TY - JOUR
T1 - Episodic Lithospheric Deformation in Eastern Tibet Inferred From Seismic Anisotropy
AU - Bao, Xuewei
AU - Song, Xiaodong
AU - Eaton, David W.
AU - Xu, Yixian
AU - Chen, Hanlin
N1 - Funding Information:
We thank the Editor (Dr. Jeroen Ritsema) and two anonymous reviewers for their constructive comments, which have greatly improved the manuscript. This research was supported by the Natural Science Foundation of China (41774045 and 41830212) and the Fundamental Research Funds for the Central Universities. The seismic waveform data were obtained from the Data Management Centre of China National Seismic Network at Institute of Geophysics, China Earthquake Administration (doi:10.11998/SeisDmc/SN, http://www.seisdmc.ac.cn), which is only accessible in China due to proprietary concerns, and the Data Management Center at the Incorporated Research Institution of Seismology (http://www.iris.edu/hq/). Most figures were prepared using Generic Mapping Tools (GMT) (Wessel & Smith,). Our azimuthally anisotropic Vsv model is available from the supporting information.
Publisher Copyright:
©2020. American Geophysical Union. All Rights Reserved.
PY - 2020/2/16
Y1 - 2020/2/16
N2 - Mechanisms for uplift and deformation of the Tibetan Plateau remain vigorously debated; hypotheses include stepwise growth, distributed thickening, and crustal channel flow, each with a distinct anisotropic signature. We have developed a new azimuthally anisotropic shear velocity model for the lithosphere beneath eastern Tibet, based on ambient noise tomography from 643 seismic stations. In our model, the Tibetan upper crust is characterized by strong anisotropy with fast axes that correlate with surface geology and mantle anisotropy, suggesting the occurrence of coherent deformation. However, a much different picture emerges in the middle and lower crust, where anisotropy is disordered and weaker beneath the plateau than along its margins, inconsistent with the prediction of large-scale eastward crust flow in eastern Tibet. Our observations are best explained by heterogeneous crustal thickening beneath the plateau with complex flow in the middle and lower crust, accompanied by asthenospheric upwelling along the southeastern plateau margin.
AB - Mechanisms for uplift and deformation of the Tibetan Plateau remain vigorously debated; hypotheses include stepwise growth, distributed thickening, and crustal channel flow, each with a distinct anisotropic signature. We have developed a new azimuthally anisotropic shear velocity model for the lithosphere beneath eastern Tibet, based on ambient noise tomography from 643 seismic stations. In our model, the Tibetan upper crust is characterized by strong anisotropy with fast axes that correlate with surface geology and mantle anisotropy, suggesting the occurrence of coherent deformation. However, a much different picture emerges in the middle and lower crust, where anisotropy is disordered and weaker beneath the plateau than along its margins, inconsistent with the prediction of large-scale eastward crust flow in eastern Tibet. Our observations are best explained by heterogeneous crustal thickening beneath the plateau with complex flow in the middle and lower crust, accompanied by asthenospheric upwelling along the southeastern plateau margin.
KW - ambient noise tomography
KW - azimuthal anisotropy
KW - lithospheric deformation
KW - the Tibetan Plateau
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U2 - 10.1029/2019GL085721
DO - 10.1029/2019GL085721
M3 - Article
AN - SCOPUS:85079575586
VL - 47
JO - Geophysical Research Letters
JF - Geophysical Research Letters
SN - 0094-8276
IS - 3
M1 - e2019GL085721
ER -