Study On The Development Of Drainage System And Active Structure In The Southeast Of Dengkou In The Hetao Area

The active structure has intermittent characteristics.Based on tectonic landform evolution's sentive impact on tectonic uplift,geomorphic characteristics of river gradually become ideal information carriers of neotectonics.Therefore,the tectonic movement and the topographic evolution can be tracked by studying the geomorphology of the watersheds and the drainage system.DEM,remote sensing data and geophysical data are used to extract the drainage system and geomorphic indices of the study area,and to interpret the fault structure,based on detailed field geological survey.Finally,the relationship between the development of the drainage system and the active structure in the southeast of Dengkou is discussed from two aspects: the distribution of drainage system and the development of fluvial landform.The following conclusions have been achieved:1)Using DEM,remote sensing image and geophysical data,the structures of the study area are interpreted and verified.The results show that there are two groups of active faults,the Dengkou–Benjing fault and Zhuozishan fault,both of which are characterized by high slope and fluctuation.2)Comparing the network of the river with fault structure,as well as the density map of the drainage network with the figure of Bouguer gravity anomaly,it is found that the active structure has an obvious control effect on the distribution of the drainage network in the study area.The density of the drainage network is highly correlated to the Bouguer gravity anomaly.The Dengkou-Benjing fault made the piedmont develop a series of deep undercut horizontal drainage system.On account of the Zhuozishan fault,parallel drainage system and dendritic drainage system are developed in the west and the east of the study area,respectively.3)Based on the Hypsometric integral(HI),it is found that there are differences in the geomorphic development stages in the east and west watersheds of the study area,and the asymmetric development pattern is mainly affected by tectonic factors.On the one hand,from the early to the end of the late Pleistocene,there is differential uplift in the northwest margin of Ordos block(where the study area is located),and the uplift amplitude in the west of the study area is larger than that in the east.On the other hand,the western section of the Benjing-Dengkou fault across the study area is more active than that of the eastern section,and the uplift in the west of the study area is larger due to the effect of the Zhuozishan fault.Based on the multi-source data and field investigation,this study interprets the geological structure,extracts the geomorphic indices,and analyzes the relationship between the development of the drainage system and active structure in the study area.It not only strengthens the study of the controlling effect of active structure on the surface process,but also supplements the data for the structural study of the southern boundary of the Hetao area.