Abstract

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Title:: Kinematics Characteristics of Heishan Fault in the Western Hexi Corridor and Its Implications for Regional Tectonic Transformation

Author(s):: ZHANG Ning; ZHENG Wen-jun; LIU Xing-wang; WANG Wei-tao; LI Xin-nan; HE Wen-gui; LEI Qi-yun; SHAO Yan-xiu; 1. State Key Laboratory of Earthquake Dynamics, Institute of Geology, China Earthquake Administration, Beijing 100029, China; 2. Lanzhou Institute of Seismology, China Earthquake Administration, Lanzhou 730000, Gansu, China; 3. Key Laboratory of Western China’s Environmental Systems of Ministry of Education, Lanzhou University, Lanzhou 730000, Gansu, China; 4. Earthquake Administration of Ningxia Hui Autonomous Region, Yinchuan 750001, Ningxia, China

Keywords:: active tectonic; Heishan fault; offset geomorphology; thrust slip rate; tectonic transformation; deformational geometry; Jiuxi Basin; Altyn Tagh fault

Abstract:: Located in the northern of the western Hexi Corridor, Heishan fault is the northern boundary of Jiuxi Basin and an important fault at the eastern end of Altyn Tagh fault. The vertical components of slip rates of (0.26±0.06)mm per year for Heishan fault by topographic profiling and dating age for alluvial fan were determined. Heishan fault is a high-angle reverse fault, which is different from the sense of motion of Altyn Tagh fault. Combined with the previous studies on the NW-striking faults in Jiuxi Basin, the total shortening rate of 1.4-2.4 mm per year along the direction parallel to Altyn Tagh fault in the western Hexi Corridor was constrainted, consistenting with the strike-slip rates of 1-2 mm per year at the eastern end of Altyn Tagh fault. Thus, it is inferred that the left-lateral strike slip at the eastern end of Altyn Tagh fault has been absorbed by the reverse faulting and folding of Quaternary crust in the western Hexi Corridor. The left-lateral strike-slip rates in Altyn Tagh fault decrease along the northeastern direction and the fault terminated near Kuantanshan in the western Hexi Corridor. Heishan fault, Dengdengshan fault and Jintananshan fault maybe comprise the most northeastern frontier of Qinghai-Tibet Plateau.