A Cenozoic-style scenario for the end-Ordovician glaciation

The end-Ordovician was an enigmatic interval in the Phanerozoic, known for massive glaciation potentially at elevated CO2 levels, biogeochemical cycle disruptions recorded as large isotope anomalies and a devastating extinction event. Ice-sheet volumes claimed to be twice those of the Last Glacial M...

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Bibliographic Details
Published in:Nature Communications
Main Authors: Ghienne, Jean-François, Desrochers, André, Vandenbroucke, Thijs, Achab, Aicha, Asselin, Ester, Dabard, Marie-Pierre, Farley, Claude, Loi, Alfredo, Paris, Florentin, Wickson, Steven, Veizer, Jan
Format: Article in Journal/Newspaper
Language:English
Published: 2014
Subjects:
Earth and Environmental Sciences
EARLY SILURIAN GLACIATION
SEA-LEVEL CHANGE
MASS EXTINCTION
ANTI-ATLAS
ENVIRONMENTAL-CHANGES
ISOTOPIC EVIDENCE
ANTICOSTI ISLAND
HIGH-RESOLUTION
CLIMATE-CHANGE
MOROCCO
Ice Sheet
Online Access:https://biblio.ugent.be/publication/6848045
http://hdl.handle.net/1854/LU-6848045
https://doi.org/10.1038/ncomms5485
https://biblio.ugent.be/publication/6848045/file/6853496
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Summary:The end-Ordovician was an enigmatic interval in the Phanerozoic, known for massive glaciation potentially at elevated CO2 levels, biogeochemical cycle disruptions recorded as large isotope anomalies and a devastating extinction event. Ice-sheet volumes claimed to be twice those of the Last Glacial Maximum paradoxically coincided with oceans as warm as today. Here we argue that some of these remarkable claims arise from undersampling of incomplete geological sections that led to apparent temporal correlations within the relatively coarse resolution capability of Palaeozoic biochronostratigraphy. We examine exceptionally complete sedimentary records from two, low and high, palaeolatitude settings. Their correlation framework reveals a Cenozoic-style scenario including three main glacial cycles and 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 initial cooling, and the largest delta C-13 excursion occurs during final deglaciation, not at the glacial apex.

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