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

作　　者：MINing WANGLiangshu LIHua XUMingjie CHENYunping LICheng ZHANGYong YUDayong 

机构地区：[1]DepartmentofEarthSciences,NanjingUniversity,Nanjing210093,China [2]SeismologicalBureauofXinjiangUygurAutonomousRegion,Urumqi830011,China

出　　处：《Chinese Science Bulletin》2005年第3期270-275,共6页

基　　金：This work was supported by the National Natural Science Foundation of China(Grant No.40072066);the Technological Innovation Foundation of Lanzhou Institute of Geology,Chinese Academy of Sciences(Grant No.03-12).

摘　　要：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 ap- pears as a velocity transitional zone except beneath two sta- tions in the northern Tarim Basin, where the Moho is char- acterized 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 moun- tain-basin-coupling system.A portable 3-component broadband digital seismic array was deployed acrossthe Tianshan orogenic belt (TOB) to investigate the lithospheric structure. Based on receiverfunction analysis of the teleseismic P-wave data, a 2 D S-wave velocity profile of the boundary areaof the TOB nd the Tarini Basin was obtained at the depths of 0-80 km. Our results reveal a verticaland lateral inhomogeneity in the crest and uppermost mantle. Four velocity interfaces divide thecrystalline crust into the upper, middle lower crust. A low velocity zone is widely observed in theupper-middle t The depth of Moho varies between 42 and 52 km. At the north end of the profile theMoho dips northward with a vertical offset of 4-6 km, which implies a subduction front f the TarimBasin into the TOB. The Moho generally ape velocity transitional zone except beneath two stations inthe northern Tarim Basin, where the Moho is characterized by a typical velocity discontinuity. Thefine velocity structure and the deep contact deformation of the crust and most mantle delineate thenorth-south lithosphere shortening and thickening in the boundary area of the TOB nd the TarimBasin, which would be helpful to constructing the geodynamical model of the intracontinentalmountain-basin-coupling system.

关 键 词：天山山脉 塔里木盆地 岩石层 造山带 地质学 

分 类 号：P54[天文地球—构造地质学] P942[天文地球—地质学]