The Geomorphology Of The Ghez River Drainage Basin,Eastern Pamir,and Its Relationship With Regional Tectonics

River is an important element in geomorphology.River geomorphologic evolution is mainly controlled by regional tectonics,and record the corresponding tectonic activities.Analysis of the river geomorphologic characteristics can reveal the interaction between regional tectonic evolution and geomorphologic evolution.Pamir is located in the northwest of the Tarim basin,and strongly deformed by the India-Eurasia collision and the continued convergence.The activity of its regional structure and its control of geomorphologic evolution are the focus in recent studies.There are series of faults with different properties and strikes developed in eastern Pamir in China,these active tectonics in this region show the strong spatial difference,they have the strong control effect on the geomophology.In this study,we focus on the Ghez river drainage basin in order to reveal the differences in the tectonic activities of the local structures and the impact of regional structures on the river evolution.The Ghez River is originated from the eastern Pamir,and flows across some major fault zones in eastern Pamir.By extracting the geomorphologic features of the Ghez drainage basin from the 90 meter-resolution DEM data,this study revealed the spatial distribution characteristics of east Pamir tectonic activity.Furthermore,the river profile characteristics of the Ghez river were analyzed to discuss the origin of the Ghez river,together with numerical simulations.The following conclusions are drawn:(1)There is almost no significant contrast in ? across water divides,indicating that the drainage network topology is in stable state.(2)The spatial distribution of the river steepness index in the Ghez river has three characteristictis as following:a.the river steepness index in the region between the Kongur Shan Extensional System and the Main Pamir Thrust is higher than on the both side of this region;b.in the region between the Kongur Shan Extensional System and the Main Pamir Thrust,the river steepness index in the south region is higher than the north region.c.the trunk of the Ghez river between the Kongur Shan Extensional System and the Main Pamir Thrust has the highest river steepness index.(3)The river steepness index reaches the highest in the region between the Kongur Shan Extensional System and the Main Pamir Thrust and it means that the extension of the Kongur Shan Extensional System and the thrust of the Main Pamir Thrust have strong controls on uplift and it caused the highest uplift rate and the highest river steepness index.Besides,the river steepness index in the south of the region between the Kongur Shan Extensional System and the Main Pamir Thrust is higher than in the north,and thus it indicates that uplift rate in the south is higher than the north;the Ghez river and its adjacent areas between the Kongur Shan Extensional System and the Main Pamir Thrust show the steepest river steepness index in the whole basin,which indicates that the erosion rate and tectonic uplift rate in this region are the highest in the whole basin.(4)The spatial distribution characteristics of the river steepness index is coincident with the vertical activity difference of faults in different sections of the Kongur extension system and the uplift,erosion pattern of the domes,however,the horizontal extension of the active faults has little effect on the spatial distribution of the river steep index.(5)By comparing the river morphology and the river steepness index between the main stream and its adjacent tributaries,this study proposed that the Ghez river is possibly an antecedent river in this region.On this basis,two models,which set the Ghez river as an antecedent river and capture river respectively,were run by FastScape software in this study.The results of the two models also demonstrate that the Ghez river is possible an antecedent river.