A Cenozoic-style scenario for the end-Ordovician glaciation
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 o...
Published in: | Nature Communications |
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Main Authors: | , , , , , , , , , , |
Other Authors: | , , , , , , , , , , , , , , , |
Format: | Article in Journal/Newspaper |
Language: | English |
Published: |
HAL CCSD
2014
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Subjects: | |
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 |
Summary: | 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. |
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