唐古拉山西段格拉丹东峰末次冰期以来冰川演化序列与冰川变化研究

Geladandong Peak is located in the western Tanggula Mountains, and at the edge of Westlies and Asian Monsoon. Qaternary glacier relics were well-preserved in this region. But, only a few research on Quaternary glaciers was carried out in the middle Tanggula Mountains. So far, there is still no systematic research on glacial chronology in the Geladandong Peak. Meanwhile, the research on area, volume and equilibrium line altitude of paleoglaciers are absent. This project intends to investigate and measure the typical glacier landforms of the Geladandong Peak and to confirm the evolution sequence and scales of the paleoglaciers since the Last Glacial; We will utilize the Be-10 dating method to establish the absolute chronological sequence of the paleoglaciers since the Last Glacial, especially since the Holocene. We will also reconstruct the length, area, thickness, volume and equilibrium line altitude of paleoglaciers of each glacial stage, and then reconstruct the glacial paleoclimate information in this region by modelling. Therefore, comparing with the glacier evolution characteristics of the central and southern plateau, namely Lhagoi Kangri Range and Nyainqentanglha Mountain, which affected by the Indian monsoon, and discuss the differences in glaciers responding to climate change in different climate regions. This project will provide powerful evidences to understand the evolution of the paleoglaciers on the Tibetan Plateau, since the Last Glacial, and its response to climate change.

格拉丹东峰位于唐古拉山脉的西段，属于盛行西风与季风共同作用的过渡地带边缘，第四纪冰川遗迹丰富。目前，仅在唐古拉山中段有少量的第四纪冰川研究，格拉丹东峰尚未开展系统的冰川年代学研究，同时古冰川面积、体积、冰川平衡线等的研究也很缺乏。本申请拟对格拉丹东峰地区典型冰川的古冰川地貌进行野外调查和测量，查明该地区末次冰期以来的冰川期次和规模；利用Be-10暴露测年方法建立该区末次冰期，尤其是全新世以来的冰期绝对年代序列；并通过模型定量化恢复冰期时的冰川长度、面积、厚度、体积和平衡线高度等参数，重建该地区的冰期古气候信息。进而，与受印度季风影响的高原中南部（拉轨岗日山、念青唐古拉山）冰川演化特征比较，探讨不同气候区冰川对气候变化的响应差异，为认识青藏高原末次冰期以来冰川演化及其气候变化响应机制提供有力的证据。

唐古拉山是夏季季风环流进入高原腹地的一道屏障，西段格拉丹东峰地区受夏季风影响较弱。对唐古拉山西段岗陇加玛冰川的野外调查发现该区域冰碛垄相对完好，至少对应4-5次冰期。基于5组冰碛物宇生核素Be-10测年结果，获得了MIS5b（109.01ka）,MIS4(60.94-76.72ka)，MIS3(40.28-59.43ka),新冰期(0.8-1.43ka)和小冰期(0.22-0.49ka)的年代序列。岗陇加玛冰川谷中最老的冰碛物可能形成于MIS5b时期，其冰川规模可能小于MIS4和MIS3时期，MIS4或MIS3阶段的冰川越过MIS5b时期的冰碛垄到达山麓出沟口处。. 基于地貌分析和年代学结果，恢复了MIS5b以来古冰川的变化范围，利用PaleoIce模拟各次冰川的厚度和冰面高程分布，进而获得各时期的面积和体积。模拟计算结果显示：现代冰川平均厚度为67.71m,体积为1.04±0.21 km3。MIS3, MIS5b，新冰期，小冰期冰川厚度分别为134m,123.98m，117.35m和107.71m,冰川面积扩张指数分别为1.64，1.49，1.33，1.13，体积扩张指数分别为3.24，2.73，2.30，1.79。与青藏高原南部的拉轨岗日山和念青唐古拉山西段相比，同一时期唐古拉山西段冰川变化（面积，体积等）相对较小，冰川的物质平衡线变化值也小于其他两个区域。这可能是由于拉轨岗日山和念青唐古拉山西段受印度季风影响较大，冰川对气候变化的响应可能更敏感，而唐古拉山位于高原腹地，受季风影响小，气候变化幅度小，因此冰川变化幅度也小。此外，岗陇加玛冰川为极大陆型冰川，冰川谷底平坦宽阔，冰川运动速度缓慢，也可能造成冰川变化以增厚为主，扩张范围较小。结合已有古气候信息，降水增加可能是该区域冰川前进的主要原因。