Guang-Xue REN1,chuanyou li1,Kai SUN2   

  1. 1.
    2. Institute of Geology,China Earthquake Administration
  • Received:2021-01-15 Revised:2021-06-23 Published:2021-09-26
  • Contact: chuanyou li


任光雪, 李传友,孙凯   

  1. 中国地震局地质研究所
  • 通讯作者: 李传友
  • 基金资助:

Abstract: The Karlik Tagh is located at the easternmost Tian Shan which is active due to the collision of India plate and Eurasian plate in Cenozoic and represents the geomorphological and structural end of Tian Shan. Therefore, Studying the geometry and kinematics of active faults distributed at this area has important implications for learning dynamics in Cenozoic across the joint zone. North Karlik Tagh Fault (KTNF) is an important structure at the easternmost Tian Shan, which extends about 180 km and is gently distributed between the Yiwu Basin and the north of Karlik Tagh. Based on remote sensing and detailed field research, we propose to subdivide the NKTF into 2 segments based on its variation in strike and motion characteristics. At the west of the NKTF, the west segment is mainly present south of Yanchi county and and extends about 61 km. The fault trace along Yanchi segment is obvious presenting several liner faults scarps on foreland alluvial fan surfaces. Outcrop shows that this fault dips SW and directly NE thrusts. Topographic profiles across scraps have shown a vertical offset of 1.3±0.5 m~7.3±0.3 m. Based on the OSL dating of deformed T1 terrace and the vertical displacement of 1.3 ±0.5 m, a vertical slip rate of 0.19 mm/a can be obtained. This vertical rate is slightly large than that of the North Hami Basin Fault, which is consistent with the S-directed title of the Karlik Tagh. At south of Xiamaya town, the NKTF changes its strike and bends to NE for 95 km. Toward the east, this fault segment can be connected with the west end of Gobi-Tianshan fault system (GTSFS). There are clear evidences of recent activity, including well-preserved scarps and offset streams on the alluvial sediments. About 23 km southeast of Xiamaya town, the fault trace runs across a north-flowing river, causing dextral offset of the T3/T2 terrace ridge with the maximum displacement of 172±20 m. About 10 km northeast of this river, a massif with steep slope on the south and gentle slope on the north is passed through by the NKTF. Field observation of outcrop has shown that this fault trends NE 156°and displays revers faulting component. The NKTF, HMNF and adjacent NW thrust faults can act as the horse splay of west end of the Gobi-Tianshan fault system and displays a positive flower structure in cross-section. The uplift of Karlik Tagh is controlled by NW thrust fault and NEE left-lateral strike-slip fault, and this range is a typical of transpressional mountain in the easternmost Tian Shan.

Key words: North Karlik Tagh Fault, Movement feature, Transpressional deformation, Easternmost Tian Shan

摘要: 喀尔里克山位于天山最东端,是天山造山带往东地貌和构造的终止区,研究该地区断裂结构和运动学特征对全面认识天山新生代变形模式具有重要意义。喀尔里克山北缘断裂呈弧形展布在喀尔里克山北侧,向东延伸与戈壁-天山左旋走滑断裂系相连。根据其走向和运动特征的差异可将喀尔里克山北缘断裂分为东西两段。西段长约61 km,走向NW,逆冲性质,断裂活动在山前洪积扇上形成了多条断层陡坎。利用光释光对变形阶地进行定年得到西段全新世垂直滑动速率为0.19mm/a~ 0.35 mm/a,该滑动速率略大于喀尔里克山南侧的哈密盆地北缘断裂的垂直滑动速率,这与山体向南掀斜的地貌特征一致。东段长约95 km,NE走向,运动以左旋走滑为主,剖面显示该断裂段还具有一定逆冲分量,断裂左旋错断了一系列冲沟和河流阶地。喀尔里克山北缘断裂、伊吾周缘NW向逆冲断裂与哈密盆地北缘断裂共同构成了戈壁-天山左旋走滑断裂系的马尾状端部结构,这些断裂在深部收敛汇聚在剖面上形成一个不对称的正花状构造。喀尔里克山体的抬升受两侧逆冲断裂和东侧左旋走滑断裂共同控制,表现为转换挤压变形抬升的特征,山体通过南北山前逆冲断裂向盆地一侧的迁移逐渐向外扩展。

关键词: 喀尔里克山北缘断裂 运动特征 转换挤压变形 天山东端