a regional hydrothermal system developed at relatively deep crustal levels.Influx of externally derived diluted fluids within the NE-SW-trending fault zone favoured the late shallow-emplaced chlorite alteration and silicification, and may have triggered the ore deposition due to decrease of temperature and salinity, accompanied by ƒO 2 increase and pH decrease.Such significant changes could indicate a hybrid system that evolved in multiple pulses during progressive exhumation.
Research Article| May 01, 2015 Neoarchean and Paleoproterozoic Iron Oxide-Copper-Gold Events at the Sossego Deposit, Carajás Province, Brazil: Re-Os and U-Pb Geochronological Evidence* C. P. N. Moreto; C. P. N. Moreto 1Institute of Geosciences, University of Campinas, Campinas, São Paulo, 13083-870, Brazil Search for other works by this author on: GSW Google Scholar L. V. S. Monteiro; L. V. S. Monteiro † 2Institute of Geosciences, University of São Paulo, São Paulo 05508-080, Brazil †Corresponding author: e-mail, lena.monteiro@usp.br Search for other works by this author on: GSW Google Scholar R. P. Xavier; R. P. Xavier 1Institute of Geosciences, University of Campinas, Campinas, São Paulo, 13083-870, Brazil Search for other works by this author on: GSW Google Scholar R. A. Creaser; R. A. Creaser 3Department of Earth and Atmospheric Sciences, University of Alberta, Edmonton, Alberta T6G 2E3, Canada Search for other works by this author on: GSW Google Scholar S. A. DuFrane; S. A. DuFrane 3Department of Earth and Atmospheric Sciences, University of Alberta, Edmonton, Alberta T6G 2E3, Canada Search for other works by this author on: GSW Google Scholar C. C. G. Tassinari; C. C. G. Tassinari 2Institute of Geosciences, University of São Paulo, São Paulo 05508-080, Brazil Search for other works by this author on: GSW Google Scholar K. Sato; K. Sato 2Institute of Geosciences, University of São Paulo, São Paulo 05508-080, Brazil Search for other works by this author on: GSW Google Scholar A. I. S. Kemp; A. I. S. Kemp 4Centre for Exploration Target, University of Western Australia, Perth 6009, Australia Search for other works by this author on: GSW Google Scholar W. S. Amaral W. S. Amaral 1Institute of Geosciences, University of Campinas, Campinas, São Paulo, 13083-870, Brazil Search for other works by this author on: GSW Google Scholar Economic Geology (2015) 110 (3): 809–835. https://doi.org/10.2113/econgeo.110.3.809 Article history received: 21 Sep 2013 accepted: 06 Aug 2014 first online: 09 Mar 2017 Cite View This Citation Add to Citation Manager Share Icon Share Facebook Twitter LinkedIn MailTo Tools Icon Tools Get Permissions Search Site Citation C. P. N. Moreto, L. V. S. Monteiro, R. P. Xavier, R. A. Creaser, S. A. DuFrane, C. C. G. Tassinari, K. Sato, A. I. S. Kemp, W. S. Amaral; Neoarchean and Paleoproterozoic Iron Oxide-Copper-Gold Events at the Sossego Deposit, Carajás Province, Brazil: Re-Os and U-Pb Geochronological Evidence. Economic Geology 2015;; 110 (3): 809–835. doi: https://doi.org/10.2113/econgeo.110.3.809 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 Sossego iron oxide-copper-gold (IOCG) deposit is situated within the WNW-ESE-trending Canaã shear zone in the southern Copper belt, Carajás province, Brazil. The Sossego deposit consists of two major groups of orebodies (Sequeirinho-Pista-Baiano and Sossego-Curral). The Sequeirinho-Pista-Baiano orebodies are characterized by deep-emplaced magnetite-(apatite) and albite-actinolite-rich zones, whereas the Sossego-Curral orebodies have predominant potassic and chlorite alteration typical of shallow crustal levels. U-Pb (SHRIMP IIe and LA-ICPMS) geochronology on host rocks reveals Mesoarchean (3.08 Ga Xingu Complex, ca. 2.99 Ga Sequeirinho Granite and 2.97 Ga Pista felsic metavolcanic rock) and bimodal Neoarchean (ca. 2.74 Ga Sossego granophyric granite, Curral Granite and gabbronorite) units. Dating of hydrothermal monazite (U-Pb LA-MC-ICPMS) and molybdenite (Re-Os NTIMS) of the Sequeirinho-Pista orebodies rendered ages of ca. 2.71 to 2.68 Ga, while ore-related monazite of the Sossego-Curral orebodies yielded ages of ca. 1.90 to 1.88 Ga. The Neoarchean IOCG-forming events reflect coupling of ductile sinistral transpression with NNE–directed oblique shortening and Neoarchean magmatism (ca. 2.7 Ga). The shallow-emplaced Paleoproterozoic system, formed after progressive exhumation of the deep-emplaced Neoarchean IOCG deposits, coincides in age with the emplacement of 1.88 Ga A-type granites: the latter may have caused regional circulation of magmatic and externally derived fluids along crustal discontinuities, favoring copper-gold ore deposition as well as metallogenic diversity in the Carajás province (e.g., Sn, W, Au-Pd-Pt deposits). You do not have access to this content, please speak to your institutional administrator if you feel you should have access.