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Proc Natl Acad Sci U S A. 2010 May 11;107(19):8543-8. doi: 10.1073/pnas.0914065107. Epub 2010 Apr 26.

Calcium isotope constraints on the end-Permian mass extinction.

Author information

1
Department of Geological and Environmental Sciences, Stanford University, Stanford, CA 94305, USA. jlpayne@stanford.edu

Abstract

The end-Permian mass extinction horizon is marked by an abrupt shift in style of carbonate sedimentation and a negative excursion in the carbon isotope (delta(13)C) composition of carbonate minerals. Several extinction scenarios consistent with these observations have been put forward. Secular variation in the calcium isotope (delta(44/40)Ca) composition of marine sediments provides a tool for distinguishing among these possibilities and thereby constraining the causes of mass extinction. Here we report delta(44/40)Ca across the Permian-Triassic boundary from marine limestone in south China. The delta(44/40)Ca exhibits a transient negative excursion of approximately 0.3 per thousand over a few hundred thousand years or less, which we interpret to reflect a change in the global delta(44/40)Ca composition of seawater. CO(2)-driven ocean acidification best explains the coincidence of the delta(44/40)Ca excursion with negative excursions in the delta(13)C of carbonates and organic matter and the preferential extinction of heavily calcified marine animals. Calcium isotope constraints on carbon cycle calculations suggest that the average delta(13)C of CO(2) released was heavier than -28 per thousand and more likely near -15 per thousand; these values indicate a source containing substantial amounts of mantle- or carbonate-derived carbon. Collectively, the results point toward Siberian Trap volcanism as the trigger of mass extinction.

PMID:
20421502
PMCID:
PMC2889361
DOI:
10.1073/pnas.0914065107
[Indexed for MEDLINE]
Free PMC Article

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