ZIRCON COMPOSITIONAL EVIDENCE FOR SULFUR-DEGASSING FROM ORE-FORMING ARC MAGMAS

Abstract

Research Article| January 01, 2015 ZIRCON COMPOSITIONAL EVIDENCE FOR SULFUR-DEGASSING FROM ORE-FORMING ARC MAGMAS* John H. Dilles; John H. Dilles † 1College of Earth, Ocean, and Atmospheric Sciences, Oregon State University, Corvallis, Oregon 97331-5501 †Corresponding author: e-mail, dillesj@science.oregonstate.edu Search for other works by this author on: GSW Google Scholar Adam J.R. Kent; Adam J.R. Kent 1College of Earth, Ocean, and Atmospheric Sciences, Oregon State University, Corvallis, Oregon 97331-5501 Search for other works by this author on: GSW Google Scholar Joseph L. Wooden; Joseph L. Wooden 2School of Earth Sciences, Stanford University, Stanford, California 94305-2210 Search for other works by this author on: GSW Google Scholar Richard M. Tosdal; Richard M. Tosdal 3MDRU, Department of Earth and Ocean Sciences, University of British Columbia, Vancouver, British Columbia, Canada V6T 1Z4 Search for other works by this author on: GSW Google Scholar Alison Koleszar; Alison Koleszar 1College of Earth, Ocean, and Atmospheric Sciences, Oregon State University, Corvallis, Oregon 97331-5501 Search for other works by this author on: GSW Google Scholar Robert G. Lee; Robert G. Lee 1College of Earth, Ocean, and Atmospheric Sciences, Oregon State University, Corvallis, Oregon 97331-5501 Search for other works by this author on: GSW Google Scholar Lucian P. Farmer Lucian P. Farmer 1College of Earth, Ocean, and Atmospheric Sciences, Oregon State University, Corvallis, Oregon 97331-5501 Search for other works by this author on: GSW Google Scholar Author and Article Information John H. Dilles † 1College of Earth, Ocean, and Atmospheric Sciences, Oregon State University, Corvallis, Oregon 97331-5501 Adam J.R. Kent 1College of Earth, Ocean, and Atmospheric Sciences, Oregon State University, Corvallis, Oregon 97331-5501 Joseph L. Wooden 2School of Earth Sciences, Stanford University, Stanford, California 94305-2210 Richard M. Tosdal 3MDRU, Department of Earth and Ocean Sciences, University of British Columbia, Vancouver, British Columbia, Canada V6T 1Z4 Alison Koleszar 1College of Earth, Ocean, and Atmospheric Sciences, Oregon State University, Corvallis, Oregon 97331-5501 Robert G. Lee 1College of Earth, Ocean, and Atmospheric Sciences, Oregon State University, Corvallis, Oregon 97331-5501 Lucian P. Farmer 1College of Earth, Ocean, and Atmospheric Sciences, Oregon State University, Corvallis, Oregon 97331-5501 †Corresponding author: e-mail, dillesj@science.oregonstate.edu Publisher: Society of Economic Geologists Received: 22 Aug 2013 Accepted: 15 May 2014 First Online: 09 Mar 2017 Online ISSN: 1554-0774 Print ISSN: 0361-0128 © 2015 Society of Economic Geologists. Economic Geology (2015) 110 (1): 241–251. https://doi.org/10.2113/econgeo.110.1.241 Article history Received: 22 Aug 2013 Accepted: 15 May 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 John H. Dilles, Adam J.R. Kent, Joseph L. Wooden, Richard M. Tosdal, Alison Koleszar, Robert G. Lee, Lucian P. Farmer; ZIRCON COMPOSITIONAL EVIDENCE FOR SULFUR-DEGASSING FROM ORE-FORMING ARC MAGMAS. Economic Geology 2015;; 110 (1): 241–251. doi: https://doi.org/10.2113/econgeo.110.1.241 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 Porphyry Cu (±Mo ±Au) and epithermal Au-Ag deposits are major sources of mined metals and are commonly formed by magmatic-hydrothermal fluids derived from hydrous magmas in Phanerozoic convergent margin settings. The igneous rock assemblages associated with porphyry mineral deposits are common in modern convergent margin settings, but while many have produced acidic magmatic fluids, very few, past or present, have produced sufficient metal, chlorine, and sulfur enrichments necessary to engender an ore deposit. The reasons for this remain uncertain.We report SHRIMP-RG ion microprobe analyses of hafnium, titanium and rare earth element (REE) abundances in zircon, a nearly ubiquitous and robust trace mineral in crustal magmas. Comparison of the compositions of zircons in ore-forming and barren granitic plutons indicate that ore-forming granites crystallized at relatively low temperature and have relatively small negative europium anomalies (mostly EuN/EuN* ≥0.4). We interpret these small zircon europium anomalies to indicate oxidizing magmatic conditions and hypothesize that in many cases this reflects oxidation due to SO2 degassing from magmas with a relatively low Fe/S ratio. Oxidation of europium and iron in the melt is produced by reduction of magmatic sulfate (S6+) to SO2 (S4+) upon degassing. This interpretation reinforces the important role of oxidized sulfur-rich fluids in porphyry and epithermal mineral deposit formation. Zircon compositions thus may be used to identify ancient magmas that released significant amounts of SO2-rich gases, and regional surveys of zircon composition are potentially a valuable tool for mineral exploration. You do not have access to this content, please speak to your institutional administrator if you feel you should have access.