Crustal structure beneath Tien Shan orogenic belt and its adjacent regions from multi-scale seismic data

作     者：N.Ghani KHAN BAI Ling ZHAO JunMeng LI GuoHui M.Moklesur RAHMAN CHENG Cheng YANG JianYa 

作者机构：Key Laboratory of Continental Collision and Plateau UpliftInstitute of Tibetan Plateau ResearchChinese Academy of Sciences Department of Earth SciencesCOMSATS Institute of Information Technology (CIIT) 

出 版 物：《Science China Earth Sciences》 (中国科学（地球科学英文版）)

年 卷 期：2017年第60卷第10期

页      面：1769-1782页

核心收录：

学科分类：070801[理学-固体地球物理学] 07[理学] 0708[理学-地球物理学] 

基　　金：supported by the National Natural Science Foundation of China(Grant No.41490611)to Bai L and Zhao J M the China academy of Sciences(Grant No.XDB03010702)to Zhao J M the TWAS(The world Academy of Sciences)through CAS-TWAS president fellowship to Khan N G 

主　　题：Tien Shan Earthquake relocation Velocity anomalies Differential subduction 

摘      要：As one of the world s most active intracontinental mountain belts, Tien Shan has posed questions for researchers regarding the formation of different tectonic units and active shallow seismicity. Here, we used a huge data set comprising of 7094 earthquakes from local, regional and teleseismic seismic stations. We used waveform modeling and multi-scale double-difference earthquake relocation technique to better constrain the source parameters of the earthquakes. The new set of events provided us with better initial earthquake locations for further tomographic investigation. We found that reverse-faulting earthquakes dominate the whole study area while the fault plane solutions for earthquakes beneath the northwestern Tarim Basin and the Main Pamir Thrust are diverse. There is a low-velocity anomaly beneath Bashkaingdy at depth of 80 km, and high-velocity anomalies beneath central Tien Shan at shallower depths. These observations are the keys to understand the mechanism of Tien Shan s formation because of Tarim Basin northward and Kazakh Shield s southward subduction in the south and north respectively. Velocities beneath western Tien Shan are relatively high. We thus infer that the Western Tien Shan is relatively less deformed than the eastern Tien Shan primarily due to a relatively brittle mantle.