Abstract: 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 interval. We selected the Gaoyan River in the eastern Altyn Tagh Fault as the research object, and used the unmanned air vehicle aerial photography technology to obtain the high-resolution DEM of this area. Based on the terrace evolution model proposed in this paper, we analyzed the terrace evolution with the detailed interpretation of the topography and landform of the DEM, and inferred that the right bank of the river was higher than the left bank, which led to the continuous erosion of the river to the left bank, while the terraces on the right bank were preserved. In addition, four stages of fault displacements and their error ranges were obtained by Monte Carlo method. By integrating the dating results of previous researches in this area, we got the fault slip rate of(1.80±0.51)mm/a. After comparing this result with the slip rates of each section of Altyn Tagh Fault studied by predecessors, it was found that the slip rate obtained in this paper is in line with the variation trend of the slip rate summarized by predecessors, namely, the slip rate gradually decreases from west to east, from 10~12mm/a in the middle section to about 2mm/a at the end.

Key words: offset stream terraces, strike-slip fault, slip offset, topographic effect, Altyn Tagh Fault

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。

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