北京大学学报自然科学版 ›› 2020, Vol. 56 ›› Issue (6): 1065-1072.DOI: 10.13209/j.0479-8023.2020.075

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西藏普兰地区第四纪以来冰锯作用研究

郭浩, 刘耕年   

  1. 北京大学城市与环境学院, 北京 100871
  • 收稿日期:2019-10-10 修回日期:2020-06-24 出版日期:2020-11-20 发布日期:2020-11-20
  • 通讯作者: 刘耕年, E-mail: liugn(at)pku.edu.cn
  • 基金资助:
    国家自然科学基金(41771005)资助

Effect of Glacial Buzzsaw during Quaternary in Puland, Tibet

GUO Hao, LIU Gengnian   

  1. College of Urban and Environmental Sciences, Peking University, Beijing 100871
  • Received:2019-10-10 Revised:2020-06-24 Online:2020-11-20 Published:2020-11-20
  • Contact: LIU Gengnian, E-mail: liugn(at)pku.edu.cn

摘要:

为了验证西藏普兰地区冰川作用对地形演化的影响, 选取纳木那尼峰、喜马拉雅山和冈底斯山3个区域, 利用数字高程模型(DEM)数据和遥感影像, 对现代冰川与末次冰盛期(LGM)古冰川平衡线高度(ELA)、冰川作用区坡度与高程的关系以及冰川分布的高程频谱进行计算和分析。结果显示, 研究区内冰川剥蚀作用显著、坡度降低最明显的地带位于LGM古冰川平衡线附近, 并在一定程度上限制山脉的高度。根据冰川地貌特征参数和前人研究结果, 认为气候是影响冰锯作用的主要因素。冰期时, 研究区内西风急流南移, 风速增强, 降水量增多, 为冰川发育创造良好条件, 冰锯作用也增强。对于构造抬升强烈的山脉(如纳木那尼峰), 虽然冰锯作用得到加强, 但是构造抬升增加的山脉高度不会完全被冰锯作用抵消。

关键词: 冰锯, 平衡线高度(ELA), 海拔, 坡度, 构造抬升, 气候

Abstract:

In order to verify the effect of glacial buzzsaw on the evolution of landform in Pulan region of Tibet, three areas of Gurla Mandhata (Naimon’anyi), Himalayas and Gangdese are selected. Based on digital elevation model (DEM) data, remote sensing images, the equilibrium line altitude (ELA) of modern glacier and last glacial maximum (LGM) glacier, the relationship between slope and elevation and the elevation distribution are calculated and analyzed. We conclude that the areas with significant glacier erosion and the most obvious slope reduction are located in the area near LGM glacial equilibrium line and the heights of the mountains are limited in some degree. Based on the glacial landform characteristics and previous investigations, we believe that climate is the most important factor influencing the effectiveness of glacial buzzsaw. During glacial periods, the westerly jets moved southward, wind speed and precipitation increased, and the precipitation increased, resulting in favorable conditions for the development of glaciers and the effect of glacial buzzsaw. For mountains with strong tectonic uplift, such as Gurla Mandhata in the study area, although the effect of glacial buzzsaw is strengthened, the height increase caused by tectonic uplift is not completely offset by glacial buzzsaw.

Key words: glacial buzzsaw, equilibrium line altitude (ELA), elevation, slope, tectonic uplift, climate