Cenozoic volcanism and tectonic evolution of the Tibetan plateau |
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| Authors: | Linqi Xia Xiangmin Li Zhongping Ma Xueyi Xu Zuchun Xia |
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| Institution: | 1. Chengdu Institute of Geology and Mineral Resources, Chengdu 610081, China;2. State Key Laboratory of Isotope Geochemistry, Guangzhou Institute of Geochemistry, Chinese Academy of Sciences, Guangzhou 510640, China;1. Key Laboratory of Cenozoic Geology and Environment, Institute of Geology and Geophysics, Chinese Academy of Sciences, P.O. Box 9825, Beijing 100029, China;2. School of Earth and Environment, University of Leeds, Leeds LS2 9JT, UK;1. State Key Laboratory of Continental Dynamics, Department of Geology, Northwest University, Xi''an 710069, China;2. Geologie, Technische Universität Bergakademie Freiberg, 09599 Freiberg, Germany;3. Institute of Geology, University of Azad Jammu and Kashmir Muzaffarabad, AJK 13100, Pakistan;1. Institute of Geology, Chinese Academy of Geological Sciences, Beijing 100037, China;2. China University of Geosciences, Beijing 100083, China;3. State Key Laboratory of Continental Dynamics, Department of Geology, Northwest University, Xi''an 710069, China;4. Institute of Mineral Resources, Chinese Academy of Geological Sciences, Beijing 100037, China |
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| Abstract: | Cenozoic volcanism on the Tibetan plateau, which shows systematic variations in space and time, is the volcanic response to the India–Asia continental collision. The volcanism gradually changed from Na-rich + K-rich to potassic–ultrapotassic + adakitic compositions along with the India–Asia collision shifting from contact-collision (i.e. “soft collision” or “syn-collision”) to all-sided collision (i.e. “hard collision”). The sodium-rich and potasium-rich lavas with ages of 65–40 Ma distribute mainly in the Lhasa terrane of southern Tibet and subordinately in the Qiangtang terrane of central Tibet. The widespread potassic–ultrapotassic lavas and subordinate adakites were generated from ~ 45 to 26 Ma in the Qiangtang terrane of central Tibet. Subsequent post-collisional volcanism migrated southwards, producing ultrapotassic and adakitic lavas coevally between ~ 26 and 8 Ma in the Lhasa terrane. Then potassic and minor adakitic volcanism was renewed to the north and has become extensive and semicontinuous since ~ 20 Ma in the western Qiangtang and Songpan–Ganze terranes. Such spatial–temporal variations provide important constraints on the geodynamic processes that evolved at depth to form the Tibetan plateau. These processes involve roll-back and break-off of the subducted Neo-Tethyan slab followed by removal of the thickened Lhasa lithospheric root, and consequently northward underthrusting of the Indian lithosphere. The Tibetan plateau is suggested to have risen diachronously from south to north. Whereas the southern part of the plateau may have been created and maintained since the late-Oligocene, the northern plateau would have not attained its present-day elevation and size until the mid-Miocene when the lower part of the western Qiangtang and Songpan–Ganze lithospheres began to founder and detach owing to the persistently northward push of the underthrust Indian lithosphere. |
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