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Molybdenum isotopic evidence for oxic marine conditions during the latest Permian extinction

Bernadette C. Proemse, Stephen E. Grasby, M. E. Wieser, B. Mayer and B. Beauchamp
Molybdenum isotopic evidence for oxic marine conditions during the latest Permian extinction
Geology (Boulder) (July 2013) 41 (9): 967-970

Abstract

The 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 (H (sub 2) S rich) conditions, from deep to shallow water environments, are commonly suggested. As a proxy for marine oxygen levels, we analyzed delta (super 98/95) Mo 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 delta (super 98/95) Mo values from -2.02 per mil to +2.23 per mil 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 per mil to +0.05 per mil), 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.


ISSN: 0091-7613
EISSN: 1943-2682
Coden: GLGYBA
Serial Title: Geology (Boulder)
Serial Volume: 41
Serial Issue: 9
Title: Molybdenum isotopic evidence for oxic marine conditions during the latest Permian extinction
Affiliation: University of Calgary, Department of Geoscience, Calgary, AB, Canada
Pages: 967-970
Published: 20130711
Text Language: English
Publisher: Geological Society of America (GSA), Boulder, CO, United States
References: 37
Accession Number: 2013-061458
Categories: StratigraphyIsotope geochemistry
Document Type: Serial
Bibliographic Level: Analytic
Annotation: GSA Data Repository item 2013272
Illustration Description: illus. incl. geol. sketch map
N76°00'00" - N84°00'00", W92°00'00" - W60°00'00"
Country of Publication: United States
Secondary Affiliation: GeoRef, Copyright 2017, American Geosciences Institute. Reference includes data from GeoScienceWorld, Alexandria, VA, United States. Reference includes data supplied by the Geological Society of America, Boulder, CO, United States
Update Code: 201337
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