Seismic Structure Beneath the Tibetan Plateau From Iterative Finite‐Frequency Tomography Based on ChinArray: New Insights Into the Indo‐Asian Collision

Zhuo Xiao (1, 2) , Nobuaki Fuji (3, 4) , Takashi Iidaka (4) , Yuan Gao (5) , Xinlei Sun (6, 2) , Qi Liu (4)

1 Key Laboratory of Earthquake Prediction, Institute of Earthquake Forecasting, China Earthquake Administration, Beijing, China
2 Guangzhou Institute of Geochemistry, Chinese Academy of Sciences, Guangzhou, China
3 IPGP - Institut de Physique du Globe de Paris
4 Earthquake Research Institute, University of Tokyo, 1-1-1 Yayoi, Bunkyo-Ku, Tokyo 113-0032, Japan
5 Key Laboratory of Earthquake Prediction, Institute of Earthquake Forecasting, China Earthquake Administration, Beijing, China,
6 Department of Geology

Indo‐Asian continental collision has contributed to the growth of the Tibetan Plateau, which is one of the most prominent uplifts worldwide since Cenozoic. The crustal and upper‐mantle structures are key factors in understanding the evolutionary process as well as lateral growth of the plateau. We present a new 3‐D seismic model beneath the Tibetan Plateau and its surrounding areas, which uses a large‐scale dense array from iterative finite‐frequency tomography. The new tomographic images show obvious east‐west geometrical change of the northward Indian lithosphere by high‐velocity anomalies beneath Tibet. The high‐velocity anomaly extends to Pamir in the western side, but it only reaches north Lhasa in central and eastern Tibet. A convective removal of the thickened Tibetan lithosphere is observed as a high‐velocity anomaly, followed by a subvertical subduction of the Indian mantle lithosphere beneath the Bangong‐Nujiang Suture in central Tibet. We speculate its link to the widespread magmatism and rapid uplift of central Tibet in late Miocene. A high‐velocity gap between 100 and 250 km underneath the Longmenshan fault indicates that lithospheric delamination may play an important role in surface evolution between eastern Tibet and surrounding rigid blocks. Our detailed seismological model will give an insight into how the continents collide.

Domaines: Planète et Univers [physics]; Sciences de la Terre

Zhuo Xiao, Nobuaki Fuji, Takashi Iidaka, Yuan Gao, Xinlei Sun, et al.. Seismic Structure Beneath the Tibetan Plateau From Iterative Finite‐Frequency Tomography Based on ChinArray: New Insights Into the Indo‐Asian Collision. Journal of Geophysical Research : Solid Earth, 2020, 125 (2), ⟨10.1029/2019JB018344⟩. ⟨insu-02521351⟩