Geochemical Characteristics and Tectonic Significance of Early Carboniferous Volcanic Rocks of Kalamaili,Xinjiang |
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Authors: | Chen Wanfeng Guo Gang Miao Xiuquan Wang Jinrong Hu Wanlong Zhao Binbin Fan Lifei |
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Affiliation: | 1.Key Laboratory of Mineral Resources in Western China (Gansu Province), School of Earth Sciences, Lanzhou University, Lanzhou 730000, China; 2.Nonferrous Geological Prospecting Bureau of Geophysical Prospecting Team of Xinjiang, Urumqi 830011, China; 3.No.2 Geology and Exploration Team, Gansu Provincial Bureau of Geology and Mineral Exploration and Development, Lanzhou 730020, China; 4.Gansu Geological Survey Institute of Nonferrous Metal,Lanzhou 730000,China |
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Abstract: | Shanlianglishi Formation strata volcanic rocks are widely distributed in western fault zone of Kalamaili. Studies show that the rocks are basalt, andesite and basaltic andesite, calc-alkaline series with SiO2 content of samples ranging from 49.43% to 59.08%, TiO2 (1.18%~2.49%), P2O5 (0.21%~0.92%) and MgO (3.81%~6.28%). Samples have relatively high HFSE content (Ti, Zr, Y) and also high La/Nb (2.98~1.96), Zr/Y (9.36~4.01) ratio. The primitive mantle normalized trace element spider shows samples enriched LILE (Rb, Ba, K, U) and Pb, but relatively depleted Nb, Ta and Ti. Rare earth element distribution of REE shows slightly enriched LREE, (La/Yb)N=1.93~9.59, and that Eu is weakly negative anomaly (δEu=0.87~0.95). Combined with geochemical characteristics of WPB and VAB. Shanlianglishi Formation strata formed in the stretched after collision environmen. After partial melting of the enriched mantle that was previously metasomatized by the subduction fluid and with participation of the subduction sediment, magma experienced a certain degree of fractional crystallization and contamination by earth crust, and then erupted to form the Shanlianglishi Formation strata volcanic rocks. In eraly Late-Carboniferous, extensional movement was the most intense volcanic activity, which reached its peak in this area. |
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Keywords: | Shanlianglishi Formation strata Kalamaili Early-Carboniferous volcanic rocks Xinjiang. Post-collision |
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