Petrogenesis of volcanic rocks in the Sangxiu Formation,central segment of Tethyan Himalaya: A probable example of plume–lithosphere interaction |
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| Institution: | 1. Guangdong Provincal Key Lab of Geodynamics and Geohazards, School of Earth Sciences and Engineering, Sun Yat-sen University, Guangzhou 510275, China;2. State Key Laboratory of Lithospheric Evolution, Institute of Geology and Geophysics, Chinese Academy of Sciences, Beijing 100029, China;1. State Key Laboratory of Lithospheric Evolution, Institute of Geology and Geophysics, Chinese Academy of Sciences, Beijing 100029, China;2. Department of Earth and Environmental Sciences, Università di Milano-Bicocca, 20126 Milan, Italy;3. State Key Laboratory of Mineral Deposits Research, School of Earth Sciences and Engineering, Nanjing University, Nanjing 210023, China;4. School of Earth Science and Geological Engineering, Sun Yat-sen University, Guangzhou 510275, China;1. Key Laboratory of Continental Collision and Plateau Uplift, Institute of Tibetan Plateau Research, Chinese Academy of Sciences, Beijing 100101, China;2. University of Chinese Academy of Sciences, Beijing 100049, China;3. Chinese Academy of Sciences Center for Excellence in Tibetan Plateau Earth Sciences, Beijing 100101, China;4. Department of Geosciences, Auburn University, Auburn, AL 36849, USA;1. School of Earth Sciences and Resources, China University of Geosciences, Beijing 100083, PR China;2. Institute of Geology, Chinese Academy of Geological Sciences, Beijing 100037, PR China |
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| Abstract: | The ～133 Ma volcanic rocks of Sangxiu Formation are distributed in the eastern part of the central Tethyan Himalaya and belong paleogeographically to the northeastern margin of Greater India. These volcanic rocks include alkaline basalts and felsic volcanic rocks. Major and trace element abundances and whole-rock isotopic data for selected samples of these volcanic rocks are used to infer their petrogenesis. Geochemically, the Sangxiu basalts are closely similar to the Emeishan high-Ti basalts. Major and trace element data and Sr–Nd isotopic compositions suggest that the Sangxiu basalts may have been derived from an OIB-type mantle source, with discernable contributions from subcontinental lithospheric mantle (SCLM). The basaltic magmas may have formed as a result of the infiltration of plume-derived melts into the base of the lithosphere in a continental rift setting. The Sangxiu felsic volcanic rocks share most of the geochemical features of A-type granite, and have Sr–Nd isotopic compositions which differ considerably from the Sangxiu basalts, suggesting that they originated from the anatexis of ensialic continental crust. The Sangxiu volcanic rocks may be considered as the consequence of an interaction between the Kerguelen hotspot and the lithosphere of the northeastern margin of Greater India at ～133 Ma, and may represent the initial stage of the separation of Greater India from southwestern Australia. |
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