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Cyclic Dilution of Magmatic Metal-Rich Hypersaline Fluids by Magmatic Low-Salinity Fluid: A Major Process Generating the Giant Epithermal Polymetallic Deposit of Cerro de Pasco, Peru

2018; Volume: 113; Issue: 4 Linguagem: Inglês

10.5382/econgeo.2018.4573

1554-0774

Bertrand Rottier, Kalin Kouzmanov, V. Casanova, Marküs Wälle, Lluı́s Fontboté,

High-pressure geophysics and materials

Research Article| June 01, 2018 Cyclic Dilution of Magmatic Metal-Rich Hypersaline Fluids by Magmatic Low-Salinity Fluid: A Major Process Generating the Giant Epithermal Polymetallic Deposit of Cerro de Pasco, Peru B. Rottier; B. Rottier 1Department of Earth Sciences, University of Geneva, 1205 Geneva, Switzerland*Present address: Bayerisches Geoinstitut, University of Bayreuth, 95440 Bayreuth, Germany. †Corresponding author: e-mail, Bertrand.Rottier@gmail.com Search for other works by this author on: GSW Google Scholar K. Kouzmanov; K. Kouzmanov 1Department of Earth Sciences, University of Geneva, 1205 Geneva, Switzerland Search for other works by this author on: GSW Google Scholar V. Casanova; V. Casanova 1Department of Earth Sciences, University of Geneva, 1205 Geneva, Switzerland Search for other works by this author on: GSW Google Scholar M. Wälle; M. Wälle 2Institute of Geochemistry and Petrology, ETH Zürich, 8092 Zürich, Switzerland**Present address: Memorial University of Newfoundland, CREAIT, CRC, and CFI Services (CCCS), Bruneau Centre for Research and Innovation, St. John’s, Newfoundland and Labrador A1C 5S7, Canada. Search for other works by this author on: GSW Google Scholar L. Fontboté L. Fontboté 1Department of Earth Sciences, University of Geneva, 1205 Geneva, Switzerland Search for other works by this author on: GSW Google Scholar Author and Article Information B. Rottier 1Department of Earth Sciences, University of Geneva, 1205 Geneva, Switzerland*Present address: Bayerisches Geoinstitut, University of Bayreuth, 95440 Bayreuth, Germany. K. Kouzmanov 1Department of Earth Sciences, University of Geneva, 1205 Geneva, Switzerland V. Casanova 1Department of Earth Sciences, University of Geneva, 1205 Geneva, Switzerland M. Wälle 2Institute of Geochemistry and Petrology, ETH Zürich, 8092 Zürich, Switzerland**Present address: Memorial University of Newfoundland, CREAIT, CRC, and CFI Services (CCCS), Bruneau Centre for Research and Innovation, St. John’s, Newfoundland and Labrador A1C 5S7, Canada. L. Fontboté 1Department of Earth Sciences, University of Geneva, 1205 Geneva, Switzerland †Corresponding author: e-mail, Bertrand.Rottier@gmail.com Publisher: Society of Economic Geologists Accepted: 19 Mar 2018 First Online: 18 May 2018 Online Issn: 1554-0774 Print Issn: 0361-0128 © 2018 Economic GeologyEconomic Geology Economic Geology (2018) 113 (4): 825–856. https://doi.org/10.5382/econgeo.2018.4573 Article history Accepted: 19 Mar 2018 First Online: 18 May 2018 Cite View This Citation Add to Citation Manager Share Icon Share Facebook Twitter LinkedIn MailTo Tools Icon Tools Get Permissions Search Site Citation B. Rottier, K. Kouzmanov, V. Casanova, M. Wälle, L. Fontboté; Cyclic Dilution of Magmatic Metal-Rich Hypersaline Fluids by Magmatic Low-Salinity Fluid: A Major Process Generating the Giant Epithermal Polymetallic Deposit of Cerro de Pasco, Peru. Economic Geology 2018;; 113 (4): 825–856. doi: https://doi.org/10.5382/econgeo.2018.4573 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 giant mid-Miocene Cerro de Pasco Cordilleran polymetallic (Zn-Pb-Ag-Cu-Bi) deposit in central Peru formed during three successive mineralization stages resulting in low- to high-sulfidation mineral associations emplaced at a paleodepth from 1 wt % Mn, Fe, Zn, and Pb), and its high Li, B, As, and Sb contents (up to several thousands of ppm). The obtained results suggest that the moderate-salinity metal-rich magmatic fluid results from mixing at depth between metal-rich hypersaline fluids and low-salinity magmatic fluids exsolved late in the lifetime of the magmatic-hydrothermal system. The moderate-salinity metal-rich magmatic fluid resulting from this deep mixing rose to the epithermal environment, where it in turn mixed with low-salinity fluids that were stored below the paleowater table and had similar temperatures to the moderate-salinity fluid. In contrast, enargite-pyrite veins of stage C2 were formed by the ascent of CO2-bearing, contracted vapor-like fluids that subsequently mixed with cold meteoric water. No interaction with the moderate-salinity, metal-rich magmatic fluids has been registered in stage C2.The similarity between fluid compositions and evolution during stages A, B1, B2, and C1 contrasts with their significantly different mineral assemblages that are rather controlled by changing fo2, pH,fs2 and temperature. Trace element LA-ICP-MS analyses of sphalerite, pyrite, and enargite also reveal important compositional differences. The trace elements in the measured minerals reside to a significant extent in micro- to nanoscale solid sulfide and/or sulfosalt inclusions. A direct correlation between fluid composition recorded in the studied fluid inclusion assemblages and the measured trace element composition of sphalerite, pyrite, and enargite has not been found in most cases.The cyclic rise of metal-rich, moderately saline fluids that issued from dilution of hypersaline fluids stored at depth by low-salinity magmatic fluids is a major process in the formation of stages A, B1, B2, and C1 of the giant epithermal polymetallic deposit of Cerro de Pasco. Such a mechanism may also explain moderate-salinity fluids (≈20 wt % NaCl equiv) recorded in other magmatic-related polymetallic epithermal deposits worldwide. You do not have access to this content, please speak to your institutional administrator if you feel you should have access.