Unraveling the Dynamic Processes beneath the Northern Tibetan Plateau: Paleozoic Collision and Cenozoic Destruction of Mantle Lithosphere and Plateau Uplift
Final Report Abstract
The Tibetan Plateau is the highest and largest orogenic plateau on Earth. It has risen to an average altitude of ~5 km with little internal relief and has expanded to a width of ~2000 km since the collision of the Indian and Asian tectonic plates began at ~55 Ma. Seismic observations have been accumulating for more than half a century to constrain the mechanism of plateau uplift and extension and to reveal lithospheric deformation. However, consensus on these key issues is still lacking. As the northern Tibetan Plateau, in particular the Hoh Xil Basin (HXB), is inaccessible due to its harsh environment, most previous seismic experiments have been conducted in southern and central Tibet. During this project, we deployed two broadband seismic arrays in the eastern HXB and a dense nodal array across the Jinsha River Suture (JRS), and collected data from previous experiments in and around the area, including additional data from southern Tibet. We use these data to image the crustal and upper mantle structures beneath the Tibetan Plateau. We have applied various seismological methods, including receiver functions, surface wave tomography using earthquake waveforms and ambient noise data, body wave tomography, shear wave splitting, etc. (a) Surface wave tomography reveals widespread and correlated low-velocity anomalies in the crust and uppermost mantle beneath the HXB that cannot be explained by thermal or compositional effects and therefore require the presence of melt. Their spatial coincidence with exposed young magmatic rocks suggests that the HXB was uplifted by mantle melting and magmatic intrusion induced by lithospheric mantle removal. This further implies that subduction of the Indian plate and removal of the Tibetan mantle lithosphere control the uplift of the plateau. (b) This conclusion is confirmed by our shear-wave splitting study, which found distinct variations in the azimuthal anisotropy of the mantle across the Tibetan Plateau. (c) The joint inversion of receiver functions and dispersion curves revealed further details of the crustal and mantle melting beneath the western HXB and variations in the mantle transition zone discontinuities, which may imply material transfer at depth in the mantle transition zone. (d) The nodal array has shed more light on the detailed structure of the JRS, with extensive imbrications corresponding to a northward injection of the lower crust of the protoplateau in the late Paleogene. (e) Body wave tomography shows different structures in the lithosphere-asthenosphere system between the western and eastern HXB, suggesting different geodynamic histories of mantle-derived magmatism and differential uplift before and after the Eocene, leading to a distinct two-stage pulsating uplift model for central and northern Tibet.
Publications
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Imaging the Mantle Lithosphere below the China cratons using S-to-p converted waves. Tectonophysics, 754, 73-79.
Shen, Xuzhang; Kind, Rainer; Huang, Zhouchuan; Yuan, Xiaohui & Liu, Mian
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Seismic Evidence for Lateral Asthenospheric Flow Beneath the Northeastern Tibetan Plateau Derived From S Receiver Functions. Geochemistry, Geophysics, Geosystems, 20(2), 883-894.
Xu, Qiang; Pei, Shunping; Yuan, Xiaohui; Zhao, Junmeng; Liu, Hongbing; Tu, Hongwei & Chen, Shuze
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Complex structure of upper mantle beneath the Yadong-Gulu rift in Tibet revealed by S-to-P converted waves. Earth and Planetary Science Letters, 531, 115954.
Liu, Zhen; Tian, Xiaobo; Yuan, Xiaohui; Liang, Xiaofeng; Chen, Yun; Zhu, Gaohua; Zhang, Hongshuang; Li, Wei; Tan, Ping; Zuo, Sicheng; Wu, Chenglong; Nie, Shitan; Wang, Gaochun; Yu, Guiping & Zhou, Beibei
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Lateral growth of NE Tibetan Plateau restricted by the Asian lithosphere: Results from a dense seismic profile. Gondwana Research, 87, 238-247.
Shen, Xuzhang; Li, Yingkang; Gao, Rui; Chen, Xuanhua; Liu, Mian; Yuan, Xiaohui; Kind, Rainer; Xiong, Xiaosong; Zhang, Yipeng; Qian, Yinping; Li, Minjuan & Mei, Xiuping
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Sharp Lateral Moho Variations Across the SE Tibetan Margin and Their Implications for Plateau Growth. Journal of Geophysical Research: Solid Earth, 125(5).
Xu, Mijian; Huang, Zhouchuan; Wang, Liangshu; Xu, Mingjie; Zhang, Yueqiao; Mi, Ning; Yu, Dayong & Yuan, Xiaohui
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Eastward Dipping Style of the Underthrusting Indian Lithosphere Beneath the Tethyan Himalaya Illuminated by P and S Receiver Functions. Journal of Geophysical Research: Solid Earth, 126(1).
Xu, Qiang; Liu, Hongbing; Yuan, Xiaohui; Zhao, Junmeng & Pei, Shunping
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Intracontinental deformation of the Tianshan Orogen in response to India-Asia collision. Nature Communications, 13(1).
Li, Wei; Chen, Yun; Yuan, Xiaohui; Xiao, Wenjiao & Windley, Brian F.
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Lateral Growth Mechanism of Proto‐Tibetan Plateau in the Late Paleogene: Implications From Detailed Crustal Structures of the Hoh Xil Basin. Geophysical Research Letters, 49(9).
Wei, Yunhao; He, Rizheng; Yuan, Xiaohui; Li, Wei; Ji, Zhanbo; Niu, Xiao & Li, Zongxu
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Stepwise Lithospheric Delamination Leads to Pulsed Cenozoic Uplifts of Central Tien Shan. Lithosphere, 2022(1).
Zhao, Haixiang; Huang, Zhouchuan & Yuan, Xiaohui
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Underthrusting and Pure Shear Mechanisms Dominate the Crustal Deformation Beneath the Core of the Eastern Himalayan Syntaxis as Inferred From High‐Resolution Receiver Function Imaging. Geophysical Research Letters, 49(24).
Xu, Qiang; Ding, Lin; Pei, Shunping; Yuan, Xiaohui; Zhao, Junmeng; Liu, Hongbing; Liu, Hanlin; Li, Lei & Zuo, Hong
