Sulfur isotopes of host strata for Howards Pass (Yukon–Northwest Territories) Zn-Pb deposits implicate anaerobic oxidation of methane, not basin stagnation

Abstract

Research Article| June 07, 2018 Sulfur isotopes of host strata for Howards Pass (Yukon–Northwest Territories) Zn-Pb deposits implicate anaerobic oxidation of methane, not basin stagnation Craig A. Johnson; Craig A. Johnson 1U.S. Geological Survey, P.O. Box 25046, Denver, Colorado 80225, USA Search for other works by this author on: GSW Google Scholar John F. Slack; John F. Slack * 2U.S. Geological Survey, National Center, MS 954, Reston, Virginia 20192, USA *Emeritus Search for other works by this author on: GSW Google Scholar Julie A. Dumoulin; Julie A. Dumoulin 3U.S. Geological Survey, Alaska Science Center, Anchorage, Alaska 99508, USA Search for other works by this author on: GSW Google Scholar Karen D. Kelley; Karen D. Kelley 1U.S. Geological Survey, P.O. Box 25046, Denver, Colorado 80225, USA Search for other works by this author on: GSW Google Scholar Hendrik Falck Hendrik Falck 4Northwest Territories Geological Survey, P.O. Box 1320, Yellowknife, NT X1A 2L9, Canada Search for other works by this author on: GSW Google Scholar Author and Article Information Craig A. Johnson 1U.S. Geological Survey, P.O. Box 25046, Denver, Colorado 80225, USA John F. Slack * 2U.S. Geological Survey, National Center, MS 954, Reston, Virginia 20192, USA Julie A. Dumoulin 3U.S. Geological Survey, Alaska Science Center, Anchorage, Alaska 99508, USA Karen D. Kelley 1U.S. Geological Survey, P.O. Box 25046, Denver, Colorado 80225, USA Hendrik Falck 4Northwest Territories Geological Survey, P.O. Box 1320, Yellowknife, NT X1A 2L9, Canada *Emeritus Publisher: Geological Society of America Received: 14 Mar 2018 Revision Received: 24 May 2018 Accepted: 25 May 2018 First Online: 07 Jun 2018 Online Issn: 1943-2682 Print Issn: 0091-7613 © 2018 Geological Society of America Geology (2018) 46 (7): 619–622. https://doi.org/10.1130/G40274.1 Article history Received: 14 Mar 2018 Revision Received: 24 May 2018 Accepted: 25 May 2018 First Online: 07 Jun 2018 Cite View This Citation Add to Citation Manager Share Icon Share Facebook Twitter LinkedIn MailTo Tools Icon Tools Get Permissions Search Site Citation Craig A. Johnson, John F. Slack, Julie A. Dumoulin, Karen D. Kelley, Hendrik Falck; Sulfur isotopes of host strata for Howards Pass (Yukon–Northwest Territories) Zn-Pb deposits implicate anaerobic oxidation of methane, not basin stagnation. Geology 2018;; 46 (7): 619–622. doi: https://doi.org/10.1130/G40274.1 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 A new sulfur isotope stratigraphic profile has been developed for Ordovician-Silurian mudstones that host the Howards Pass Zn-Pb deposits (Canada) in an attempt to reconcile the traditional model of a stagnant euxinic basin setting with new contradictory findings. Our analyses of pyrite confirm the up-section 34S enrichment reported previously, but additional observations show parallel depletion of carbonate 13C, an increase in organic carbon weight percent, and a change in pyrite morphology. Taken together, the data suggest that the 34S enrichment reflects a transition in the mechanism of pyrite formation during diagenesis, not isotopic evolution of a stagnant water mass. Low in the stratigraphic section, pyrite formed mainly in the sulfate reduction zone in association with organic matter–driven bacterial sulfate reduction. In contrast, starting just below the Zn-Pb mineralized horizon, pyrite formed increasingly within the sulfate-methane transition zone in association with anaerobic oxidation of methane. Our new insights on diagenesis have implications for (1) the setting of Zn-Pb ore formation, (2) the reliability of redox proxies involving metals, and (3) the source of ore sulfur for Howards Pass, and potentially for other stratiform Zn-Pb deposits contained in carbonaceous strata. You do not have access to this content, please speak to your institutional administrator if you feel you should have access.