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

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