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

Research output: Contribution to journalArticle

Abstract

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.

Details

Authors
  • 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
Organisations
External organisations
  • University of Copenhagen
Research areas and keywords

Subject classification (UKÄ) – MANDATORY

  • Geology
Original languageEnglish
Article number18884
JournalScientific Reports
Volume6
Publication statusPublished - 2016
Publication categoryResearch
Peer-reviewedYes

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