【摘要】 利用流动地震台阵记录的地震数据,通过地震层析技术反演了天山—帕米尔结合带的P波速度结构,揭示出地壳结构的非均匀特征及其与地震活动的对应关系.分析结果表明,天山和西昆仑的双向挤压导致塔里木西部边缘地壳严重变形,在山前地区形成基底隆起带,地壳深部则被断裂分割成为若干块体,有的块体可能卷入造山带内部;喀什坳陷地壳深部结构相对完整,变形程度较弱;天山和西昆仑的地壳结构显示出缩短增厚的波速特性,在与塔里木接壤的局部地区,壳幔边界附近存在热物质的侵入迹象.大部分地震都发生在塔里木西部边缘的壳内高速块体周围,推测块体之间的相互作用和应力调整是导致天山—帕米尔结合带频繁发生地震的主要原因,伽师地震则与构造变形由天山向塔里木内部扩展以及该地区的地壳非均匀结构有关.更多还原

【Abstract】 Using recording data from a temporary seismic network, we obtained P wave velocity structure of the Tianshan-Pamir conjunctive zone by tomographic inversion, revealing the heterogeneity of crustal structure and its relations to seismic activity. The results show that the collision between the Tianshan and Pamir caused strong crustal deformation on the western edge of the Tarim basin and resulted in basement uplift zones in the foreland areas. The deep crust is separated into several blocks by faults and some of them are wrapped within mountain belts. The deep crust of the Kashi depression has a relatively stable structure with less deformation, while the crust of the Tianshan and western Kunlun shows a velocity feature of shortening and thickening. Moreover, evidence of heating or hot perturbation can be observed near the crust-mantle boundary beneath the areas adjacent to the Tarim basin. Most earthquakes in this area are concentrated around high velocity blocks in the western end of the Tarim basin. We infer that the frequent earthquakes in the Tianshan-Pamir conjunctive zone can be attributed to the interaction and stress adjustment between these blocks, while the earthquakes in the Jiashi area is related to the penetration of tectonic activity from the Tianshan into the Tarim basin and the heterogeneous structure of the crust.更多还原