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

doi:10.3969/j.issn.0253-4967.2011.02.003

Abstract

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

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

CLC Number:

P315.2

LI Tao, CHEN Jie, XIAO Wei-peng, Burbank D W, Thompson J, YANG Xiao-dong. THE DISCORVERY AND GEOLOGIC SIGNIFICANCE OF THE THRUST AT SOUTH LIMB OF THE WULAGEN ANTICLINE, SOUTH MARGIN OF THE SOUTHWESTERN TIANSHAN[J]. SEISMOLOGY AND GEOLOGY, 2011, 33(2): 277-288.

李涛, 陈杰, 肖伟鹏, Burbank D W, Thompson J, 杨晓东. 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[J]. 地震地质, 2011, 33(2): 277-288.

References

陈杰,李涛,李文巧,等.2011.帕米尔构造结及邻区的晚新生代构造与现今变形［J］.地震地质,33(2):241-259.
CHEN Jie, LI Tao, LI Wen-qiao,et al.2011. Late Cenozoic and present tectonic deformation in the Pamirs salient, northwestern China［J］. Seismology and Geology, 33(2):241-259(in Chinese).
陈杰,卢演俦,丁国瑜.2001.塔里木西缘晚新生代造山过程的记录: 磨拉石建造及生长地层和生长不整合［J］.第四纪研究,21(6): 528-539.
CHEN Jie,LU Yan-chou,DING Guo-yu.2001.Records of late Cenozoic mountain building in western Tarim Basin: Molasses,growth strata,and growth unconformity ［J］.Quaternary Sciences,21(6): 528-539(in Chinese).
陈杰,曲国胜,胡军,等.1997.帕米尔北缘弧形推覆构造带东段的基本特征与现代地震活动［J］.地震地质,19(4): 301-312.
CHEN Jie,QU Guo-sheng,HU Jun,et al.1997.Arcuate thrust tectonics and its contemporary seismicity in the eastern section of the external zone of the Pamir ［J］.Seismology and Geology,19(4): 301-312(in Chinese).
陈杰,Scharer K M,Burbank D W,等.2005.利用河流阶地限定活动褶皱的类型和生长机制: 运动学模型［J］.地震地质,27(4): 513-529.
CHEN Jie,Scharer K M,Burbank D W,et al.2005.Kinematic models of fluvial terraces over active folds: Constraints on the growth mechanism and kinematics of the fault-related folds ［J］.Seismology and Geology,27(4): 513-529(in Chinese).
陈汉林,张芬芬,程晓敢,等.2010.帕米尔东北缘地区构造变形特征与盆山构造［J］.地质科学,45(1): 102-112.
CHEN Han-lin,ZHANG Fen-fen,CHENG Xiao-gan,et al.2010.The deformation features and basin-range coupling structure in the northeastern Pamir tectonic belt ［J］.Chinese Journal of Geology,45(1): 102-112(in Chinese).
冯先岳.1994.新疆乌恰地震破裂带 .见: 国家地震局地质研究所编.活动断裂研究(3). 北京: 地震出版社.45-55.
FENG Xian-yue.1994.Surface rupture associated with the 1985 Wuqia earthquake in Xinjiang .In: Institute of Geology,SSB(ed).Research on Active Fault(3).Seismological Press,Beijing.45-55(in Chinese).
李涛,陈杰,肖伟鹏,等.2011.利用变形河流阶地限定帕米尔北缘木什背斜的缩短、隆升和侧向扩展［J］.地震地质,33(2):308-322.
LI Tao,CHEN Jie,XIAO Wei-peng,et al.2011.Using deformation terraces to confine the shortening,uplift and lateral propagation of the Mushi anticline,Northern margin of the Pamir ［J］.Seismology and Geology,33(2): 308-322(in Chinese).
潘家伟,李海兵,J Van der Woerd,等.2009.青藏高原西北部帕米尔东北缘构造地貌与活动构造研究［J］.第四纪研究,29(3): 586-598.
PAN Jia-wei,LI Hai-bing,J Van der Woerd,et al.2009.Tectonic geomorphology and active tectonics in north eastern Pamir,northwest margin of Qinghai-Tibet plateau ［J］.Quaternary Sciences,29(3): 586-598(in Chinese).
尚新璐,陈新卫,吴超,等.2004.塔里木盆地西部喀什地区的新生代冲断构造［J］.地质科学,39(4): 543-550.
