四川康定折多山末次冰盛期古冰川重建及其气候意义

Reconstruction of glacial extent of the Zheduoshan Mountains,eastern Qinghai-Tibet Plateau and its climatic implications

折多山位于青藏高原东缘,地势上处于由高原面向高山峡谷的过渡区,古冰川遗迹保留较好。对折多山冰川地貌进行深入研究,对揭示青藏高原东缘地形演化与古气候变化的耦合机制具有重要意义。在野外考察的基础上,结合Google Earth遥感影像、《中国第二次冰川编目》和DEM等资料,对折多山冰川地貌及其特征参数进行了识别、提取和计算。研究共识别出189条古冰川,覆盖面积为497 km^(2)。基于研究区已有年代学资料,本区冰川地貌主要为末次冰盛期(LGM)以来冰川作用遗存。恢复研究区LGM冰川平衡线高度(ELA),在西坡和东坡分别为4380 m和4110 m,相差270 m,揭示出分水岭东侧更有利于冰川发育。广泛发育的冰蚀湖、冰蚀基岩面、羊背石等,以及深切的冰川槽谷(U形谷)指示海洋性冰川作用特征;冰川作用正差、冰川朝向、冰蚀地貌的差异,揭示积累区地形条件和水汽来源对研究区冰川发育具有重要的影响。

Zheduoshan Mountains is located in the eastern margin of the Qinghai-Tibet Plateau,in the transition zone from plateau to mountains and valleys,with well-preserved glacial landforms.It is of great significance to study the glacial landforms to reveal the coupling mechanism between the evolution of topography and paleoclimate change in the eastern margin of the Qinghai-Tibet Plateau.On the basis of field investigation,combined with Google Earth remote sensing image,The Second Glacier Inventory Dataset of China(Version 1.0),glacial landforms and its characteristic parameters are identified and calculated.A total of 189 ancient glaciers were identified,covering an area of 497 km^(2).Based on the available chronological data,the glacial landforms in the study area are mainly remains of glaciations since the last glacial maximum(LGM).The results show that the height of LGM glacier equilibrium line(ELA)is 4380 m on the west slope and 4110 m on the east slope,with a difference of 270 m,indicating that the east side of the watershed is more favorable for glacier development.The widely developed glacial lakes,glacial bedrock surface,roche moutonnée,etc.,and deep glacial trough(U-shaped Valley)indicate the characteristics of temperate(marine)glaciation;the positive glaciation amplitude,glacial valley orientation and erosion landforms reveal that the terrain conditions and water vapor sources in the accumulation area have an important impact on the development of glaciers in the study area.