天山乌鲁木齐河源1号冰川冰蚀基岩面微形态研究

Subglacial Process Indicated by Microstructures on Ice-bedrock Surface in Glacier No.1 at the Headwater of the rümqi River,Tianshan

通过对天山乌鲁木齐河源冰川底床基岩与沉淀物显微结构构造分析,对大陆性山岳冰川冰下过程的认识更加深入.沉积物微观结构和构造特性显示冰川底部存在较大的挤压应力作用,由显微滞碛等现象来看,压应力在微观上的空间分布很不均匀.沉淀物中块体碎裂和基岩上冰成裂隙反映,冰川底部冰体对基岩面有巨大的剪切应力作用.滑塌构造说明,冰川底部在微小的区域内压力分布不均匀,局部有重力作用过程存在.沉淀物中块体断裂和同生变形构造的存在说明沉淀物的形成过程为先期沉淀、后期受压.通过对冰川底部各种动力作用特征的阐述及沉淀物结构、构造的成因及特性的总结,认为大陆性山谷冰川底部冰岩界面处存在水膜,且冰川运动亦有滑动性.

In the past years, a lot of research works have been done on the erosion, transportation and deposition of glaciers. Through these researches, the distribution of glacial deposits and glaciations on large scales has been becoming clearer. But less interaction at ice-rock interface has been reported, especially from a micro-view. In this paper, some micro-structures of thinlayer deposits on the roche moutonee surface are described mainly, such as convolute bedding, slump structure, micro-fracture, filling structure and so on. After extracting and analyzing some of the structure traces, the interaction at the bottom of a glacier can be recognized, and much useful information can be gathered. From this information, it can be verified from a micro-view that compress- ing friction, shearing and gravitation sliding exist at the ice-rock interface. In addition, it is demonstrated that basal sliding and water film exist at the ice-rock interface on the bottom of a continental glacier.