Iodine to calcium ratios in marine carbonate as a paleo-redox proxy during oceanic anoxic events

Abstract

Research Article| December 01, 2010 Iodine to calcium ratios in marine carbonate as a paleo-redox proxy during oceanic anoxic events Zunli Lu; Zunli Lu * Department of Earth Sciences, University of Oxford, Parks Road, Oxford OX1 3PR, UK *E-mail: Zunli.Lu@earth.ox.ac.uk. Search for other works by this author on: GSW Google Scholar Hugh C. Jenkyns; Hugh C. Jenkyns Department of Earth Sciences, University of Oxford, Parks Road, Oxford OX1 3PR, UK Search for other works by this author on: GSW Google Scholar Rosalind E.M. Rickaby Rosalind E.M. Rickaby Department of Earth Sciences, University of Oxford, Parks Road, Oxford OX1 3PR, UK Search for other works by this author on: GSW Google Scholar Author and Article Information Zunli Lu * Department of Earth Sciences, University of Oxford, Parks Road, Oxford OX1 3PR, UK Hugh C. Jenkyns Department of Earth Sciences, University of Oxford, Parks Road, Oxford OX1 3PR, UK Rosalind E.M. Rickaby Department of Earth Sciences, University of Oxford, Parks Road, Oxford OX1 3PR, UK *E-mail: Zunli.Lu@earth.ox.ac.uk. Publisher: Geological Society of America Received: 23 Feb 2010 Revision Received: 07 Jul 2010 Accepted: 11 Jul 2010 First Online: 09 Mar 2017 Online ISSN: 1943-2682 Print ISSN: 0091-7613 © 2010 Geological Society of America Geology (2010) 38 (12): 1107–1110. https://doi.org/10.1130/G31145.1 Article history Received: 23 Feb 2010 Revision Received: 07 Jul 2010 Accepted: 11 Jul 2010 First Online: 09 Mar 2017 Cite View This Citation Add to Citation Manager Share Icon Share Facebook Twitter LinkedIn Email Permissions Search Site Citation Zunli Lu, Hugh C. Jenkyns, Rosalind E.M. Rickaby; Iodine to calcium ratios in marine carbonate as a paleo-redox proxy during oceanic anoxic events. Geology 2010;; 38 (12): 1107–1110. doi: https://doi.org/10.1130/G31145.1 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 Periods of globally distributed extreme oxygen depletion, so-called oceanic anoxic events (OAEs), have been recognized in the Mesozoic geological record and appear to be characteristic of episodes of extreme warmth. Here we explore the application of iodine/calcium ratios (I/Ca) in marine carbonate as a new geochemical proxy to constrain seawater redox change, and provide additional insights into the response of ocean chemistry to ancient climatic warming. Iodine has long been known as a redox-sensitive and biophilic element, mainly present as iodate and iodide in seawater, iodate converting to iodide under anoxic conditions. Laboratory experiments growing calcite crystals from solutions spiked with iodate show that this is the ionic species incorporated into the carbonate structure, likely substituting for the CO32− ion. A fall in the I/Ca ratio measured in carbonates formed in shallow water by marine calcifiers during the early Toarcian and Cenomanian-Turonian OAEs is interpreted both as a response to a decrease in the iodate/iodide ratio in ocean waters and the drawdown of the global iodine inventory under conditions of accelerated organic-matter burial. The results suggest that I/Ca ratios in carbonates may be used to monitor seawater oxidation levels throughout Earth history. You do not have access to this content, please speak to your institutional administrator if you feel you should have access.