Global-ocean redox variation during the middle-late Permian through Early Triassic based on uranium isotope and Th/U trends of marine carbonates

Abstract

Research Article| February 01, 2017 Global-ocean redox variation during the middle-late Permian through Early Triassic based on uranium isotope and Th/U trends of marine carbonates Maya Elrick; Maya Elrick 1Department of Earth and Planetary Sciences, University of New Mexico, Albuquerque, New Mexico 87131, USA Search for other works by this author on: GSW Google Scholar Victor Polyak; Victor Polyak 1Department of Earth and Planetary Sciences, University of New Mexico, Albuquerque, New Mexico 87131, USA Search for other works by this author on: GSW Google Scholar Thomas J. Algeo; Thomas J. Algeo 2Department of Geology, University of Cincinnati, Cincinnati, Ohio 45221-0013, USA3State Key Laboratory of Geological Processes and Mineral Resources, China University of Geosciences, Wuhan, Hubei 430074, China4State Key Laboratory of Biogeology and Environmental Geology, China University of Geosciences, Wuhan, Hubei 430074, China Search for other works by this author on: GSW Google Scholar Stephen Romaniello; Stephen Romaniello 5School of Earth and Space Exploration and Department of Chemistry and Biochemistry, Arizona State University, Tempe, Arizona 85287, USA Search for other works by this author on: GSW Google Scholar Yemane Asmerom; Yemane Asmerom 1Department of Earth and Planetary Sciences, University of New Mexico, Albuquerque, New Mexico 87131, USA Search for other works by this author on: GSW Google Scholar Achim D. Herrmann; Achim D. Herrmann 6Coastal Studies Institute and Department of Geology and Geophysics, Louisiana State University, Baton Rouge, Louisiana 70803, USA Search for other works by this author on: GSW Google Scholar Ariel D. Anbar; Ariel D. Anbar 5School of Earth and Space Exploration and Department of Chemistry and Biochemistry, Arizona State University, Tempe, Arizona 85287, USA Search for other works by this author on: GSW Google Scholar Laishi Zhao; Laishi Zhao 3State Key Laboratory of Geological Processes and Mineral Resources, China University of Geosciences, Wuhan, Hubei 430074, China Search for other works by this author on: GSW Google Scholar Zhong-Qiang Chen Zhong-Qiang Chen 4State Key Laboratory of Biogeology and Environmental Geology, China University of Geosciences, Wuhan, Hubei 430074, China Search for other works by this author on: GSW Google Scholar Geology (2017) 45 (2): 163–166. https://doi.org/10.1130/G38585.1 Article history received: 09 Sep 2016 rev-recd: 09 Nov 2016 accepted: 10 Nov 2016 first online: 02 Jun 2017 Cite View This Citation Add to Citation Manager Share Icon Share Facebook Twitter LinkedIn MailTo Tools Icon Tools Get Permissions Search Site Citation Maya Elrick, Victor Polyak, Thomas J. Algeo, Stephen Romaniello, Yemane Asmerom, Achim D. Herrmann, Ariel D. Anbar, Laishi Zhao, Zhong-Qiang Chen; Global-ocean redox variation during the middle-late Permian through Early Triassic based on uranium isotope and Th/U trends of marine carbonates. Geology 2017;; 45 (2): 163–166. doi: https://doi.org/10.1130/G38585.1 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 Uranium isotopes (238U/235U) in carbonates, a proxy for global-ocean redox conditions owing to their redox sensitivity and long residence time in seawater, exhibit substantial variability in the Daxiakou section of south China from the upper-middle Permian through the mid-lower Triassic (∼9 m.y.). Middle and late Permian ocean redox conditions were similar to that of the modern ocean and were characterized by improving oxygenation in the ∼2 m.y. prior to the latest Permian mass extinction (LPME), countering earlier interpretations of sustained or gradually expanding anoxia during this interval. The LPME coincided with an abrupt negative shift of >0.5‰ in δ238U that signifies a rapid expansion of oceanic anoxia. Intensely anoxic conditions persisted for at least ∼700 k.y. (Griesbachian), lessening somewhat during the Dienerian. Th/U concentration ratios vary inversely with δ238U during the Early Triassic, with higher ratios reflecting reduced U concentrations in global seawater as a consequence of large-scale removal to anoxic facies. Modeling suggests that 70%–100% of marine U was removed to anoxic sinks during the Early Triassic, resulting in seawater U concentrations of <5% that of the modern ocean. Rapid intensification of anoxia concurrent with the LPME implies that ocean redox changes played an important role in the largest mass extinction event in Earth history. You do not have access to this content, please speak to your institutional administrator if you feel you should have access.