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Tytuł pozycji:

Changes in depth-transect redox conditions spanning the end-Permian mass extinction and their impact on the marine extinction: Evidence from biomarkers and sulfur isotopes

Tytuł:
Changes in depth-transect redox conditions spanning the end-Permian mass extinction and their impact on the marine extinction: Evidence from biomarkers and sulfur isotopes
Autorzy:
Kaiho, Kunio
Oba, Masahiro
Fukuda, Yoshihiko
Ito, Kosuke
Ariyoshi, Shun
Gorjan, Paul
Riu, Yuqing
Takahashi, Satoshi
Chen, Zhong-Qiang
Tong, Jinnan
Yamakita, Satoshi
Temat:
*Mass extinctions
*Soil mapping
*Biomarkers
Spanning trees
Permian Period
Sulfur isotopes
Źródło:
Global & Planetary Change. Aug2012, Vol. 94-95, p20-32. 13p.
Czasopismo naukowe
Abstract: Changes in redox conditions during the Changhsingian to Griesbachian spanning the end-Permian mass extinction were recently reported based on analyses of organic molecules. We provide more precise organic-molecular data, that detail redox conditions spanning the end-Permian mass extinction at different palaeowater depths in the neritic Palaeotethys (estimated water depths: 10, 40, 100, and 200m; Bulla, Huangzhishan, Meishan, and Chaohu sections, respectively) during this period. Here we propose that a change from occasional euxinia to anoxia in the shallow Palaeotethys occurred at the time of the mass extinction intercalated with oxic pulses. The second extinction at 0.7myr after the main extinction was also caused by anoxia. New and published sulfur-isotope ratios (34S/32S) measured in carbonate-associated sulfate from the neritic Palaeotethys and in sulfide from pelagic central Panthalassa sediments show high values during the Changhsingian, consistent with the development of euxinia. The mass extinction coincided with a global fall in δ34S values, as well as a shift in δ13C values, indicating a global oxidation of H2S. This organic and isotopic geochemistry implies that accumulation of hydrogen sulfide in intermediate and deep waters followed by oxidation of hydrogen sulfide led to dissolved oxygen consumption, surface-water anoxia, and acidification, resulting in the end-Permian mass extinction in the seas. [Copyright &y& Elsevier]
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