Geomorphological Process Of Late Quaternary Glacier In Kanas Valley In The Altai Mountain

The southern slope of Altai located in the north of Xinjiang Urumqi Autonomous Region of china. The Kanas River originates on the southern slope of theYouyi Peak, The glaciers have been advanced and retreated dramatically during the glacial-interglacial in Kanas River valley.Glacial erosive and accumulative landforms are not only very important for the analysis of the regional geomorphological process but also meaningful for the research of global change. This study adopts the field topography actual inspection, special tills ESR sampling, Kanas valley platform and topography measurement, the highest glacial boulder statistical, the indoor sample processing analysis and data analysis, to studies the quaternary glacial geomorphology evolution sequence, evolution of size and simulate the evolution scale of glacier in Kanas River valley.According to the field investigation on the Quaternary geomorphology in the lower part of the kanas lake exit in main valley, this paper measured the altitude of multiple level U-shaped valley in different regions and confirmed the highest limit of glacial boulders and its distribution position. Using the electron spin resonance(ESR) method, we dated the glacial tills of the different moraines preserved along the main valley. Results of the glacial sequences, extent and glacial geomorphological process showed that four glacial advances took place in the lower part of the Kanas valley. Compared with the former research results, these glaciations can be assigned as the Zhonglianggan glaciation, corresponding to the marine isotope stage 12(MIS12), MIS8/10 glaciation, Penultimate glacition(MIS6), and the last glacial cycle(LGC). LGC glacial advance can be further divided into three stages which correspond to MIS 4, 3, and 2. Based on the distribution of the three level U-shaped valleys, we concluded that extent of glaciers decreased with time. The thickness of the glacier during the Zhonglianggan glaciation was 50~395m from the Glacial Station to the end of the glacier, and the length and width are also the largest at that time. The three dimension extent showed that the glacier distributed in the main valley and in the both side ridges. The thickness were 102~199m and 88~269m during the MIS8/10 and the Penultimate glaciation, and the glacier reached near the Tuojingwan district. Combined with the ceiling of the highest boulder and actual landscape, painting the size range of each sub-glacier and making the chart of valley glacier evolution.Also found: valley slope terraced landforms and main valley terraces topography have vary widely at the intersection of main valley of kanas lake exist to yazehu and black lake tributary.Well persevered multiple level U-shaped valley bottom in the eastern slope of main valley near the region of Yaze lake and old tuva village indicated that the quaternary glaciers have the great activity, flowability and continuity. In addition, polished surface of the moutonnee back and multi-level distributed of cirque shows that the glacier has the properties of temperate type.Clear asymmetry happened in the Kanas main valley. The east slope of main valley of kanas has mostly preserved terraces,with many glacial boulders. but it is talus with taiga formed by debris bedrock in the west slope. Combined with analysis of other typical valley regions, studies suggest that the development of the glacial valley was affected by the regional climate and the topography.