Dynamic polar climates in a greenhouse world: Evidence from clumped isotope thermometry of Early Cretaceous belemnites

Abstract

Research Article| August 01, 2013 Dynamic polar climates in a greenhouse world: Evidence from clumped isotope thermometry of Early Cretaceous belemnites Gregory D. Price; Gregory D. Price 1School of Geography, Earth and Environmental Sciences, Plymouth University, Plymouth PL4 8AA, UK Search for other works by this author on: GSW Google Scholar Benjamin H. Passey Benjamin H. Passey 2Department of Earth and Planetary Sciences, Johns Hopkins University, Baltimore, Maryland 21218, USA Search for other works by this author on: GSW Google Scholar Geology (2013) 41 (8): 923–926. https://doi.org/10.1130/G34484.1 Article history received: 13 Feb 2013 rev-recd: 15 Apr 2013 accepted: 18 Apr 2013 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 Gregory D. Price, Benjamin H. Passey; Dynamic polar climates in a greenhouse world: Evidence from clumped isotope thermometry of Early Cretaceous belemnites. Geology 2013;; 41 (8): 923–926. doi: https://doi.org/10.1130/G34484.1 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 Sub-arctic Cretaceous (Berriasian–late Valanginian, ca. 145–134 Ma) marine temperatures obtained from fossil mollusks (belemnites) are determined using carbonate clumped isotope thermometry, an approach based on the “clumping” of 13C and 18O in the carbonate mineral lattice into bonds with each other. From our analyses we infer sub-arctic Early Cretaceous marine temperatures ranging from 10 °C to 20 °C. These possibly seasonally biased, warm sub-arctic temperatures are warmer than present mean summer water temperatures at 60–65°N and are therefore consistent with a warmer “greenhouse” world featuring a shallow (equable) latitudinal temperature gradient. Our combined temperature and δ18Obelemnite data imply seawater δ18O values that have a remarkably modern character in that they are similar to modern high-latitude seawater but more positive than modeled Cretaceous seawater. We identify a cooler late Valanginian interval (ca. 134 Ma) with temperatures consistent with polar regions a few degrees above freezing and also coincident with increased δ18O seawater values. Thus we find evidence of intervals when polar ice was unlikely, and also when polar ice was plausible. Both scenarios support the view of generally warm but dynamic polar climates during greenhouse intervals that were punctuated by periods of ice growth. You do not have access to this content, please speak to your institutional administrator if you feel you should have access.