Evolution Process Of Kanas Lake In Xinjiang,Altai

Altai Kanas River Valley is located in Kazakhstan,China,Russia and Mongolia four at the junction of the south slope of Altai Mountains,during the Quaternary period,glaciers in Kanas River Valley developed large-scale advance and retreat,and leave the Kanas Lake.Kanas Lake is a large glacial lake in China,the study of its origin and process not only plays an important role in the Kanas River Basin,but also has an important significance for the entire Altai region.The through Kanas Lake outlet glacial deposits of geomorphology,sediment profile morphological characteristics,sedimentary environment characteristics,and the use of electron spin resonance(ESR)dating,further analysis of the causes of the Kanas Lake,discuss the evolution of the Kanas Lake.Research results show that:Since the Late Cenozoic Tectonic and glacial dual role of Kanas Lake.The main evidence is:(1)under the action of tectonic stress,Altai Kanas river basin developed near the Northeast southwest trending fault zone,the formation of the embryonic form of the Kanas Lake;in the Middle Pleistocene,Altai region and develop the large-scale tectonic movement,in Kanas Lake in the middle and downstream area appeared a plurality of reverse faults,the Kanas Lake morphology difference,but also for Kanas Lake outlet sediment sources.(2)the last glacial Kanas Lake outlet has three groups of terminal moraine,contains the many end moraine.Among them,the third group terminal moraine including 4-5 moraine,the second group of end moraine including 7-8 moraine,first set of end moraine including 6-7 bar end moraine,such landform composition should be for repeated glacial advance and retreat of Kanas Lake outlet sediments were pushing and thrusting nappe,will appear up to more than 15 of the moraine.On each moraine ridges of fine grain size analysis results show that the and"second" glacial sediments of contrasting,Kanas Lake outlet sediment particles are fine and uniform,compact structure is digging glacier erosion grinding results.At the same time,the structural characteristics of the sedimentary profile in Kanas Lake outlet also proved the existence of repeated glacial erosion.The evolution process of Kanas Lake was restored according to the cause of Kanas Lake.From the late Paleozoic Hercynian orogeny and late Tertiary Himalayan tectonic movement laid the Kanas Lake of the overall trend,the Northeast southwest trending faults formed rudiment of Kanas Lake,during the 219±44 ka,the Quaternary glaciers developed on a large scale and in during the Middle Pleistocene Altai region appear large-scale faults,in Kanas midstream and downstream areas appeared two obvious northwest southeast trending reverse faults during glacial erosion grinding fault plane and the fine sediment transport to the Kanas Lake outlet,to Kanas Lake sediment sources.From 76±16 ka to 28±4 ka during the last glacial period,fluctuation of ice into ice retreat push the Kanas Lake sediments,accumulate in the upper part of the glacier sediment,the sediment at the bottom of the glacier grinding dig erosion,sediment particles thinner,low porosity,easily permeable,blocking the river Kanas Lake form provide a good resistance to water conditions.Thereafter glaciers continue to retreat,the Lake gradually exposed,glacier meltwater,atmospheric precipitation gradually converge in the basin,in 28±4 ka to 6.8 ka period,the lake basin was filled with ice to meltwater,forming Lake Kanas now.