Study On The Determination And Influencing Factors Of ELA In Western Sichuan Of Late Quaternary Period

The Qinghai-Tibet Plateau is the largest modern glacier distribution area in the middle and low latitudes of the world.The glacier development scale,timing and snowline height since the Quaternary is an indicator of global past and modern climate change.The western part of the Qinghai-Xizang Plateau is located at the junction of the plateau and the basin.At the junction of the plateau and the Late Quaternary,there are many ice events,which are the height of the mountain and the glacier balance line(ELA),Verify the glacier development climate and the structural coupling model of the key areas.Based on the field stratigraphy,geomorphologic investigation and ESR dating results,this paper uses the comprehensive factor to calculate the modern material balance line,and uses the CF method,THAR,MELM method and TSAM method.The calculation method of the material balance line is used to determine the height of the glacier balance line in different ice stages since the late Quaternary period,and the factors influencing the height of the control balance line are analyzed.The specific results are as follows:1.Using the comprehensive factor method to calculate the height of modern glacier material balance line,considering the principle of space distance and altitude above the average maximum precipitation height,the Xiaoxiangling Mountain area selects the Yuexi County weather station as the starting point and calculates the modern snowline height of4875.5 M,Luoji Mountain selection Zhaojue weather station as the base point,modern snow line height of 4847.8m.The results show that the ELA of the east slope is 3402 m and the west slope is 3545 m in the second glacial period(MIS6),and the ELA is 3585 m in the early glacial period(MIS4)The slope is 3645 m,the last ice age(MIS2)is 3960 m and the west slope is 4144 m.On the whole,the elevation of ELA is higher than that of east slope 100 ~ 200 m since the late Quaternary glacial period.In the Kunlun ice age(MIS 16/12),the ELA is 3775 m,the MIS 6is 3380 m,the MIS4 is 3706 m,and the MIS2 is 3494 m.The results show that the height of the glacier material in the Xiaoxiangling and Luoji Mountain is consistent with the overall law of the distribution of the snow line during the Quaternary glacial period in the eastern margin of the Qinghai-Tibet Plateau.Which is not only closely related to the climatic and tectonic conditions since the Quaternary of theQinghai-Tibet Plateau and its surrounding mountains,but also influenced by topographic factors such as sea level rise and fall,slope and aspect.