利用构造地貌分析日月山断裂晚更新世以来的演化  

ANALYSIS OF EVOLUTION OF THE RIYUESHAN FAULT SINCE LATE PLEISTOCENE USING STRUCTURAL GEOMORPHOLOGY

作　　者：李智敏[1,2] 李文巧 殷翔[1] 黄帅堂[3] 张军龙 LI Zhi-min;LI Wen-qiao;YIN Xiang;HUANG Shuai-tang;ZHANG Jun-long(Qinghai Earthquake Agency,Xining 810001,China;Shenzhen Academy of Disaster Prevention and Reduction,Shenzhen 518003,China;Earthquake Agency of Xinjiang Uygur Autonomous Region,Urumqi 830011,China;Key Laboratory of Earthquake Predication,Institute of Earthquake Forecasting,China Earthquake Administration,Beijing 100036,China)

机构地区：[1]青海省地震局,西宁810001 [2]深圳防灾减灾技术研究院,深圳518003 [3]新疆维吾尔自治区地震局,乌鲁木齐830011 [4]中国地震局地震预测研究所,地震预测重点实验室,北京100036

出　　处：《地震地质》2019年第5期1077-1090,共14页Seismology and Geology

基　　金：青海省科技计划项目(2017-ZJ-775);中央级公益性科研院所基本科研业务专项(JB-18-03);国家自然科学基金(41372215)共同资助

摘　　要：日月山断裂位于东昆仑断裂和祁连-海原断裂等主边界断裂控制的柴达木-祁连活动块体内部,属于二级构造。该断裂构造地貌发育,研究其活动特征可获得青藏高原东北缘向外扩展的信息。文中以晚更新世以来清晰的地貌变形为重点,通过RTK测量方法获得沿断层走向的垂直位移量,基于断层生长连接理论,分析了日月山断裂的演化,并讨论其反映的动力学背景,主要获得了以下3点认识:1)根据晚更新世以来洪积扇和阶地等地貌内长约200km的3期断层陡坎的发育特征,将日月山断裂分为5段,最重要的分段位于第三重叠区(CD-3)。2)日月山断层3期位移量分布形态反映了断层由多条次级破裂生长连接而成,处于断层生长连接的第二阶段。以CD-3为界,NW侧的断层持续生长连接;东南侧的断层活动时间相对较短,活动强度相对较弱。3)断层位移量分布曲线极值指示了应变集中和应力积累的位置。以CD-3重叠区为界,NW侧应力和应变主要集中在中部及断层重叠区,东南侧应力长期积累的范围则相对分散。应力状态可能与区域构造应力挤压作用下块体内部的顺时针旋转有关。The northeastern margin of Tibetan plateau is an active block controlled by the eastern Kunlun fault zone,the Qilian Shan-Haiyuan fault zone,and the Altyn Tagh fault zone.It is the frontier and the sensitive area of neotectonic activity since the Cenozoic.There are widespread folds,thrust faults and stike-slip faults in the northeastern Tibetan plateau produced by the intensive tectonic deformation,indicating that this area is suffering the crustal shortening,left-lateral shear and vertical uplift.The Riyueshan Fault is one of the major faults in the dextral strike-slip faults systems,which lies between the two major large-scale left-lateral strike-slip faults,the Qilian-Haiyuan Fault and the eastern Kunlun Fault.In the process of growing and expanding of the entire Tibetan plateau,the dextral strike-slip faults play an important role in regulating the deformation and transformation between the secondary blocks.In the early Quaternary,because of the northeastward expansion of the northeastern Tibetan plateau,tectonic deformations such as NE-direction extrusion shortening,clockwise rotation,and SEE-direction extrusion occurred in the northeastern margin of the Tibetan plateau,which lead to the left-lateral slip movement of the NWW-trending major regional boundary faults.As the result,the NNW-trending faults which lie between these NWW direction faults are developed.The main geomorphic units developed within the research area are controlled by the Riyueshan Fault,formed due to the northeastward motion of the Tibet block.These geomorphic units could be classified as:Qinghai Lake Basin,Haiyan Basin,Datonghe Basin,Dezhou Basin,and the mountains developed between the basins such as the Datongshan and the Riyueshan.Paleo basins,alluvial fans,multiple levels of terraces are developed at mountain fronts.The climate variation caused the formation of the geomorphic units during the expansion period of the lakes within the northeastern Tibetan plateau.There are two levels of alluvial fans and three levels of fluvial terrace

关 键 词：青藏高原 日月山断裂 晚更新世 几何分段 断层生长 

分 类 号：P315.2[天文地球—地震学]