地震地质 ›› 2003, Vol. 25 ›› Issue (1): 61-70.

• 研究论文 • 上一篇    下一篇

川滇菱形块体顺时针转动的构造学与古地磁学证据

徐锡伟1, 程国良1, 于贵华1, 宋方敏1, 向宏发1, 张兰凤1, Hagai Ron2, 王洋龙3, 闻学泽4   

  1. 1. 中国地震局地质研究所, 北京, 100029;
    2. 以色列地球物理研究所, P.O.Box, 182;
    3. 云南省地震局, 昆明, 650204;
    4. 四川省地震局, 成都, 610041
  • 收稿日期:2001-08-13 修回日期:2002-04-22 出版日期:2003-03-06 发布日期:2009-10-26
  • 作者简介:徐锡伟,男,1962年生,1989年在国家地震局地质研究所(中国科技大学研究生院)获得博士学位,研究员,中国地震局活动构造探测研究中心主任,活动构造室主任,主要从事构造地质学、活动构造学和地震灾害等研究,电话:010-62009025,E-mail:xiweixu@vip.sin.com或xxiwei@public3.bta.net.cn.
  • 基金资助:
    国家重点基础研究发展规划项目(G1998040701)资助.中国地震局地质研究所论著2003B0003.

TECTONIC AND PALEOMAGNETIC EVIDENCE FOR THE CLOCKWISE ROTATION OF THE SICHUAN- YUNNAN RHOMBIC BLOCK

XU Xi-wei1, CHENG Guo-liang1, YU Gui-hua1, SONG Fang-min1, XIANG Hong-fa1, ZHANG Lan-feng1, Hagai Ron2, WANG Yang-long3, WEN Xue-ze4   

  1. 1. Institute of Geology, China Seismological Bureau, Beijing 100029, China;
    2. Institute of Geophysics, Israel, P. O. Box 182;
    3. Seismological Bureau of Yunnan Province, Kunming 650204, China;
    4. Seismological Bureau of Sichuan Province, Chengdu 610041, China
  • Received:2001-08-13 Revised:2002-04-22 Online:2003-03-06 Published:2009-10-26

摘要: 川滇菱形块体内部受NE向丽江-小金河断裂的切割,可进一步划分为川西北次级块体和滇中次级块体等南北2个部分;各次级块体东边界断裂有规律地左旋滑动、西边界断裂的右旋滑动及其滑动速率值的差异,反映出新生代时期各次级块体作向SE的水平滑移叠加绕垂直轴顺时针转动的复合运动.其中,川西北次级块体SE向的水平滑移速率5mm/a,顺时针转动角速度1.4°/Ma;滇中次级块体SE向的水平滑移速率3.5mm/a,顺时针转动角速度约1.5°/Ma.在滇中次级块体内部姚安、大姚、永仁、昆明北马街等地采集到约90个古新世地层的定向样品,通过交变退磁和热退磁获得了它们各自的剩磁矢量(实验磁偏角和磁倾角),由实测磁偏角与期望磁偏角相比可知川滇地区滇中次级块体中新世早期以来的顺时针转动累积量可达30°~48°.次级块体的整体转动与块边活动断裂的左旋滑动符合左旋走滑断裂作用区块体作顺时针转动的运动学模式.

关键词: 活动断裂, 活动块体, 块体转动, 磁偏角期望值, 磁偏角实测值, 川滇地区

Abstract: The inner part of the Sichuan-Yunnan rhombic block is dissected by the Lijiang-Xiaojinhe Fault, and hence can be subdivided into Northwest Sichuan sub-block in the north and Central Yunnan sub-block in the south. The eastern boundary faults of these two sub-blocks are regularly characterized by left-lateral strike-slip, while the western boundary faults are characterized by right-lateral strike-slip. The slip rate of both the eastern and western boundary faults are significantly different. All these phenomena may indicate the composite movement of these sub-blocks characterized by southeastward horizontal slipping associated with clockwise rotation around a vertical axis during the Cenozoic time. Among them, the horizontal slip rate of the Southwest Sichuan sub-block is 5mm/a, and the angular velocity of clockwise rotation is about 1 4°/Ma, while those of the Central Yunnan sub-block are 3.5mm/a and 1 5°/Ma, respectively. About 90 oriented samples have been collected from Paleogene strata in Yaoan, Dayao, Yongren and Beimajie of Kunming within the Central Yunnan sub-block. The vectors of remanent magnetism of each sample (measured magnetic declination and inclination) have been obtained through alternating field demagnetization and thermal demagnetization. The comparison between the measured magnetic declination and the expected value shows that the accumulated clockwise rotation of the Central Yunnan sub-block of the Sichuan-Yunnan rhombic block since early Miocene has reached up to 30°~48°. The feature represented by the entire rotation of the sub-blocks accompanied by left-lateral slipping along the boundary active faults is consistent with the kinetic model of clockwise rotation of the block in left-lateral strike-slip faulting region.

Key words: active fault, active block, block rotation, expected magnetic declination, measured magnetic declination, Sichuan-Yunnan region

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