Petrogenesis and sedimentary environment of silicate in Late Paleozoic in Kala area of Western Sichuan Province |
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Authors: | LIU Daming YAO Hongyou HU Lin YU Liang LIU Yizhong |
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Institution: | 1. Northwest Sichuan Geological Team, Sichuan Geology and Mineral Bureau, Mianyang 621000, China;2. College of Earth Sciences, Chengdu University of Technology, Chengdu 610059, China |
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Abstract: | In order to study the sedimentary environment characteristics of the Late Paleozoic in Kala area of Western Sichuan Province, the authors have conducted the petrological and geochemical analyses of the widely distributed silicate in Qiongyi Formation of Lower Carboniferous and Kawenggou Formation of Upper Permian. The results show that the silicate in the study area belongs to the pure siliceous rocks, with a continuous supply of land-based materials during the deposition process. The average Al/(Al+Fe+Mn) ratio is 0.62, and the silicate shows a biogenic origin by the Al-Fe-Mn diagram. The ratios of Al2O3/ (Al2O3+ Fe2O3), Th/U, Th/Sc, (La/Ce)N and (La/Yb)N and tectonic environment discriminant diagram demonstrate that the silicate developed in a shallow-slope depesitional environment in the continental margin. The Ceanom value is -0.04 to 0.07, and it gradually increases from the Carboniferous to the Permian period, indicating the water body is in an anoxic environment with gradually increasing reducibility. The Garz--Litang basin opened in the Carboniferous period, in accordance with the regional geological evolution, and it continued to expand during the Permian period, with the gradually increasing depth of the seawater within the sedimentary basins. |
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Keywords: | Kala area of Western Sichuan Province silicate origin sedimentary environment |
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