新疆伽师强震群区基底界面结构特征  

BASEMENT INTERFACE STRUCTURAL CHARACTERISTICS BENEATH JIASHI STRONG EARTHQUAKE SWARM AREA IN XINJIANG,CHINA

作　　者：徐朝繁[1] 段永红[1] 田晓峰[1] 潘纪顺[1] 张建狮[1] 胡修奇 

机构地区：[1]中国地震局地球物理勘探中心,中国郑州450002 [2]河南省地震局,中国郑州450000

出　　处：《地震学报》2007年第5期477-482,共6页Acta Seismologica Sinica

基　　金：地震科学联合基金(106076);国家自然科学基金(40474049;40334040)资助

摘　　要：用射线分布分析法对伽师强震群区的高分辨折射地震剖面资料进行了更进一步的分析处理,得到了伽师强震群区更完整的基底界面结构特征.结果表明,在伽师强震群区地壳上部存在两个明显的结构界面:第一个界面的结构连续、完整,其埋深变化不大,在2.6～3.3km之间,为一向天山方向逐渐抬升、近平直的倾斜界面;第二个界面的埋深变化较大,在8.5～11.8km之间,为古老的塔里木盆地结晶基底.在约37km桩号附近结晶基底有近2.5km的深度突变,推断可能是伽师强震群区超基底断裂所致.以该断裂为界,结晶基底分为西南、东北两段.每段内界面的埋深变化不大,西南段的埋深约11.5km,东北段的埋深约为8.5～9.0km,该段在从西南向东北整体抬升的背景上略有上隆,反映出在塔里木地块西北缘特殊的构造环境下上部地壳的变形特征.The seismic data obtained from high resolution seismic refraction profile in Jiashi strong earthquake swarm area in Xinjiang China were further processed with ray hit analysis method and more complete basement interface structural characteristics beneath Jiashi strong earthquake swarm area were determined. The results show that there are two clear basement interfaces at the upper crust in Jiashi strong earthquake swarm area. The first one with buried depth ranging from 2.6 km to 3.3 km presents integral and continuous structure, and it appears an inclined plane interface and smoothly rises up toward Tianshan mountain. The second basement interface with buried depth from 8.5 km to 11.8 km, is the antiquated crystalline basement of Tarim basin. Near the post number of 37 km, the buried depth of the crystalline basement changed abruptly by 2.5 km, which maybe result from an ultra crystalline basement fault. If taking this fault as a boundary, the crystalline basement could be divided into two parts, i.e. the southwestern segment with buried depth about 11.5 km, and the northeastern segment with buried depth approximately from 8.5 km to 9.0 km. That is to say, in each segment, the buried depth changes not too much. The northeast segment rises up as a whole and upheaves slightly from southwest to northeast, which reflects the upper crustal deformation characteristics under the special tectonic background at the northwestern edge of Tarim basin.

关 键 词：伽师强震群区 高分辨折射探测 射线分布分析 基底界面结构 超基底断裂 

分 类 号：P313.2[天文地球—固体地球物理学]