Discovery of an abnormally high-δ34S barite deposit and a new understanding of global sulfur isotope variation during geological history |
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作者姓名: | GAO Junbo YANG Ruidong TAO Ping CHENG Wei WEI Huairui |
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作者单位: | College of Resources and Environmental Engineering, Guizhou University;Geological Survey of Guizhou Academy of Sciences |
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基金项目: | funded by the Ph. D. Foundation of Ministry of Education of China (20105201110002);the Foundation of Governor of Guizhou Province (2009179);the Joint Research Program Funded by Doctoral Discipline Construction of Guizhou University and Guizhou Geology and Mineral Exploitation and Development Bureau |
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摘 要: | The evolution of the global sulfur isotope curve was plotted based on the δ34S values of evaporates resultant from oceanic evaporation. In the long period of geological history the δ34S values showed obvious peaks for three times during the process of ancient oceans’ sulfur isotope evolution, namely the Early Cambrian (+30‰), the Late Devonian (+25‰) and the Permian-Triassic transition interval (+17‰), but the causes of the abnormal rise of sulfur isotopic values during the geological period are still in question. In this paper, 18 samples collected from a large Devonian barite deposit from Zhenning County were analyzed to determine their δ34S values, revealing that the 18 samples have very high δ34S values (δ34S=41.88‰-+68.39‰), with an average close to 56.30‰, which are higher than the isotopic values of contemporary sulfates (+17‰- +25‰). A comparative analysis was conducted of the emerging of high δ34S barite deposits (from Cambrian and Devonian) and the δ34S variation curves of the ancient oceans. The results indicate that the time when the obvious peaks of δ34S values appeared and the time of massive sedimentation of high δ34S barite deposits are very close to each other, which, in our opinion, is not a coincidence. There may exist some correlations between the sulfur isotope evolution of ancient oceans during the diverse periods of geological history and the massive sedimentation of high δ34S barite deposits. Therefore, it is inferred that perhaps it was the massive sedimentation of high δ34S barites that caused the sharp rise of δ34S values in a short period of time.
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关 键 词: | global sulfur isotopic variation δ34S value barite Devonian Guizhou |
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