CHANGES IN FAULT MOVEMENT PROPERTY AND GENETIC MECHANISM ON THE WESTERN SEGMENT OF THE XIANGSHAN-TIANJINGSHAN FAULT ZONE |
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| Authors: | LI Xin-nan LI Chuan-you ZHANG Pei-zhen WANG Xu-guang ZHANG Long-sheng |
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| Affiliation: | 1.State Key Laboratory of Earthquake Dynamics, Institute of Geology, China Earthquake Administration, Beijing 100029, China;2.Key Laboratory of Active Tectonics and Volcano, Institute of Geology, China Earthquake Administration, Beijing 100029, China |
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| Abstract: | The Xiangshan-Tianjingshan fault zone is an important part of the arc tectonic zone in northeastern Tibet, whose eastern segment is characterized by primarily left-lateral slip along with thrust component. In contrast, the fault movement property on the western segment of the Xiangshan-Tianjingshan fault zone is more complicated. According to the offset geomorphic features and cross sections revealed by the trenches and outcrops, the western segment is mainly a left-lateral strike-slip fault with normal component, and only accompanied with reverse component at specific positions. To determine the genetic mechanism of fault movement property on the western segment, we obtained three main factors based on the integrated analysis of fault geometry:(1)Step-overs:the left-stepping parallel faults in a sinistral shear zone create extensional step-overs and control the nearby and internal fault movement property; (2)terminal structures:they are conductive to stop rupture propagation and produce compressive deformation at the end of the fault trace; and(3)double bends:strike-slip faults have trace that bends such that slip between two adjacent blocks creates a compressive stress and thrust fault. Additionally, the Tianjingshan sub-block moves to SEE and creates an extensional stress at the end of the sub-block associated with normal faults. It shows that the Xiangshan-Tianjingshan fault zone has a complex evolution history, which is divided into two distinctive periods and characterized by laterally westward propagating. |
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| Keywords: | the western segment of the Xiangshan-Tianjingshan fault zone offset geomorphic feature fault movement property genetic mechanism |
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