青藏高原东北缘榆木山东缘断裂地表破裂带的新发现及其地震地质意义  

THE NEW FINDINGS OF SURFACE RUPTURE ZONES AND ITS SEISMOLOGICAL SIGNIFICANCE OF THE EASTERN MARGIN OF YUMUSHAN FAULT,NORTHEASTERN MARGIN OF QINGZANG PLATEAU

作　　者：陈柏旭 余中元 肖鹏 戴训也 张世龙 郑荣荧 CHEN Bai-xu;YU Zhong-yuan;XIAO Peng;DAI Xun-ye;ZHANG Shi-long;ZHENG Rong-ying(Institute of Disaster Prevention,Langfang,Sanhe 605201,China;Beijing Disaster Prevention Technology Co.,Ltd.,Beijing 101100,China;Hebei Key Laboratory of Earthquake Dynamics,Sanhe 065201,China)

机构地区：[1]防灾科技学院,三河065201 [2]北京防灾科技有限公司,北京101100 [3]河北省地震动力学实验室,三河065201

出　　处：《地震地质》2024年第3期589-607,共19页Seismology and Geology

基　　金：第2次青藏高原综合科学考察研究(2019QZKK0901)资助。

摘　　要：榆木山东缘断裂的晚第四纪构造变形及最新的活动特征反映了祁连山的向N扩展过程及印度板块向N挤压的远程碰撞效应。文中结合遥感影像解译、探槽古地震、无人机航空摄影测量和晚第四纪测年等方法,调查并新发现了榆木山东缘断裂的地表破裂带及其活动特征。结果表明,榆木山东缘断裂整体走向NW330°,现今的运动学特征以逆冲为主。以黑河为界,断裂的活动习性存在明显差异。在黑河口段(F_(1-1))发现了全新世晚期最新强震活动的地表破裂带。破裂带整体走向NW330°,倾向SW,长约10km,宽3~10m。地表破裂断错年轻的河流阶地、冲沟及台地,地表陡坎的最大高度为(3.3±0.2)m。光释光年代学结果显示,最新的地表破裂事件发生于(0.6±0.07)ka BP,经验公式估算其震级约为M 7.5。研究结果表明榆木山东缘断裂的变形特征为前展式逆冲推覆,其最新前缘的变形已经到达盆地内部。The Hexi Corridor in northwest China has obvious structural deformation and complex fracture image.With the development of several NW thrust fault zones accompanied by a large number of ancient earthquakes and historical seismic events,the earthquake disaster is relatively serious.The eastern margin of Yumushan fault is one of them.The fault is mainly developed in the east site of Yumushan Mountain,with the exposed fault plane striking NW330°and dipping about 41°~85°to the southwest as a whole.Previous research data show that the Eastern Margin of the Yumushan fault is an important part of the Qilian Mountain active thrust fault system in the northeast margin of the Tibet Plateau.It also constitutes the boundary structure between Hexi Corridor and Yumushan Uplift.Its late Quaternary tectonic deformation and recent activity characteristics reflect the northward extension process of the Qilian Mountains and the remote collision effect of the northward extrusion of the Indian Plate.However,there are still some controversies in the study of the latest activity age and deformation characteristics of the eastern Margin of the Yumushan fault zone,which directly affect the seismic risk assessment along the fault line and the Hexi Corridor,as well as the in-depth understanding of the active structural characteristics of the northeast margin of the Tibetan plateau.Combined with remote sensing image interpretation,paleoseismologic excavations,aerial photogrammetry of unmanned aerial vehicles and late Quaternary dating,this study carried out field investigations and newly discovered the surface rupture zone of The Eastern Margin of Yumushan Fault and its activity characteristics.The results show that The Eastern Margin of the Yumushan Fault strikes NW330°combined with obvious thrust movement,which is manifested as a fault scarp landform.That s revealing than the kinematics property of The eastern margin of Yumushan fault is dominated by thrust.The fault forms the dividing line between the Yumushan uplift and Zhangye Basi

关 键 词：榆木山东缘断裂 晚第四纪活动性 最新地表破裂 强震危险性 

分 类 号：P315.2[天文地球—地震学]