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Molybdenum isotopic evidence for oxic marine conditions during the latest Permian extinction
journal contribution
posted on 2023-05-18, 06:52 authored by Bernadette ProemseBernadette Proemse, Grasby, SE, Wieser, ME, Mayer, B, Beauchamp, BThe latest Permian extinction (LPE), ca. 252 Ma, represents the most severe extinction event in Earth's history. The cause is still debated, but widespread marine anoxic to euxinic (H2S rich) conditions, from deep to shallow water environments, are commonly suggested. As a proxy for marine oxygen levels, we analyzed δ98/95Mo of two LPE sections that represent a gradient in water depth on the northwest margin of Pangea. Results from deep-water slope environments show a large shift in δ98/95Mo values from −2.02‰ to +2.23‰ at the extinction horizon, consistent with onset of euxinic conditions. In contrast, sub-storm wave base shelf environments show little change in the molybdenum isotopic composition (−1.34‰ to +0.05‰), indicating ongoing oxic conditions across the LPE. These results indicate that areas of the continental shelf of northwest Pangea underwent mass extinction under oxic conditions throughout the LPE event, and that shallow-water anoxia was therefore not a global phenomenon.
History
Publication title
GeologyVolume
41Issue
9Pagination
967-970ISSN
0091-7613Department/School
School of Natural SciencesPublisher
Geological Soc AmericaPlace of publication
Inc, Po Box 9140, Boulder, USA, Co, 80301-9140Rights statement
Copyright 2013 Geological Society of AmericaRepository Status
- Restricted