天山北麓库松木契克山山前断裂东段断层陡坎研究  

A STUDY ON THE SCARPS ALONG THE EASTERN SECTION OF THE KUSONGMUQIKE PIEDMONT FAULT AT THE NORTHERN FOOT OF TIANSHAN

作　　者：黄帅堂 常想德[1] 马建 胡伟华[1] 任静[2] 刘建明[1] 张文秀[1] 赖爱京[3] HUANG Shuai-tang;CHANG Xiang-de;MA Jian;HU Wei-hua;REN Jing;LIU Jian-ming;ZHANG Wen-xiu;LAI Ai-jing(Earthquake Agency of Xinjiang Uygur Autonomous Region,Urumqi 830011,China;China Earthquake Networks Center,Beijing 100045,China;Akesu Earthquake Monitoring Center Station,Akesu 843000,Xinjiang,China)

机构地区：[1]新疆维吾尔自治区地震局,乌鲁木齐830011 [2]中国地震台网中心,北京100045 [3]新疆维吾尔自治区地震局,阿克苏地震监测中心站,阿克苏843000

出　　处：《地震地质》2022年第1期20-34,共15页Seismology and Geology

基　　金：中国地震局地震工程与工程振动重点实验室重点专项(2020EEEVL0203);新疆地震灾害风险评估创新团队(XJDZCXTD2020-2);中国地震局地质研究所所长基金(JB-19-06);中国地震局地质研究所援疆项目(IGCEA2009);新疆地震局基金(201910)共同资助。

摘　　要：北天山逆断裂-褶皱带位于天山北麓与准噶尔盆地的交界处,其中库松木契克山山前断裂位于精河县城南部,是北天山西部山前一条重要的逆冲活动断裂带。断裂带东段附近近十年来至少发生过3次5.0级以上地震,详细研究其几何展布、构造地貌特征有助于理解天山地区晚第四纪以来的构造变形特征以及区域应变分配模式。文中利用高分辨遥感Google Earth影像解译、无人机航测和差分GPS地形剖面测量,并结合野外地质调查等手段进行了探察。所得结果显示,库松木契克山山前断裂东段由南、北2支次级逆断裂构成。其中,南支新龙口断层由5条雁列展布的次级断层组成,总体走向NW,倾向S,倾角陡立,全长约48km,断层断错山前2期冲洪积扇和5级河流阶地,T1、T2阶地和fan3的活动时代最新,断层陡坎高3.6~4.7m,为断层同期活动的产物,T3和T4阶地垂直位移量分别为13.5m和20.3m,T5阶地的垂直位移与阶地周边fan2洪积扇基本一致,约为30m。冲洪积扇fan1上断层通过的部位无构造变形,地表保留了原始地貌形态;北支水文站断层断续分布,总体走向近EW,全长约44km,断错多期冲洪积扇,在fan3冲洪积扇北缘发育2条近平行的正向陡坎,其他断层则切穿洪积扇及表面的冲沟,在地表形成陡立的反向陡坎。顺坡向陡坎高度累加的最大垂直位移量达17.2m,最小垂直位移量为0.3m,陡坎高度主要集中于4.7~9.9m。反向断层陡坎的最大垂直位移量为7.8~9.8m,最小陡坎高度为2.4~3.1m,陡坎高度主要集中于3.3~9.2m,在2组断层之间零星发育多条次级断层,陡坎高0.5~1.0m不等。就陡坎高度分布而言,其垂直位移有自西向东逐渐降低的分布规律。这些结果有助于进一步理解北天山西部地区的应变分配模式。Thrust fault is the basic model of crustal deformation and also one of the major structural forms of orogenic belts,indicating the tectonic environment of compression.Most of the catastrophic earthquakes that affect human activity occur within the plates.In the interior of the plate,reverse faults are likely to develop as long as there is compressive stress in the regional sense or under some local tectonic conditions.It is considered that the NS compression resulting from collision of the Indian plate and the Eurasian plate is the main cause for the formation of the present tectonic framework in both north and south sides of Tianshan Mountains.The continuous crustal shortening and thickening has made the Quaternary active structures in the front margins of Tianshan Mountains well developed.Meanwhile,the new nappe structures in front of Tianshan Mountains are also the main sites for the preparation of medium-strong earthquakes in the Tianshan Mountains area,and their seismogenic mode is mostly in the forms of blind fault ramp-decollement plane-surface fault ramps.The northern Tianshan inverse fault-fold belt is located at the junction between the northern foothill of Tianshan Mountains and Junggar Basin,where the Kusongmuqike piedmont fault is located in the south of Jinghe County,and is an important active thrust fault belt in the western northern Tianshan Mountains.In recent ten years,there were many earthquakes with magnitude 5.0 or above occurring in the eastern section of the fault zone.A detailed study of the geometric distribution and tectonic geomorphologic features is helpful to understand the tectonic deformation characteristics and regional strain distribution in the Tianshan area since the late Quaternary.The results of high-resolution remote sensing image interpretation,UAV aerial survey and differential GPS terrain profile survey combined with field geological survey show that the eastern segment of the Kusongmuqike piedmont fault is composed of two secondary reverse faults.Among them,the south bran

关 键 词：天山北麓 库松木契克山山前断裂 几何结构 断层陡坎 垂直位错 

分 类 号：P315.2[天文地球—地震学]