Osmium isotope evidence for the regulation of atmospheric CO2 by continental weathering

Abstract

Research Article| February 01, 2004 Osmium isotope evidence for the regulation of atmospheric CO2 by continental weathering Anthony S. Cohen; Anthony S. Cohen 1 Department of Earth Sciences, The Open University, Milton Keynes MK7 6AA, UK Search for other works by this author on: GSW Google Scholar Angela L. Coe; Angela L. Coe 1 Department of Earth Sciences, The Open University, Milton Keynes MK7 6AA, UK Search for other works by this author on: GSW Google Scholar Stephen M. Harding; Stephen M. Harding 1 Department of Earth Sciences, The Open University, Milton Keynes MK7 6AA, UK Search for other works by this author on: GSW Google Scholar Lorenz Schwark Lorenz Schwark 2Geologisches Institut, Universität zu Köln, Zülpicher Strasse 49a, D-50674 Köln, Germany Search for other works by this author on: GSW Google Scholar Geology (2004) 32 (2): 157–160. https://doi.org/10.1130/G20158.1 Article history received: 05 Sep 2003 rev-recd: 24 Oct 2003 accepted: 27 Oct 2003 first online: 03 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 Anthony S. Cohen, Angela L. Coe, Stephen M. Harding, Lorenz Schwark; Osmium isotope evidence for the regulation of atmospheric CO2 by continental weathering. Geology 2004;; 32 (2): 157–160. doi: https://doi.org/10.1130/G20158.1 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 long-term stability of Earth's climate throughout the Phanerozoic stands in marked contrast to the dramatic fluctuations that have taken place on time scales as short as a few years, reflecting the high efficiency of longer-term climate regulation through negative feedbacks. A fundamental mechanism is thought to involve control of CO2 in the ocean- atmosphere system through continental weathering, although unambiguous, high-resolution data supporting this hypothesis have hitherto not been available. Organic-rich mud rocks from Yorkshire, England, which were deposited during the Toarcian oceanic anoxic event (ca. 181 Ma, Early Jurassic), contain evidence of an exceptionally large excursion in the 187Os/188Os ratio of contemporaneous seawater, from ∼0.4 to ∼1.0. The most likely explanation for this excursion is that it resulted from a transient increase in global continental weathering rates of ∼400%–800%. The Os isotope excursion coincided with a well-documented global δ13C excursion of −6‰ that affected all the major biospheric reservoirs of the time. Higher mean global temperatures caused global chemical weathering rates to increase substantially, while, in turn, chemical weathering was very effective in reducing the elevated levels of atmospheric CO2 and the high temperatures to preexcursion levels. You do not have access to this content, please speak to your institutional administrator if you feel you should have access.