September Geology and GSA Today media ...(ones today consuming hydrogen sulfide th...)

Date:8/22/2008

ones today, consuming hydrogen sulfide that upwells into the photic zone. Accounting for the presence of these organisms in the surface ocean reduces the amount of hydrogen sulfide released to the atmosphere but does not prevent hydrogen sulfide eruption from the ocean. The end-Permian geologic record is consistent with the modeled distribution of hydrogen sulfide, supporting the notion that hydrogen sulfide and carbon dioxide toxicity may have provided the kill mechanism for this mass extinction.

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GSA Today Science Article

Understanding mechanisms for the end-Permian mass extinction and the protracted Early Triassic aftermath and recovery

David J. Bottjer, Dept. of Earth Sciences, University of Southern California, Los Angeles, California 90089-0740, USA. Pages 4-10.

The Permo-Triassic (P-T) extinction is generally recognized as the largest mass extinction in Earth's history, with estimates ranging upwards of 90% species extinction. Identifying a cause for this extinction has proven elusive, as historically various agents from sea level fall, to volcanism, to global oceanic anoxia, to deadly oceanic burps of H2S have been hypothesized. New paleobiological studies on the environmental distribution and ecological importance of brachiopods, benthic molluscs, and bryozoans across the P-T boundary support the hypothesis that stressful ocean conditions, primarily elevated H2S levels (euxinia), but also heightened CO2 concentrations, were the prime causes of the end-Permian mass extinction. These studies also further demonstrate that both the Late Permian interval preceding and the Early Triassic interval following this mass extinction were times of similarly aggravated environmental stress. In the low-diversity, long term Early Triassic recovery, huge numbers of benthic mollusks typically covered the seafloor. That a relatively few marine molluscs thrived during this time indicates a tolerance for some combination of mar
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Contact: Christa Stratton cstratton@geosociety.org 303-357-1093 Geological Society of America Source:Eurekalert

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