A Cenozoic-style scenario for the end-Ordovician glaciation

• Published in: Nature Communications
• Main Authors: Ghienne, Jean-François, Desrochers, André, Vandenbroucke, Thijs R.A., Achab, Aïcha, Asselin, Esther, Dabard, Marie-Pierre, Farley, Claude, Loi, Alfredo, Paris, Florentin, Wickson, Steven, Veizer, Jan
• Other Authors: Institut de physique du globe de Strasbourg (IPGS), Université de Strasbourg (UNISTRA)-Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS), University of Ottawa, Dept. of Geology, Marion Hall, Ottawa , ON, Canada, Géosystèmes - UMR 8217 (Géosystèmes), Université de Picardie Jules Verne (UPJV)-Centre National de la Recherche Scientifique (CNRS)-Université de Lille, Sciences et Technologies, Institut National de la Recherche Scientifique Québec (INRS), Geological Survey of Canada Québec (GSC Québec), Geological Survey of Canada - Office (GSC), Natural Resources Canada (NRCan)-Natural Resources Canada (NRCan), Géosciences Rennes (GR), Centre National de la Recherche Scientifique (CNRS)-Observatoire des Sciences de l'Univers de Rennes (OSUR)-Institut national des sciences de l'Univers (INSU - CNRS)-Université de Rennes 1 (UR1), Université de Rennes (UNIV-RENNES)-Université de Rennes (UNIV-RENNES), Dipartimento di Scienze Chimiche e Geologiche Centro Grandi Strumenti and INSTM unit, Università di Cagliari, NSERC; Insu SYSTER, ANR-12-BS06-0014,SeqStrat-Ice,Les glaciations du passé: leçons pour un modèle de stratigraphie séquentielle dédié aux systèmes glaciaires(2012)
• Format: Article in Journal/Newspaper
• Language: English
• Published: HAL CCSD 2014
• Subjects: [SDU]Sciences of the Universe [physics]; Ice Sheet
• Online Access: https://hal-insu.archives-ouvertes.fr/insu-01184742; https://hal-insu.archives-ouvertes.fr/insu-01184742/document; https://hal-insu.archives-ouvertes.fr/insu-01184742/file/Ghienne-natcom.pdf; https://doi.org/10.1038/ncomms5485

International audience The end-Ordovician was an enigmatic interval in the Phanerozoic, known for massiveglaciation potentially at elevated CO2 levels, biogeochemical cycle disruptions recorded aslarge isotope anomalies and a devastating extinction event. Ice-sheet volumes claimed to betwice those of the Last Glacial Maximum paradoxically coincided with oceans as warm astoday. Here we argue that some of these remarkable claims arise from undersampling ofincomplete geological sections that led to apparent temporal correlations within the relativelycoarse resolution capability of Palaeozoic biochronostratigraphy. We examine exceptionallycomplete sedimentary records from two, low and high, palaeolatitude settings. Theircorrelation framework reveals a Cenozoic-style scenario including three main glacial cyclesand higher-order phenomena. This necessitates revision of mechanisms for the end-Ordovician events, as the first extinction is tied to an early phase of melting, not to initialcooling, and the largest d13C excursion occurs during final deglaciation, not at the glacial apex.