Constraints on early Cambrian carbon cycling from the duration of the Nemakit-Daldynian–Tommotian boundary δ13C shift, Morocco

Abstract

Research Article| July 01, 2010 Constraints on early Cambrian carbon cycling from the duration of the Nemakit-Daldynian–Tommotian boundary δ13C shift, Morocco Adam C. Maloof; Adam C. Maloof 1Department of Geosciences, Princeton University, Princeton, New Jersey 08544, USA Search for other works by this author on: GSW Google Scholar Jahandar Ramezani; Jahandar Ramezani 2Department of Earth, Atmospheric and Planetary Sciences, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, USA Search for other works by this author on: GSW Google Scholar Samuel A. Bowring; Samuel A. Bowring 2Department of Earth, Atmospheric and Planetary Sciences, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, USA Search for other works by this author on: GSW Google Scholar David A. Fike; David A. Fike 3Department of Earth and Planetary Sciences, Washington University, St. Louis, Missouri 63130, USA Search for other works by this author on: GSW Google Scholar Susannah M. Porter; Susannah M. Porter 4Department of Earth Science, University of California–Santa Barbara, Santa Barbara, California 93106, USA Search for other works by this author on: GSW Google Scholar Mohamed Mazouad Mohamed Mazouad 5Département de Géologie, Université Hassan II, Casablanca, Morocco Search for other works by this author on: GSW Google Scholar Author and Article Information Adam C. Maloof 1Department of Geosciences, Princeton University, Princeton, New Jersey 08544, USA Jahandar Ramezani 2Department of Earth, Atmospheric and Planetary Sciences, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, USA Samuel A. Bowring 2Department of Earth, Atmospheric and Planetary Sciences, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, USA David A. Fike 3Department of Earth and Planetary Sciences, Washington University, St. Louis, Missouri 63130, USA Susannah M. Porter 4Department of Earth Science, University of California–Santa Barbara, Santa Barbara, California 93106, USA Mohamed Mazouad 5Département de Géologie, Université Hassan II, Casablanca, Morocco Publisher: Geological Society of America Received: 28 Sep 2009 Revision Received: 12 Jan 2010 Accepted: 08 Feb 2010 First Online: 09 Mar 2017 Online ISSN: 1943-2682 Print ISSN: 0091-7613 © 2010 Geological Society of America Geology (2010) 38 (7): 623–626. https://doi.org/10.1130/G30726.1 Article history Received: 28 Sep 2009 Revision Received: 12 Jan 2010 Accepted: 08 Feb 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 Adam C. Maloof, Jahandar Ramezani, Samuel A. Bowring, David A. Fike, Susannah M. Porter, Mohamed Mazouad; Constraints on early Cambrian carbon cycling from the duration of the Nemakit-Daldynian–Tommotian boundary δ13C shift, Morocco. Geology 2010;; 38 (7): 623–626. doi: https://doi.org/10.1130/G30726.1 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 The Nemakit-Daldynian–Tommotian (ND-T) boundary marks the first appearance of metazoan reefs and calcite biomineralizers and is associated with the largest δ13C shift during the Phanerozoic Eon. Biological transitions in Earth history are often accompanied by excursions in the carbon isotopic composition (δ13C) of the ocean, where δ13C variability is interpreted to reflect changes in the global carbon cycle. The duration and thus rate of these δ13C anomalies are rarely known, making it difficult to constrain their possible causes and their relationship, if any, to biologic transitions. We report sedimentological and δ13C data from a new 2.5-km-thick section that spans the early Cambrian evolutionary "explosion" in the Moroccan Anti-Atlas Mountains. Three new zircon 206Pb-238U ages from tuffs within the stratigraphy constrain the timing of the ND-T boundary to 524.84 ± 0.09 Ma. Two of the tuffs exactly bracket the ND-T transition and constrain the duration of the −8‰ δ13C shift to 506 ± 126 k.y. With a simple box model, we explore a range of geochemical processes that could account for such a rapid ND-T δ13C shift, and conclude that metamorphic and/or volcanic fluxes of carbon may have been sustained at levels 4–16 times higher than today for millions of years. You do not have access to this content, please speak to your institutional administrator if you feel you should have access.