帕米尔地区现今大陆深俯冲——地震构造和动力学解释  

Recent deep subducting of continetal crust in Pamier:an interpretation on seismotectonics and geodynamics.

作　　者：张家声[1] 单新建[1] 李建华[1] 黄雄南[1] 

机构地区：[1]中国地震局地质研究所,北京100029

出　　处：《岩石学报》2005年第4期1215-1227,共13页Acta Petrologica Sinica

基　　金：国家重点基础研究发展规划项目(G1999075511;2001CB711002)资助

摘　　要：在 NEIC(UsGS)1975～1999年地震记录的基础上,补充中国新疆地震台网1975年以来的16,339个部分重新定位的有效地震记录,根据该地区地震活动时空分布规律、地壳速度结构和地表变形构造等最新研究成果,对兴都库什-帕米尔-中国西部地震活动的三维几何学及其构造联系作出了新的解释,强调沿恰曼断层的左行走滑作用对帕米尔和兴都库什地震带的制约。沿帕米尔地震带正在发生大陆深俯冲作用,是恰曼断层左行牵引的结果,深俯冲岩板为上宽下窄向恰曼断层收敛的楔形体,俯冲角度上缓(20～30°)下陡(60～70°),转变深度在80～120公里,部分下地壳物质被深俯冲作用带到200公里以下的深度。帕米尔深俯冲带上盘岩石中的多期反冲构造组合和后退俯冲作用历史,解释了该地区地壳缩短加厚和深部岩石折返的机制。与深俯冲作用相关的双地震剪切带和3个地震群的构造联系,提供了大陆深俯冲作用的动力学信息。Besides the NEIC （USGS） 1975 - 1999 seismic records, 16,339 other earthquakes occur since 1975, some of them are relocated, are added from records of Chinese Xinjiang seismic network. A 3-D geometry of the seismicity in Hindu kush-Pamir-Western China area and their structural relationship are illustrated according to the recent studies on the space-time distribution of the above earthquakes, velocity structure in the crust and surface deformation pattern in this area. An emphasize is given to the left-leteral movement along Chaman strike-slip fault which is restricting the Pamir and Hindu Kush seismic zones. The ongoing deep-subducting in the Pamir seismic zone is thought to be resulted in a traction from the left-leteral movement, where a subducting slab appears as a wedge disappearing towards to Chaman fault, and become steeper downwards from 20～30°at the upper part to 60～70°at the lower part, changing at 80～120 km. Some of lower crust material have been carried down into a depth more than 200 km. An answer about the shortening and thickening of the crust, and the returning upwards of the deep-seated rocks in the area is obtained from a facts that a multiple stage ramp thrusting and roll-back thrusting are recorded in the hanging wall of the deep-subduction zone. Tectonic relationships of the double seismic shear zones and three seismic swarms in response to the deep-subducting give new light to the dynamics about the deep-subduction of continent crust.

关 键 词：地震 地震构造 大陆深俯冲 转换断层 反冲断层作用 

分 类 号：P315.2[天文地球—地震学]