Baima Snow Mountain Quaternary Glacial Geomorphology And Preliminarily Divides The Ice Age

Baimaxueshan located in the middle part of Hengduan range, which is the watershed ofthe Lancang River and Jinsha River among the three parallel rivers area honored with thefamous and the largest area of China World Heritage Sites. Affected by the southwestmonsoon and local complicated topographic condition, the climate in Baimaxueshan changesfrom the cold climate of the modern glacier area at the height of4500m to the dry and hotclimate distribute at the Jinsha River valley at about2000m whose precipitation only200mm,which indicate the vertical zonation is especially notable. Extensive and typical glaciergeomorphologies are integrated preserved above3900m at Baimaxueshan. Study of theQuaternary glaciation in Baimaxueshan is significant not only on recovery the localpalo-climate and environment, but also in explaining the relationship between climate andtectonic uplift.Based on the field investigation of the glacial sediments in Baimaxueshan and the featureof the erosion geomorphology like cirque, valley and sediment geomorphology such asterminal and lateral moraine preserved above3900m, we believe that the study area hasexperienced three major glacial advances since the last glacial cycle, that is the early stage oflast glacial cycle, the last glacial maximum (LGM) and the neoglaciation in Holocene. CF andTHAR methods are applied to calculate the palo-ELAs in different stage. The results are~4642m,~4360m and~4034m respectively responding to the Nerglaciation, the LGM and theearly stage of last glacial cycle. Compared with the glacier sequence of other mountains inHengduan mountain range, we discovery that the timing of the glaciation in differentmountains located at the same planation surface in Tertiary have great difference. It is thetectonic uplift coupled with the climate change that led the Mountains to the snowline andwitnessed the glacial advance.Moreover, compared with the other mountains of the environmental magnetism of theglacial deposits, the magnetic susceptibility of Baimaxueshan is between5.56and11.60,which is too small. It indicates that the affected factors on the glacial deposit are not only themother lithology, but also the complicated climate conditions. At the same time, it isindirectly reflect the relative dry and cold climate in Baimaxueshan in the last glacial cycle. Itis consistent with the phenomenon that the huge mountains in the west of Baimaxueshan likethe Meilixueshan obstruct the precipitation taken by the southwest monsoon.