Velocity structure of the crust and uppermost mantle in the boundary area of the Tianshan Mountains and the Tarim Basin

A portable 3-component broadband digital seismic array was deployed across the Tianshan orogenic belt (TOB) to investigate the lithospheric structure. Based on receiver function analysis of the teleseismic P-wave data, a 2-D S-wave velocity profile of the boundary area of the TOB and the Tarim Basin was obtained at the depths of 0-80 km. Our results reveal a vertical and lateral inhomogeneity in the crust and uppermost mantle. Four velocity interfaces divide the crystalline crust into the upper, middle and lower crust. A low velocity zone is widely observed in the upper-middle crust. The depth of Moho varies between 42 and 52 km. At the north end of the profile the Moho dips northward with a vertical offset of 4-6 km, which implies a subduction front of the Tarim Basin into the TOB. The Moho generally appears as a velocity transitional zone except beneath two stations in the northern Tarim Basin, where the Moho is characterized by a typical velocity discontinuity. The fine velocity structure and the deep contact deformation of the crust and upper most mantle delineate the north-south lithospheric shortening and thickening in the boundary area of the TOB and the Tarim Basin, which would be helpful to constructing the geodynamical model of the intracontinental mountain-basin-coupling system.

作 者： MI Ning WANG Liangshu LI Hua Xu Mingjie Chen Yunping LI Cheng ZHANG Yong YU Dayong   作者單位： MI Ning,WANG Liangshu,LI Hua,Xu Mingjie,Chen Yunping,LI Cheng,YU Dayong(Department of Earth Sciences, Nanjing University, Nanjing 210093, China)

ZHANG Yong(Seismological Bureau of Xinjiang Uygur Autonomous Region, Urumqi 830011, China) 

刊 名： 科學通報（英文版）  SCI 英文刊名： CHINESE SCIENCE BULLETIN  年，卷(期)： 2005 50(3)  分類號： P5  關鍵詞： Tianshan orogenic belt   receiver function   low velocity zone   mountain-basin-coupling system  

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