川滇地区现代地壳运动速度场和活动块体模型研究  

CONTEMPORARY CRUSTAL DEFORMATION AND ACTIVE TECTONIC BLOCK MODEL OF THE SICHUAN-YUNNAN REGION,CHINA

作　　者：吕江宁[1] 沈正康[2] 王敏[3] 

机构地区：[1]北京大学地球与空间科学学院地球物理系,北京100871 [2]中国地震局地质研究所,北京100029 [3]中国地震局分析预报中心,北京100036

出　　处：《地震地质》2003年第4期543-554,共12页Seismology and Geology

基　　金：国家重点基础研究发展规划项目 (G19980 4 0 70 3)资助

摘　　要：通过分析中国地壳运动观测网络的GPS数据得到川滇地区地壳水平运动速度场 ,由此划分活动块体并分析其运动特征。结果表明 :相对欧亚板块 ,滇中、雅江和中甸次级块体的顺时针转动速率分别为 0 37°± 0 16°/Ma ,0 84°± 0 39°/Ma和 0 90°± 0 39°/Ma ,造成块体间跨木里弧形断裂带约 3mm/a的SN向挤压、丽江 -大理断裂带约 4mm/a的EW向拉张和理塘断裂带约 6mm/a的近EW向拉张。鲜水河断裂带左旋走滑速率 8～ 10mm/a ,安宁河 -则木河 -小江断裂带左旋走滑 5～6mm/a。龙门山断裂带没有明显的地壳消减 ,而断裂带西北约 15 0km处有一形变速度阶跃带 ,右旋走滑速率 4～ 5mm/a。阶跃带两侧的岷山块体和阿坝地区逆时针转动速率分别为 0 13°± 0 0 8°/Ma和0 5 3°± 0 19°/Ma。鲜水河 -小江断裂带以南、以西地区 ,青藏高原物质的E向挤出和重力滑塌造成川滇块体东移 ,在东部相对稳定的华南地块的阻挡下 ,川滇块体沿鲜水河 -小江断裂带由东转向南运动 ,从而引起川滇块体内部各次级块体的顺时针转动。We derive horizontal velocity field of the Sichuan Yunnan region by analyzing GPS data collected from the Crustal Movement Observation Network of China between 1998 and 2001. Our result shows that the region is composed of 4 tectonic terrains: the Chuan Dian block, the Longmen Shan region, the Red River shear zone, and the Ruili Ximeng region. The Chuan Dian block is further decomposed into 3 sub blocks: the Dianzhong block, Yajiang block and Zhongdian block. The Longmen Shan region is decomposed into the Minshan block and the Aba region. Viewed relative to the Eurasian plate, the Dianzhong block, Yajiang block and Zhongdian block are rotating clockwise at 0.37°±0.16°/Ma, 0.84°±0.39°/Ma and 0.90°±0.39°/Ma, respectively, resulting in active faulting between the sub blocks: ～3 mm/yr north south shortening across the Muliarcuate Fault, ～4 mm/a east west extension across the Lijiang Fault, and ～6mm/a east west extension across the Litang Fault. About 8～10mm/a left lateral strike slip is detected across the Xianshuihe Fault, and 5～6mm/a left lateral strike slip across the Anninghe Zemuhe Xiaojiang Fault. No obvious crustal shortening is observed across the Longmen Shan Fault. About 150km northwest of the Longmen Shan Fault lies a velocity gradient zone with a 4～5mm/a right slip across. The Minshan block and the Aba region bounded by the gradient zone rotate counterclockwise at 0 13°±0 08°/Ma and 0 53°±0 19°/Ma relative to the Eurasian plate, respectively. Our results are consistent with a model attributing the crustal deformation of the Chuan Dian block in the Sichuan Yunnan region to be driven mainly by the eastward extrusion and gravitational collapse of the Tibetan Plateau. Being resisted by the relatively stable south China block to the east, the Chuan Dian block turns from eastward to southward motion along the Xianshuihe Xiaojiang Fault, resulting in a cluster of clockwise rotations of its internal sub blocks.

关 键 词：地壳形变 GPS 活动块体 速度场 川滇地区 

分 类 号：P228.4[天文地球—大地测量学与测量工程] P542[天文地球—测绘科学与技术]