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Onset of main Phanerozoic marine radiation sparked by emerging Mid Ordovician icehouse.

Author:
  • Christian Rasmussen
  • Clemens V Ullmann
  • Kristian G Jakobsen
  • Anders Lindskog
  • Jesper Hansen
  • Thomas Hansen
  • Mats Eriksson
  • Andrei Dronov
  • Robert Frei
  • Christoph Korte
  • Arne T Nielsen
  • David A T Harper
Publishing year: 2016
Language: English
Publication/Series: Scientific Reports
Volume: 6
Document type: Journal article
Publisher: Nature Publishing Group

Abstract english

The Great Ordovician Biodiversification Event (GOBE) was the most rapid and sustained increase in marine Phanerozoic biodiversity. What generated this biotic response across Palaeozoic seascapes is a matter of debate; several intrinsic and extrinsic drivers have been suggested. One is Ordovician climate, which in recent years has undergone a paradigm shift from a text-book example of an extended greenhouse to an interval with transient cooling intervals - at least during the Late Ordovician. Here, we show the first unambiguous evidence for a sudden Mid Ordovician icehouse, comparable in magnitude to the Quaternary glaciations. We further demonstrate the initiation of this icehouse to coincide with the onset of the GOBE. This finding is based on both abiotic and biotic proxies obtained from the most comprehensive geochemical and palaeobiological dataset yet collected through this interval. We argue that the icehouse conditions increased latitudinal and bathymetrical temperature and oxygen gradients initiating an Early Palaeozoic Great Ocean Conveyor Belt. This fuelled the GOBE, as upwelling zones created new ecospace for the primary producers. A subsequent rise in δ(13)C ratios known as the Middle Darriwilian Isotopic Carbon Excursion (MDICE) may reflect a global response to increased bioproductivity encouraged by the onset of the GOBE.

Keywords

  • Geology

Other

Published
  • Early–Middle Ordovician biotic and sedimentary dynamics in the Baltoscandian paleobasin
  • ISSN: 2045-2322
Mats Eriksson
E-mail: mats [dot] eriksson [at] geol [dot] lu [dot] se

Professor

Lithosphere and Biosphere Science

+46 46 222 96 02

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