SHANG Xin-lu,CHEN Xin-wei,WU Chao,et al.2004.Cenozoic thrust structures in the Kashi area,western Tarim Basin ［J］.Chinese Journal of Geology,39(4): 543-550(in Chinese).
肖安成,张春生,李景义,等.1999.干涉背斜: 冲断带内一种新的油气圈闭: 以外帕米尔阿克脱拉尔背斜为例［J］.江汉石油学报,21(2): 1-4.
XIAO An-cheng,ZHANG Chun-sheng,LI Jing-yi,et al.1999.Intersection anticline: A new petroleum trap in thrust-fold belts ［J］.Journal of Jianghan Pretraleum Institute,21(2): 1-4(in Chinese).
尹金辉,陈杰,郑勇刚,等.2001.卡兹克阿尔特断裂带活动特征［J］.中国地震,17: 221-230.
YIN Jin-hui,CHEN Jie,ZHENG Yong-gang,et al.2001.Active characteristics of Kazkeaerte Fault zone ［J］.Earthquake Research in China,17: 221-230(in Chinese).
Amos C B,Burbank D W,Nobes D C,et al.2007.Geomorphic constraints on listric thrust faulting: Implications for active deformation in the Machenzie Basin,South Island,New Zealand ［J］.Journal of Geophysical Research,112: B03S11. doi: 10.1029/2006JB004291.
Chen J,Heermance R,Burbank D W,et al.2007.Quantification of growth and lateral propagation of the Kashi anticline,southwest Chinese Tianshan ［J］.Journal of Geophysical Research,112: B03S16.doi: 10.1029/2006JB004345.
Fu B H,Ninomiya Y,Guo J.2010.Slip partitioning in the northeast Pamir-Tian Shan convergence zone ［J］.Tectonophysics,483: 344-364.
Heermance R V,Chen J,Burbank D W,et al.2008.Temporal constraints and pulsed Late Cenozoic deformation during the structural disruption of the active Kashi foreland,northwest China ［J］.Tectonics,27: TC6012.doi: 10.1029/2007TC002226.
Rockwell T K,Keller E A,Clark M N.1984.Chronology and rates of faulting of Ventura River terraces,California ［J］.Geological Society of America Bulletin,95: 1466-1474.
Rockwell T K,Keller E A,Dembrof G R.1988.Quaternary rate of folding of the Ventura Avenue anticline,western Transverse Ranges,southern California ［J］.Geological Society of America Bulletin,100: 850-858.
Scharer K M,Burbank D W,Chen J,et al.2004.Detachment folding in the southwestern Tian Shan: Tarim foreland,China: Shortening estimates and rates ［J］.Journal of Structural Geology,26: 2119-2137.doi: 10.1016/j.jsg.2004.02.016.
Scharer K M,Burbank D W,Chen J,et al.2006.Kinematic models of fluvial terraces over active detachment fold: Constraints on the growth mechanism of the Kashi-Atushi fold system,Chinese Tian Shan ［J］.Geologcial Society of America Bullutin,118: 1006-1021. doi: 10.1130/B25835.1.
Yang S F,Li J,Wang Q.2008.The deformation pattern and fault rate in the Tianshan Mountains inferred from GPS observation ［J］.Science in China Series D,51(8): 1064-1080.
Yeats R S,Clark M N,Keller E A,et al.1981.Active fault hazard in southern California: Ground rupture versus seismic shaking ［J］.Geological Society of America Bulletin,92: 189-196.
Zubovich A V,Wang X Q,Scherba Y G,et al.2010.GPS velocity field of the Tien Shan and surrouding regions ［J］.Tectonics,29: TC6014,p 23.doi: 10.1029/2010TC002772.

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