Sulfur isotopic evidence for chemocline upward excursions during the end-Permian mass extinction

Anthony L. Riccardi, Michael A. Arthur, Lee R. Kump

Research output: Contribution to journalArticle

127 Scopus citations

Abstract

The latest Permian was a time of major change in ocean chemistry, accompanying the greatest mass extinction of the Phanerozoic. To examine the nature of these changes, samples from two well-studied marine sections that span the Permian-Triassic boundary have been analyzed: the Meishan and Shangsi sections located in Southern China. Isotopic analysis of the carbonate-associated sulfate in these samples provides a detailed record of several isotopic shifts in δ34SCAS approaching and across the PTB, ranging from +30 to -15‰ (VCDT), with repeated asynchronous fluctuations at the two locations. We interpret the patterns of isotopic shifts, in conjunction with other data, to indicate a shallow unstable chemocline overlying euxinic deep-water which periodically upwelled into the photic zone. These chemocline upward excursion events introduced sulfide to the photic zone stimulating a bloom of phototrophic sulfur oxidizing bacteria. We hypothesize that elemental sulfur globules produced by these organisms and 34S-depleted pyrite produced in the euxinic water column were deposited in the sediment; later oxidation led to incorporation as CAS. This created the large changes to the δ34SCAS observed in the latest Permian at these locations.

Original languageEnglish (US)
Pages (from-to)5740-5752
Number of pages13
JournalGeochimica et Cosmochimica Acta
Volume70
Issue number23 SPEC. ISS.
DOIs
StatePublished - Dec 1 2006

All Science Journal Classification (ASJC) codes

  • Geochemistry and Petrology

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