冲积扇河流阶地演化对走滑断裂断错位移的限定  

SLIP OFFSET ALONG STRIKE-SLIP FAULT DETERMINED FROM STREAM TERRACES FORMATION

作　　者：许斌斌 张冬丽 张培震 郑文俊 毕海芸 田晴映 张逸鹏 熊建国 李志刚 XU Bin-bin;ZHANG Dong-li;ZHANG Pei-zhen;ZHENG Wen-jun;BI Hai-yun;TIAN Qing-ying;ZHANG Yi-peng;XIONG Jian-guo;LI Zhi-gang(Guangdong Provincial Key Laboratory of Geodynamics and Geohazards,School of Earth Sciences and Engineering,Sun Yat-Sen University,Guangzhou 510275,China;State Key Laboratory of Earthquake Dynamics,Institute of Geology,China Earthquake Administration,Beijing 100029,China)

机构地区：[1]中山大学地球科学与工程学院,广东省地球动力作用与地质灾害重点实验室,广州510275 [2]中国地震局地质研究所,地震动力学国家重点实验室,北京100029

出　　处：《地震地质》2019年第3期587-602,共16页Seismology and Geology

基　　金：第二次青藏高原综合科学考察研究项目(2019QZKK0901);国家重点研发计划项目(2017YFC1500101);国家自然科学基金(41590861,41774049,41602224,41674051)共同资助

摘　　要：滑动速率是活动断裂定量研究的重要参数,是指在一段时间内断裂两盘相对运动的平均速度,是断裂带上应变能累积速率的重要表现,常被用于评价断裂的地震危险性。区域河流地貌特征及水系演化会受到构造活动的显著影响,因此分析河流地貌演化是研究构造变化特征的重要方法,也是限定断裂滑动速率较为可靠的方法。在总结河流地貌演化过程模式的基础上,考虑地形地貌因素的影响,建立了河流阶地位错模式和位错量的测量方法,并以阿尔金断裂东端断裂近垂直穿过的高岩沟为例,建立了其河流阶地的演化过程及其与断裂位错的关系,得到了不同阶地因断裂活动形成的位错量。结合前人的阶地测年结果,估算得到了阿尔金断裂在该段的水平滑动速率为(1.80±0.51)mm/a。Slip rate is one of the most important parameters in quantitative research of active faults.It is an average rate of fault dislocation during a particular period,which can reflect the strain energy accumulation rate of a fault.Thus it is often directly used in the evaluation of seismic hazard.Tectonic activities significantly influence regional geomorphic characteristics.Therefore,river evolution characteristics can be used to study tectonic activities characteristics,which is a relatively reliable method to determine slip rate of fault.Based on the study of the river geomorphology evolution process model and considering the influence of topographic and geomorphic factors,this paper established the river terrace dislocation model and put forward that the accurate measurement of the displacement caused by the fault should focus on the erosion of the terrace caused by river migration under the influence of topography.Through the analysis of the different cases in detail,it was found that the evolution of rivers is often affected by the topography,and rivers tend to migrate to the lower side of the terrain and erode the terraces on this side.However,terraces on the higher side of the terrain can usually be preserved,and the displacement caused by faulting can be accumulated relatively completely.Though it is reliable to calculate the slip rate of faults through the terrace dislocation on this side,a detailed analysis should be carried out in the field in order to select the appropriate terraces to measure the displacement under the comprehensive effects of topography,landform and other factors,if the terraces on both sides of the river are preserved.In order to obtain the results more objectively,we used Monte Carlo method to estimate the fault displacement and displacement error range.We used the linear equation to fit the position of terrace scarps and faults,and then calculate the terrace displacement.After 100,000 times of simulation,the fault displacement and its error range could be obtained with 95%confidence

关 键 词：河流层状地貌 走滑断裂 断错位移 地形效应 阿尔金断裂 

分 类 号：P315.2[天文地球—地震学]