作者:
XU Xiwei (徐锡伟) WEN Xueze (闻学泽) ZHENG Rongzhang (郑荣章) MA Wentao (马文涛) SONG Fangming (宋方敏) YU Guihua (于贵华)Institute of Geology
China Seismological Bureau Beijing 100029 China Seismological Bureau of Sichuan Province Chengdu 610041 China Institute of Geology China Seismological Bureau Beijing 100029 China Institute of Geology China Seismological Bureau Beijing 100029 China Institute of Geology China Seismological Bureau Beijing 100029 China Institute of Geology China Seismological Bureau Beijing 100029 China
Based on the concept of "active blocks" and spatial distribution of historical earthquakes with surface ruptures as well as major and subordinate active faults. The Sichuan-Yunnan region can be divided into four first...
详细信息
Based on the concept of "active blocks" and spatial distribution of historical earthquakes with surface ruptures as well as major and subordinate active faults. The Sichuan-Yunnan region can be divided into four first-order blocks. They are the Markam block (I), the Sichuan-Yunnan rhombic block (II), Baoshan-Pu'er block (III), and Mizhina-Ximeng block (IV). Cut by sub-ordinate NE-trending active faults, the Sichuan-Yunnan rhombic block (II) can be further divided into two sub-blocks: the northwestern Sichuan sub-block (II1) and the middle Yunnan sub-block (II2), while the Baoshan- Pu'er block (III) can be further divided into three sub-blocks: Baoshan sub-block (III1), Jinggu sub-block (III2), and Mengla sub-block (III3). A quantitative study of offset landforms is carried out and the basic types of active faults and their long-term slip rates along the major boundaries of active blocks of different orders in the Sichuan-Yunnan region are determined, through slip vector analysis, the motion states of the active blocks are clarified and the deformation coordination on the block margins is discussed. It is suggested that the tectonic motion of the blocks in this region is a complex or superimposition of three basic types of motions: southeastward sliding, rotating on vertical axis, and uplifting. The Markam block (I), the northwestern Sichuan sub-block (II1), and middle Yunnan sub-block (II2) have a southeastward horizontal sliding rate of 1-5 mm/a, clockwise rotating angular rate of 1.4-4(/Ma, and uplifting rate of about 1 mm/a. The Baoshan-Pu'er (III) and Mizhina-Ximeng (IV) blocks have also been extensively clockwise rotated. This pattern of motion is a strain response to the collision between the Indian and Eurasian plates and the localized deformation and differential slip on the block margins associated with the northward motion of the Indian Plate. Because a set of transverse thrusts between the blocks absorbs and transforms some components of eastward or south
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