Late Quaternary Glacier Scale And Palaeoclimate Quantitative Reconstruction In Xiaoxiangling,western Sichuan

Since the Earth's history entered the Quaternary period,the global climate has changed between cold and warm,it has become the most important feature.During the glacial and interglacial periods,abundant glacial remains were left in the glaciated area,which not only played an important role in restored the modern and ancient material balance lines in the glaciated area,but also provided important geomorphological support for the reconstruction of glacier scale and palaeoclimate of mountain glaciers.Xiaoxiangling located in the western of Sichuan,the east of Hengduan Mountains,mountain region in more than 2300m remains the quaternary glacial relics.The Quaternary glacial topography distribution,ice age series,ancient climate characteristics and glacier size were discussed,which not only help research the Qinghai-Tibet Plateau edge mountain Hengduan Mountains,especially evolutionary history of the Quaternary,and its further enrich the paleoclimate information of global climate change since the Quaternary period.In this paper,the long valley in east of Xiaoxiangling was selected as study area,Panxi Plateau,field geomorphological investigation method and laboratory simulation analysis were used,which was reconstructed paleoclimate and glacial scale since the third glacier advance of Quaternary period,and the evolution history of the Quaternary glaciers in this area was restored.The main conclusions were as follows:(1)Based on the comprehensive factor method,the height of mass balance line of modern glacier in Xiaoxiaoling was reconstructed,and the reconstructed result was 4864.5m.The height of mass balance line of the paleo glacier was reconstructed by CF method,THAR method,AAR method and AABR method since MIS 6,MIS 4 and LGM,and the reconstructed results were 3323m,3532m and 3745m,respectively.Based on the P-T model and LR model,combined with the existing paleoclimate data,the temperature and precipitation conditions during the glacier advance of MIS 6,MIS 4 and LGM in the Xiaoxiangling were reconstructed.The simulation results showed that when the precipitation ratios were 60?80%,50?80%and 10?50%,the temperature reduction values were8.19?9.66?,7.11?9.67?and 6.41?16.86?,respectively.(2)Based on the glacier dynamics model,the"GLa Re"tool was used to restored the glacier scale in the long valley of Xiaoxiangling during the third ice advances.The results showed that the average thickness of the glacier scale from the MIS 6 to the LGM were73.16m,72.16m and 70.59m,respectively.The areas were 9.3km~2,5.3km~2,and 5.25km~2,respectively;The volumes were 0.679km~3,0.39km~3and 0.37km~3,respectively.According to the above results,from the perspective of glacial scale,the glacial scale,the glacier thickness,area and volume of Xiaoxiangling had been decreasing gradually since the MIS 6.(3)The driving factors of glacier advance in the MIS 6 were the strengthening of monsoon,the increasing of precipitation and the lower temperature.Compared with the MIS6,the global temperature decreased and the glacier scale expanded in the MIS 4,which showed that driving factors of the glacier advance in this stage were the influence of lower temperature and more precipitation.The LGM corresponded to the Heinrich2 event,which showing a significant weak monsoon event in the southeastern of the Qinghai-Tibet Plateau,the climate was became cold and dry.Thus,the main driving factor of glacier advance in the LGM was the temperature decrease,which was caused by weak monsoon event.