ペルム紀末大量絶滅時の硫化水素大量放出事変(<特集>顕生代の環境擾乱イベントとその解析)

概要

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Mass extinction of life at the end of the Permian ca. 250 million years ago was characterized by (1) abrupt and coincident extinctions in the ocean and on land during a period of only 10,000 years and (2) delay of ecosystem recovery during the following 10 million years encompassing the largest known turnover of marine and land biota. Previously suggested direct causes of this major event include gradual extreme warming, oceanic anoxia, a decrease in ozone by mass release of H_2S and CH_4, and gradual atmospheric hypoxia. A positive anomaly in the ^<34>S/^<32>S ratio of carbonate-associated sulfate (CAS) in uppermost Permian marine sediments implies that H_2S accumulated in the ocean during a period of 〜1 million years. The accumulation period was followed by massive release of H_2S (evidenced by a decrease in the ^<34>S/^<32>S ratio of CAS) coinciding with the mass extinction. Oxidation of the H_2S would have caused a significant decrease in atmospheric O_2. The hypoxia event occurred over a much shorter time period (10^4 years) than previously suggested (10^7 years) and can explain the rapidity of the major end-Permian mass extinction which triggered development of the Earth's modern biota.
日本有機地球化学会の論文
2008-12-30