Study On The Active Tectonic Geomorphology Of Aba Basin In Western Sichuan

China is located in an active area of the tectonic activity,forming a variety of active tectonic geomorphic types.With their strong activities since the late Cenozoic,various types of active folds and active faults have developed,and frequently lead to destructive earthquakes and various geological disasters.The study of active tectonic geomorphology can deduce the movement characteristics of the crust in a certain period of time,and obtain the data of the amplitude,interval time and rate of tectonic activity,which is of great significance for geological disaster prevention,earthquake prediction and safety evaluation,and location selection of major projects.In this paper,Aba basin in Western Sichuan Province is taken as the research area.Based on the previous research data,ASTER-DEM data and Arc GIS spatial analysis technology are used to extract the elevation,slope,topographic relief,elevation strip profile and other information of the research area,and analyze the characteristics of active tectonic topography of ABA basin.The following conclusions are obtained:(1)Through the extraction and statistics of elevation,surface slope,relief and other elements,the spatial analysis of the distribution of topography and geomorphology in Aba basin is carried out,and elevation simulation map,slope classification map and relief classification map are made.Through the elevation simulation map,it is found that in the area with strong tectonic activity,the fault activity will cause strong relief of terrain,resulting in significant changes of terrain elevation on both sides of the fault.(2)Through the comparison of elevation simulation map and slope classification map,it can be found that the terrain elevation and surface slope in the study area have obvious correlation,and the terrain with large elevation value,such as mountains,has a larger surface slope value;the terrain with small elevation value,such as basins,plains and hills,has a smaller surface slope value.In the area where the surface slope changes strongly,the corresponding terrain elevation also changes strongly,and these places are often controlled by large-scale faults or related to structural activities,such as faults in Aba basin.(3)The geomorphology of the study area is obviously controlled by the NW-SE faults,in which the NW area is uplifted,forming a mountainous geomorphology;the area is relatively decreased,mainly showing high-altitude plain and hilly geomorphology.Secondly,due to the difference and intermittence of the ascending and descending movement,there are many layered landforms in the area,including the fourth level planation plane and the third level terrace.(4)According to the 1:250000 Regional Geological Survey Report of Aba County,the ESR age values of quartz in class III,II and I terraces are 121 ka,60ka and 20 Ka respectively.According to the field geological survey,the relative River pull-out heights of class III,II and I terraces are 40 m,10m and 3m respectively.Through calculation,the average lifting rate of class III terrace is 0.49m/ka,that of class II terrace is 0.18m/ka,and that of class I terrace is 0.15m/ka.