Quaternary Activity of the Beihewan Fault in the Southeastern Beishan Wrench Belt, Western China: Implications for Crustal Stability and Intraplate Earthquake Hazards North of Tibet
Quaternary Activity of the Beihewan Fault in the Southeastern Beishan Wrench Belt, Western China: Implications for Crustal Stability and Intraplate Earthquake Hazards North of Tibet
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DOI：
10.1029/2018jb017209
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发表时间：
2019
期刊：
影响因子：
--
通讯作者：
Shuqing Miao（苗树青）
中科院分区：
文献类型：
--
作者：
Haibo Yang（杨海波）;Xiaoping Yang（杨晓平）;Yan Zhan（詹艳）;Dickson Cunningham;Lingqiang Zhao（照凌强）;Xiangyu Sun（孙翔宇）;Zongkai Hu（胡宗凯）;Xiongnan Huang（黄雄南）;Weiliang Huang（黄伟亮）;Shuqing Miao（苗树青）
We present evidence for the Late Quaternary activity of the Beihewan Fault (BHWF), along the.southeastern margin of the Beishan block, western China. Field observations and analysis of UAV‐derived.DEMs and Google Earth images reveal an ~10‐km‐long active fault trace in a region previously.considered tectonically inactive. Offset landforms and trench exposures reveal that the fault is dominantly.strike‐slip, with local thrust or normal displacements. Average rates of left‐lateral motion and thrusting since.the Holocene are estimated to be ~2.69 and ~0.35 mm/a, respectively. The most recent surface‐rupturing.event generated ~2.5 m of strike‐slip offset since 6.2–8.6 ka; with estimated M = 6.3–6.9. Modeling and.two‐dimensional inversion of new magnetotelluric data indicate that the BHWF is a subvertical.low‐resistivity zone that penetrates into the lower crust. Existing geological and geophysical evidence do not.support subsurface linkage between the BHWF and Altyn Tagh–Jinta‐Nanshan Fault system further south in.the Hexi Corridor. Close examination of high‐resolution satellite imagery west and east of the BHWF.reveals other Quaternary surface fault scarps, pressure ridges, offset drainages, and truncated lithological.strike belts. Collectively, these features constitute a previously unrecognized 150‐km‐long sinistral deforming.belt along the southeastern Beishan and northern Hexi Corridor boundary that we call the Southeast Beishan.Wrench Belt. Recognition of Quaternary activity along the BHWF within the larger Southeast Beishan.Wrench Belt challenges long‐held assumptions that the Beishan region is a relatively stable and tectonically.inactive block within the Late Cenozoic Indo‐Eurasian deformation field north of Tibet.
