Extreme Silver Isotope Variation in Orogenic Gold Systems Implies Multistaged Metal Remobilization During Ore Genesis

Research Article| March 01, 2019 Extreme Silver Isotope Variation in Orogenic Gold Systems Implies Multistaged Metal Remobilization During Ore Genesis Christopher R. Voisey; Christopher R. Voisey 1School of Earth, Atmosphere & Environment, Monash University, Clayton, VIC 3800, Australia †Corresponding author: e-mail, christopher.voisey@monash.edu Search for other works by this author on: GSW Google Scholar Roland Maas; Roland Maas 2School of Earth Sciences, Melbourne University, Melbourne, VIC3000, Australia Search for other works by this author on: GSW Google Scholar Andrew G. Tomkins; Andrew G. Tomkins 1School of Earth, Atmosphere & Environment, Monash University, Clayton, VIC 3800, Australia Search for other works by this author on: GSW Google Scholar Michael Brauns; Michael Brauns 3Curt-Engelhorn-Zentrum Archäometrie, Mannheim, Germany Search for other works by this author on: GSW Google Scholar Gerhard Brügmann Gerhard Brügmann 3Curt-Engelhorn-Zentrum Archäometrie, Mannheim, Germany Search for other works by this author on: GSW Google Scholar Author and Article Information Christopher R. Voisey 1School of Earth, Atmosphere & Environment, Monash University, Clayton, VIC 3800, Australia Roland Maas 2School of Earth Sciences, Melbourne University, Melbourne, VIC3000, Australia Andrew G. Tomkins 1School of Earth, Atmosphere & Environment, Monash University, Clayton, VIC 3800, Australia Michael Brauns 3Curt-Engelhorn-Zentrum Archäometrie, Mannheim, Germany Gerhard Brügmann 3Curt-Engelhorn-Zentrum Archäometrie, Mannheim, Germany †Corresponding author: e-mail, christopher.voisey@monash.edu Publisher: Society of Economic Geologists Accepted: 05 Jan 2019 First Online: 27 Mar 2019 Online Issn: 1554-0774 Print Issn: 0361-0128 © 2019 Economic GeologyEconomic Geology Economic Geology (2019) 114 (2): 233–242. https://doi.org/10.5382/econgeo.2019.4629 Article history Accepted: 05 Jan 2019 First Online: 27 Mar 2019 Cite View This Citation Add to Citation Manager Share Icon Share Facebook Twitter LinkedIn MailTo Tools Icon Tools Get Permissions Search Site Citation Christopher R. Voisey, Roland Maas, Andrew G. Tomkins, Michael Brauns, Gerhard Brügmann; Extreme Silver Isotope Variation in Orogenic Gold Systems Implies Multistaged Metal Remobilization During Ore Genesis. Economic Geology 2019;; 114 (2): 233–242. doi: https://doi.org/10.5382/econgeo.2019.4629 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 We report the first Ag isotope data for the Paleozoic orogenic Au deposits in the Victorian Goldfields, southeast Australia, a world-class province with a historic production of 2,400 tonnes of Au. Despite their relatively uniform geology—similar host-rock types, age, mineralization style—deposits in Victoria show a wide range in 107Ag/109Ag ratios in native Au (ε107Ag −6.6 to +8.3, relative to the NIST SRM 978a Ag standard), comparable to the entire previously known terrestrial range (−9.4 to +5.3). The data show no correlation with mineralization age or host-rock composition, and there is no obvious isotopic link to established "mantle" or "crustal" Ag isotope values, implying that source rock signatures are unlikely to be the main control on Ag isotope variations. Instead, it is suggested that the Ag isotope variation is primarily related to physicochemical processes, particularly Ag isotope fractionation during redox reactions such as conversion of Ag0 in native Au to Ag+ in dissolved Ag(HS)2− or sulfide-borne Ag. Repeated Ag0←→ Ag+ reactions along transport pathways and at sites of ore accumulation could generate a wide range in ε107Ag, and evidence of this range is presented in the data here. Silver isotope fractionation via numerous deposition-dissolution cycles provides a different perspective into large-scale ore genesis that has not previously been recognized for orogenic gold systems; multistaged metal remobilization along fluid transport pathways is standard during their formation. Detailed Ag isotope studies have considerable potential for understanding the history of episodic metal addition and within-deposit redistribution. You do not have access to this content, please speak to your institutional administrator if you feel you should have access.