Study On The Quaternary Glacial Geomorphic Features Of The Gong Wang Mountain In Kunming, Yunnan Province

Gongwang Mountain is located in the northern part of the "Central Yunnan Lake Basin Karst Plateau Subregion" in the geomorphologic regionalization of Yunnan Province.It is a watershed between the Pudu River and the Xiaojiang River basin,and is composed of sandstone.The lithospheric uplift of limestone and basalt is one of the highest mountains in the northern hemisphere.The study of Quaternary glacial landforms in Gongwang Mountain is of great significance in understanding the development conditions of Quaternary glaciers in eastern China,the evolution process of tectonic-climate,and the integrity and regional continuity of the reconstruction of paleoclimate environment.In recent years,with the development of remote sensing and photogrammetry,the investigation of Quaternary glacial landforms has provided an important,rich threedimensional analysis data base and advanced means.The combination of digital elevation model and remote sensing image is not only a mathematical expression of terrain and geomorphology,but also a direct,accurate and realistic reflection of the true form of Quaternary glacial landform,and it can lay a foundation for the quantitative expression of Quaternary glacial landform.Based on field investigation and visual interpretation of 3D remote sensing images,the distribution and regularity of glacier landforms in Quaternary period in the study area are described qualitatively,with emphasis on the quantitative study of glacial erosion landform ice bucket and glacial trough valley.On the basis of the determination of glaciation range,the conditions of Quaternary glacier development in Gongwangshan were preliminarily analyzed.The results are as follows:Quaternary glaciation occurred in the mountainous area above 3100 m above the elevation of Gongwang Mountain,and the glacial landform remains are well preserved.The bedrock in this area is dominated by Permian Emeishan basalt,and the Quaternary glaciation occurred in this basic lithology,the Quaternary glacial geomorphology is mainly concentrated in three areas near Yaojintang Niu Dongping,Xueling Mountains and Jiaozi Mountain.Most of them appear in the form of glacial geomorphology after combination.By means of statistical analysis,it is concluded that the aspect ratio of ice bucket is between 0.6 and 1.47,which is approximately equidistant on the plane,and good hydrothermal conditions can promote the ice bucket to grow actively and make its aspect ratio smaller.However,the ice hopper under the unfavorable water and thermal conditions can only be passively adapted and its aspect ratio is larger.The geomorphology of glacial trough valley is analyzed by combining field geomorphologic investigation with model analysis.The results show that in the parabola model of Yanzhidong trough valley,A value varies from 1.201 to 12.1305 and B value varies from 0.9734 to 3.3054,and changes with elevation from high to low.There is a rule that the glacial trough valley evolves at 3390 ~ 3420 m above sea level and then becomes larger,which reflects that the evolution of glacial trough valley does not accord with the normal state at 3390 ~ 3420 m above sea level.It is concluded that lithologic differences and river traceability erosion are the main reasons for affecting the channel valley shape.Compared with the ice hoppers developed in 12 regions at the same latitude,it is found that under the control of different climatic conditions,structural factors,landforms,slope slopes and lithologic conditions,there are not only some common features,but also differences between them.