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Persistent oceanic anoxia and elevated extinction rates separate the Cambrian and Ordovician radiations

2015; Geological Society of America; Volume: 43; Issue: 9 Linguagem: Inglês

10.1130/g36814.1

1943-2682

Matthew R. Saltzman, Cole T. Edwards, Jonathan M. Adrain, Stephen R. Westrop,

Geology and Paleoclimatology Research

Research Article| September 01, 2015 Persistent oceanic anoxia and elevated extinction rates separate the Cambrian and Ordovician radiations Matthew R. Saltzman; Matthew R. Saltzman * 1School of Earth Sciences, The Ohio State University, Columbus, Ohio 43210, USA *E-mail: saltzman.11@osu.edu Search for other works by this author on: GSW Google Scholar Cole T. Edwards; Cole T. Edwards 1School of Earth Sciences, The Ohio State University, Columbus, Ohio 43210, USA2Department of Earth and Planetary Sciences, Washington University, Saint Louis, Missouri 63130, USA Search for other works by this author on: GSW Google Scholar Jonathan M. Adrain; Jonathan M. Adrain 3Department of Earth & Environmental Sciences, University of Iowa, Iowa City, Iowa 52242, USA Search for other works by this author on: GSW Google Scholar Stephen R. Westrop Stephen R. Westrop 4Sam Noble Oklahoma Museum of Natural History and ConocoPhillips School of Geology & Geophysics, University of Oklahoma, Norman, Oklahoma 73072, USA Search for other works by this author on: GSW Google Scholar Author and Article Information Matthew R. Saltzman * 1School of Earth Sciences, The Ohio State University, Columbus, Ohio 43210, USA Cole T. Edwards 1School of Earth Sciences, The Ohio State University, Columbus, Ohio 43210, USA2Department of Earth and Planetary Sciences, Washington University, Saint Louis, Missouri 63130, USA Jonathan M. Adrain 3Department of Earth & Environmental Sciences, University of Iowa, Iowa City, Iowa 52242, USA Stephen R. Westrop 4Sam Noble Oklahoma Museum of Natural History and ConocoPhillips School of Geology & Geophysics, University of Oklahoma, Norman, Oklahoma 73072, USA *E-mail: saltzman.11@osu.edu Publisher: Geological Society of America Received: 24 Mar 2015 Revision Received: 24 Jun 2015 Accepted: 05 Jul 2015 First Online: 09 Mar 2017 Online ISSN: 1943-2682 Print ISSN: 0091-7613 © 2015 Geological Society of America Geology (2015) 43 (9): 807–810. https://doi.org/10.1130/G36814.1 Article history Received: 24 Mar 2015 Revision Received: 24 Jun 2015 Accepted: 05 Jul 2015 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 Matthew R. Saltzman, Cole T. Edwards, Jonathan M. Adrain, Stephen R. Westrop; Persistent oceanic anoxia and elevated extinction rates separate the Cambrian and Ordovician radiations. Geology 2015;; 43 (9): 807–810. doi: https://doi.org/10.1130/G36814.1 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 Recurrent mass extinction events (at "biomere"—a biostratigraphic unit—boundaries) characterize the middle Cambrian to Early Ordovician (Tremadocian) time interval that is between the major Cambrian and Ordovician radiations of animal life. A role for anoxia in maintaining elevated extinction rates in the late Cambrian has been proposed based on coincidence of an extinction with positive excursions in δ13Ccarb and δ34SCAS (CAS—carbonate-associated sulfate). Here we examine an Early Ordovician extinction event at the base of the North American Stairsian Stage (upper Tremadocian), and demonstrate concurrent onset of positive excursions in δ13C and δ34S inferred to reflect enhanced organic matter burial under anoxic waters. Sea-level rise may have brought anoxic waters onto the shelf to initiate extinctions. The evidence for δ13C excursions and elevated extinction rates appears to wane in the Tremadocian, consistent with progressive oxygenation of the oceans reaching a threshold that helped facilitate initial stages of the Great Ordovician Biodiversification Event. You do not have access to this content, please speak to your institutional administrator if you feel you should have access.