斜切中亚的深部滑移构造带地球物理证据及对表层构造的制约

THE GEOPHYSICAL EVIDENCE OF THE LARGE-SCALENE DEEP-GLIDING TECTONIC ZONE BEVELING THE CENTRAL-ASIA AND THE RESTRICTION TO THE SURFACE STRUCTURE

斜切中亚的帕米尔—阿尔泰滑移构造带向南延伸,可与恰曼转换断裂系统相接,影响其两侧表层断裂构造格局、中新生代盆山演化、现今地壳变形和地震活动.地球卫星重力异常带在滑移构造带两侧表现出显著的不连续性和系统位移特征,其深部滑移幅度达600 km以上.从卫星资料反演计算出的地壳厚度图上可看出,新疆地区地壳厚度比中亚邻区厚4～8 km,岩石圈厚度比中亚邻区厚10～20 km.新疆及邻区地震波速层析成像结果提供了不同深度速度结构,在平行于中国西部国界处的10 km、30 km、50 km深处均有NE向速度结构不连续面的反映。

The Pamirs-Altai gliding-tectonic-zone bevels the Central-Asia and its southern extension connects to the Qia-Man transform fault system. It dominated the superficial structure framework of its both sides, the evolution of basin in the Meso-Cenozoic, the crust deformation and the earthquake activity in the nowadays. The satellite gravity anomaly zone along the two sides of gliding tectonic zone showed a notable discontinuity and some systematic shift that suggested more than 600km gliding distance in the deep. The crust thickness in Xinjiang calculated from satellite data is 4-8km that is thicker than that of adjacent area. Its lithosphere thickness calculated is 10-20kin that is thicker than in the Middle Asia. The velocity structures in different depth provided by the seismic velocity tomography data of Xinjiang and the adjacent area showed that there are velocity structure discontinuity being parallel to the west borders of China. The discontinuity belt are in NE strike and in the depth of 10km, 30kin and 50km.