| 中国煤山剖面二叠／三叠系事件界线地层中石膏的负硫同位素异常 |
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| 关键词:sulfur isotope gypsum Permian-Triassic Meishan section mass extinction |
| 基金项目:国家自然科学基金项目(40072055)，国土资源部重点科技项目(20010209) |
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| Evidence of Extremely Light Gypsum from the Permian-Triassic (P/T) Event Boundary at the Meishan Section of South China |
| There are famous "white clay" and "black clay" existing in the Permian Triassic (P/T) event boundary at the Meishan section that is located in Changxing County, Zhejiang Province of South China.This study focuses on detecting sulfur composition of the gypsum naturally trapped in both of the boundary clays, by isotopic mass spectrometry assistant with standard method of SF 6 preparation. To our surprise, the gypsum proves to have extraordinarily negative delta values, including -9.2‰ (δ 34 S V CDT ) or -4.6‰ (δ 33 S V CDT ) in average for the gypsum in euhedral crystal selected form the white clay, -10.7‰ or -5.5‰ for the whole gypsum water extracted from the same clay, and -15.6‰ or -8.2‰ for those water extracted from the black clay. To our know ledge, such extremely light sulfur dominated gypsum, which now offers the most negative anomaly of sulfur isotope ratio of sulfate towards the P/T event boundary at Meishan section, is originally recognized in this study, not only for the P/T sections but also for other mass extinction related boundary sections in the world. This finding would open a new window for insight into the P/T catastrophic event as well as its subsequent changes of environment in the past of the Earth. Furthermore, native Fe S nuggets close to the white clay are also determined to be usual isotopic composition in average values of +1.3‰ (δ 34 S V CDT ) and +0.7‰ ( δ 33 S V CDT ),and any trace of expecting organic genetic pyrites as well as their analogs fails to prove in our efforts, both of which probably excludes a possibility of organic genesis for the light gypsum we find. Thus, origin of this unexpected gypsum remains to be understood in future. |
| LIANG Han-dong,DING Ti-ping.2004.Evidence of Extremely Light Gypsum from the Permian-Triassic (P/T) Event Boundary at the Meishan Section of South China[J].Acta Geoscientica Sinica,25(1):33-37. |
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