Geomorphological Morphological Features Of Yarla Shampo And Its Adjacent Areas Since Pleistocene In Southern Part Of The Tibetan Plateau

The collision and extrusion between the Indian plate and the Eurasian plate triggers strong uplift of the Tibetan Plateau.The Tibetan Plateau,which forms the strongest collision orogenic belt of global crustal activity,becomes the most developed region of Quaternary glaciers in the middle and low latitudes.Geomorphic morphology is not only the result of the interaction between tectonic movement and erosion,but also an important carrier of crustal deformation,water system evolution,climate change and other processes.One of the core contents of current research on Tibetan Plateau is how to reveal the complex coupling relationship between internal and external forces based on geomorphic morphological features.Located in southern part of the Tibetan Plateau,Yarla Shampo and its adjacent areas are abundant in tectonic movement,glaciers,rivers and lakes geomorphic types,containing much information that can reveal the Quaternary environmental evolution.It’s an ideal area to explore the interaction between tectonic movements,geomorphic processes and climate changes.At present,geomorphic morphological features in this region are rarely explored by combining ancient and modern methods and spatial analysis.Based on DEM data,with Arc GIS 10.2 software as the operating platform,the paleo-surface of the Pleistocene period in the study area was reconstructed and the erosion amount was calculated.Apart from that,the influence of tectonic movement and glaciation on the geomorphic morphology of the study area since the Pleistocene was discussed.Based on large-scale and small-scale watershed,the significance of Hypsometric Integral on tectonic movement,lithology distribution and glaciation in the study area and its area and spatial dependence were explored.The longitudinal profile morphology of major rivers and local rivers were extracted and function fitting were carried out.The corresponding river length slope index and Hack profile were plotted.According to the results:(1)The present geomorphic morphology of the study area was basically fixed in the Pleistocene period.The tectonic uplift and erosion rate in the eastern and southern parts of the area were greater than those in the western and northern parts.Glaciation caused by climate change in the early Holocene led to the short-term diversion of the Siqu Nama River,which affected the geomorphic morphology of the study area.(2)The Hypsometric Curve of the study area is dominated by "S" type,which is in the prime stage of geomorphic evolution.The present geomorphic evolution process is dominated by tectonic movement.Glaciation is transforming the local geomorphic morphology in the study area on a small scale.(3)In the large-scale watershed,the Hypsometric Integral values indicate that the active fault of Langxian fault is the strongest,followed by the Yarla Shampo fault,and the Zhegu fault is the weakest.In the small-scale watershed,the Hypsometric Integral values indicate that the erosion resistance of granites in the study area is the strongest,followed by that of quartz sandstone and diorite,that of sandstone and limestone is in the middle,that of silty rocks is weak,but that of Quaternary sediments is the weakest.(4)In the large-scale watershed,the area dependence of Hypsometric Integral in the study area is mainly affected by tectonic movement and less affected by spatial dependence.In the small-scale watershed,the area of sub-watershed and Hypsometric Integral values are not correlated.The spatial dependence is reflected in that the height difference has a certain influence on the Hypsometric Integral values.(5)The longitudinal profile morphology of the main rivers in the study area have a high degree of fitting with the linear function or exponential function,and the convex is obvious on the Hack profile,the whole study area is greatly affected by tectonic uplift.The longitudinal profile morphology and Hack profile of local rivers reveal the activity of the middle and southern sections of the Yarla Shampo fault is stronger than that of the northern section.