地震地质 ›› 2011, Vol. 33 ›› Issue (2): 241-259.DOI: 10.3969/j.issn.0253-4967.2011.02.001

• 新构造与活动构造 • 上一篇    下一篇

帕米尔构造结及邻区的晚新生代构造与现今变形

陈杰, 李涛, 李文巧, 袁兆德   

  1. 中国地震局地质研究所, 地震动力学国家重点实验室, 北京 100029
  • 收稿日期:2011-06-20 修回日期:2011-06-25 出版日期:2011-06-29 发布日期:2011-12-17
  • 作者简介:陈杰,男,1966年生,1995年于国家地震局地质研究所获构造地质学专业博士学位,研究员,现主要从事新构造、活动构造与年代学研究,电话010-62009093,E-mail: chenjie@ies.ac.cn。
  • 基金资助:

    科技部国际科技合作计划项目(2008DFA20860)、地震动力学国家重点实验室自主研究课题(LED2010A04)和我国地震重点监视防御区活动断层地震危险性评价项目资助。

LATE CENOZOIC AND PRESENT TECTONIC DEFORMATION IN THE PAMIR SALIENT,NORTHWESTERN CHINA

CHEN Jie, LI Tao, LI Wen-qiao, YUAN Zhao-de   

  1. State Key Laboratory of Earthquake Dynamics, Institute of Geology, China Earthquake Administration, Beijing 100029, China
  • Received:2011-06-20 Revised:2011-06-25 Online:2011-06-29 Published:2011-12-17

摘要:

帕米尔构造结是中国大陆受板块动力作用和地震活动最强烈的地区之一。晚新生代帕米尔构造结北部向北楔入推移了约300km,但对这一变形过程至今未能很好的限定。帕米尔构造结的晚新生代构造变形在空间上是不对称的。帕米尔西缘表现为NW向的径向逆冲,伴随着塔吉克盆地东部块体绕垂直轴的逆时针旋转。在帕米尔东部,构造变形的方式、空间分布和机制是随时间变化的。在渐新世末至约11Ma,帕米尔东部以喀什-叶城转换带(KYTS)的右旋走滑作用为主,同时帕米尔前缘沿主帕米尔逆断层(MPT)发生强烈缩短作用,塔里木向南俯冲,帕米尔中、下地壳相对于上地壳向北俯冲并加厚、熔融。弧形弯曲或径向逆冲作用以及中、下地壳的加厚、弱化致使公格尔山拉张系北部于7~8Ma开始EW向拉张作用,并向南扩展。至3~5Ma,构造格局发生了巨变,喀喇昆仑右旋走滑断裂北段停止活动; KYTS右旋走滑由早期的11~15mm/a明显减小至1.7~5.3mm/a; 帕米尔构造结与塔里木块体间的相对运动明显减弱,两者可能已拼接在一起作为一个整体以(21±1)mm/a的速率向北推挤,变形前锋向北迁移至克孜勒苏河一线。帕米尔构造结及邻区晚第四纪及现今的活动变形主要集中在公格尔拉张系、帕米尔前缘褶皱-逆断层带(PFT)与南天山南缘的阿图什-喀什褶皱带上。

关键词: 帕米尔构造结, 晚新生代构造, 拉张作用, 径向逆冲, 弧形弯曲

Abstract:

The northern margin of the Pamir salient indented northward by ~300km during the late Cenozoic,however,the spatiotemporal evolution of this process is still poorly constrained.Regional deformation within the Pamir salient is asymmetric.Previous work has shown that deformation along the western flank of the Pamir was accommodated by northwest-directed radial thrusting and associated anticlockwise vertical axis rotation of the Pamir over the eastern margin of the Tajik Basin,along with a component of left-slip faulting along the Darvaz Fault.In contrast,subduction of the Tajik-Tarim Basin beneath the Pamir along the MPT was absorbed along the eastern margin of the salient by dextral-slip along the Kashgar-Yecheng transfer system,accompanied with Oligocene-Miocene northward underthrusting, thickening and widespread melting of the middle and lower crust beneath the Pamir,eventually led to east-west extension along the Kongur Shan extensional system at ~7~8Ma.The slip rate of the KYTS decreased substantially from 11~15mm/a to 1.7~5.3mm/a since at least 3~5Ma,termination of slip along the northern segment of the Karakorum Fault occurred almost at the same time.Late Quaternary and present active deformation in the Pamir is dominated by east-west extension along the Kongur Shan extensional system and north-south contraction along the PFT and the Atux-Kashi fold belts in the southern margin of Tianshan.

Key words: Pamir salient, late Cenozoic deformation, east-west extension, radial thrusting, oroclinal bending

中图分类号: