地震地质 ›› 2011, Vol. 33 ›› Issue (2): 277-288.DOI: 10.3969/j.issn.0253-4967.2011.02.003

• 新构造与活动构造 • 上一篇    下一篇

西南天山前缘乌拉根背斜南翼逆断层的发现及其地质意义

李涛1, 陈杰1, 肖伟鹏1,2, Burbank D W3, Thompson J3, 杨晓东1   

  1. 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;
    2. 中国矿业大学北京地球科学与测绘工程学院, 北京 100083;
    3. Department of Earth Science,University of California,Santa Barbara, CA 93106,USA
  • 收稿日期:2011-04-07 修回日期:2011-06-18 出版日期:2011-06-29 发布日期:2011-12-17
  • 通讯作者: 陈杰,研究员,E-mail: chenjie@ies.ac.cn。
  • 作者简介:李涛,男,1985年生,2007年在吉林大学地球科学学院获学士学位,现为中国地震局地质研究所博士研究生,主要从事新构造、活动构造等方面的研究,电话: 010-62009099,E-mail: litao.410@163.com。
  • 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共同资助。

THE DISCORVERY AND GEOLOGIC SIGNIFICANCE OF THE THRUST AT SOUTH LIMB OF THE WULAGEN ANTICLINE, SOUTH MARGIN OF THE SOUTHWESTERN TIANSHAN

LI Tao1, CHEN Jie1, XIAO Wei-peng1,2, Burbank D W3, Thompson J3, YANG Xiao-dong1   

  1. 1. State Key Laboratory of Earthquake Dynamics,Institute of Geology,China Earthquake Administration, Beijing 100029,China;
    2. College of Geoscience and Surveying Engineering,China University of Mining and Technology, Beijing 100083, China;
    3. Department of Geological Sciences,University of California,Santa Barbara,CA 93106, USA
  • Received:2011-04-07 Revised:2011-06-18 Online:2011-06-29 Published:2011-12-17

摘要:

塔里木盆地新疆喀什以西部分是西南天山和帕米尔两大对冲构造系统的会聚带,关于两者变形前缘和分界的确切位置存在不同认识。在乌恰县以南的玛依卡克盆地南缘,清晰可见属于帕米尔构造带、向N或NNE逆冲的帕米尔前缘逆冲推覆体(PFT)。最近野外调查在盆地北部发现了西南天山前缘的最新变形带: 向南逆冲的乌拉根背斜南翼断层。断层总体近EW走向,在克孜勒苏河南岸和别尔托阔依河两岸河流阶地上形成了长约12km、坡向南的逆断坎,近地表断层产状为6°∠15°。 由于乌拉根背斜及其南翼断层的活动,断层上盘阶地面上形成了多条弯滑断层,并发生了明显的反向掀斜。高阶地形成以来(区域对比表明,该阶地与木什背斜北翼T2大致为同一期阶地,其光释光年龄约为16ka),西南天山南缘吸收的总缩短量约71.4km,平均缩短速率约4.5mm/a。

关键词: 天山, 帕米尔, 塔里木盆地, 乌拉根背斜南翼断层, 弯滑断层, 阶地变形

Abstract:

The western Tarim Basin is a convergent zone of the Southwestern Tianshan and the Pamir,and there have been big debates about its exact boundary.However,in the Mayikake Basin,the boundaries of two tectonic systems are very clear: the north-vergent Pamir Front Thrust is the leading edge of the Pamir,and south-vergent thrust at south limb of the Wulagen anticline,which was discovered in recent field study,is the south margin of the Southwestern Tianshan.The thrust created 7.5~17.6m high scarps on the Tk3(the high terrace of the Kezilesu river)and Tb3(the high terrace of the Bieertuokuoyi river),with an occurrence of 6°∠15°.To the west,the thrust cuts all terraces of the Bieertuokuoyi river and the underlying youngest alluvial fans ultimately.The total length of thrust trace is about 12km.As activity of the thrust,lots of subparallel flexural-slip scarps are formed on terrace surfaces,which make terrace surfaces obviously differential back-tilted(tilted to south),and the locations of tilted degrees changed are corresponding to locations of flexural-slip faults.Shortening at south limb of the Wulagen anticline is absorbed by the thrust and flexural-slip faults,which is about ~71.4m since abandonment of the high terrace.Regional correlation indicates the high terrace is the same surface as the T2 located at north limb of the Mushi anticline with the age of~16ka,which indicates the average shortening rate of south limb of the anticline in late Quaternary is~4.5mm/a.

Key words: Tianshan, Pamir, Tarim Basin, thrust at south limb of the Wulagen anticline, flexural-slip fault, terrace deformation

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