Geomorphological Evolution And Landscape Characteristics Analysis Of The Minhe Basin In The Northeastern Margin Of The Qinghai-Tibet Plateau

Minhe basin is located in the eastern section of Middle Qilian block of Qilian structural belt.The geological environment is quite complex and the tectonic activities are quite intense.From the Paleozoic,the region experienced many times of block collision and splicing process,to the Mesozoic basin received a large amount of continental deposition,and then to the Cenozoic intense denudation and planation.It can be said that the Minhe region has experienced complex geographical evolution in the long geological history.This paper mainly starts from the geomorphologic evolution,and through field investigation,experimental analysis and combining with the existing research results,systematically analyzes the evolutionary background of the main basin development period of Minhe Basin,the current topographic and geomorphological characteristics,the development characteristics of river system and the typical regional geomorphological landscape types.The stratigraphic distribution in this region is relatively complex,and the red bed has a large scale,and a certain number of Danxia and colored hills have been formed in the landscape.As a terrestrial clastic rock deposit,the red bed is the material basis for the development of landscape geomorphology in this region,and it is an unavoidable content in the study of the geomorphological evolution of Minhe Basin.In this paper,the structural characteristics of the study area and the lithology,lithofacies and distribution of the stratigraphic development are systematically described,and the influencing factors of its formation are analyzed.On this basis,GIS method and sedimentology method are used to study the regional topographic and geomorphic parameters,to judge the process of macroscopic geomorphic evolution,and to analyze the influence of this evolution process on the development of typical geomorphic landscape in the study area.The main conclusions are as follows:(1)Since the late Cenozoic,the geomorphic evolution of the Minhe Basin was mainly controlled by the intermittent uplift of the Qinghai-Tibet Plateau,during which the river system pattern was continuously reorganized,leading to the continuous evolution of the sedimentary environment and the erosion environment in the basin.(2)today in minhe basin landform features,mainly by qilian mountains lung in the process of the raw waste of lateral compressive stress,makes the whole basin elevation by the big board mountain,La Ji Shan piedmont zone northwest to southeast direction,slow down,and the development of drainage process is the most favorable evidence to support this conclusion,is located in the central basin in the south,almost things towards Huang Shui He six river terraces to the development in the north,but only 3 in the south,and more of the steep valley landforms,drainage distribution pattern shows the characteristics of obvious asymmetry of river basin.At the same time,the river system in the basin is mostly developed to the north of the tributaries,almost not developed in the south.(3)In the analysis of the area elevation integral(HI)of the basin,it is found that the overall evolution stage of the basin is in the "prime stage",and the value shows a decreasing trend from the edge of the basin to the main river,indicating that the tectonic activity of the basin decreases from the edge to the middle.(4)The red-bed landscape in the basin is mainly dominated by Danxia and Colory-mound.Through the superposition analysis of the distribution pattern of regional geomorphic landscape and the distribution characteristics of river system,it is found that the formation and extinction process of the regional geomorphic landscape depends heavily on the hydrodynamic conditions and develops rapidly.In general,complex tectonic environment and a variety of continental clastic rock the huge amount of sediment,for the formation of landscape laid a good foundation,frequent tectonic movement of geomorphic evolution provides ample endogenous impetus,the unique geographical environment and dense shade for typical landscape shape to create a good external dynamic conditions.