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[1]ZHANG Bo,ZHENG Long,HE Wengui,et al.Discovery of the Dingxin Active Fault in the Western Alxa Block and Its Tectonic Significance[J].Journal of Seismological Research,2022,45(04):543-551.[doi:10.20015/j.cnki.ISSN1000-0666.2022.0054]

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Discovery of the Dingxin Active Fault in the Western Alxa Block and Its Tectonic Significance

Journal of Seismological Research[ISSN 1000-0666/CN 53-1062/P] Volume: 45 Number of periods: 2022 04 Page number: 543-551 Column: Public date: 2022-08-20

Title:: Discovery of the Dingxin Active Fault in the Western Alxa Block and Its Tectonic Significance

Author(s):: ZHANG Bo; ZHENG Long; HE Wengui; ZHU Junwen; CAI Yimeng; (Gansu Lanzhou Geophysics National Observation and Research Station,Lanzhou 730000,Gansu,China)

Keywords:: the Dingxin fault; active fault; the Alxa Block; the Tibetan Plateau

CLC:: P315.24

DOI:: 10.20015/j.cnki.ISSN1000-0666.2022.0054

Abstract:: This paper reports a newly discovered active fault,the Dingxin fault in the western part of the Alxa Block.This fault is located to the east of Dingxin Town of Jinta County,and is about 30 km long and 100°-130° in strike,and its geometric pattern slightly curves toward northest.Fifteen fault scarp profiles are measured by differential GPS,and the scarp heights ranged between(0.4±0.1)-(23.8±1.0)m,which decrease from the center of the fault to the east and the west.This indicates that the fault has long-term,dip-slip activities.Two trenches excavated at the eastern end of the fault show steep and reverse fault planes.Results from the optically stimulated luminescence(OSL)dating show that the deposition ages of the latest faulted strata are(23.38±1.99)ka and(31.25±2.66)ka respectively.This indicates that the Dingxin fault is a Late-Pleistocene fault.The discovery of the Dingxin fault,the Ebomiao fault etc.implies that the risk of large earthquakes in the Alxa Block is increasing.The distinct kinematic difference between the Dingxin fault and the Ebomiao fault reflects the complexity of inner deformation in the western Alxa Block,and its geodynamic characteristic needs to be further studied.

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Last Update: 2022-08-01