稻城古冰帽第四纪冰川地貌数字化研究

Digital study of Quaternary glacial geomorphology in paleo-Daocheng ice cap

位于青藏高原东南部的稻城古冰帽,在第四纪时期曾发生了多次冰期并保存了丰富的古冰川遗迹,是研究第四纪冰川地貌类型特征的理想区域。目前,已有学者对冰川地貌类型划分和冰川地貌制图做了相关研究,但是古冰川地貌在空间分布特征及其量化程度有待于进一步细化。因此,本文基于Google Earth Pro遥感影像和数字高程模型(DEM),运用目视解译和野外考察相结合的方法对典型冰川地貌进行定量分析并绘制了稻城古冰帽(约3600 km2)的第四纪冰川地貌图。本文识别了该区冰川地貌中的冰川湖、冰川谷、羊背岩和冰碛垄等四种类型,初步统计了约1096个冰川湖、370条冰川谷、41个羊背岩及1268列冰碛垄;空间分布上,冰川湖和羊背岩主要分布在海子山夷平面上,冰川谷以古冰帽边缘区发育为主,冰碛垄则主要形成于海子山夷平面上和东、西两侧的山谷里。本研究可为第四纪冰期规模估算、古气候重建提供基础数据,也为当地的旅游规划和自然资源调查提供一定的参考。

The paleo-Daocheng ice cap is located on the hilly plateau of Shaluli Mountains in the northeast of Hengduan Mountains.Quaternary extensively repeated glaciers and glacial landforms are well preserved.It is an ideal area to study the characteristics of Quaternary glacial landforms.Scholars have conducted research on the classification of glacial geomorphologic types and glacial geomorphologic mapping.However,the spatial distri⁃bution characteristics and quantification of paleoglacial landforms need to be further refined.To address this,this study used a combination of visual interpretation and field investigation based on Google Earth Pro remote sensing images and digital elevation model(DEM).Firstly,based on visual interpretation,the target object and its distribution feature information on the image are identified through the shape,position,color tone and other characteristics of the object.Secondly,combined with field investigation,one-site verification of some glacial landforms was carried out.Finally,Quaternary glacial geomorphologic map of the paleo-Daocheng ice cap(about 3600 km2)was quantitatively analyzed and plotted in ArcGIS 10.5.This study identified and mapped four glacial geomorphological types,including glacial lake,glacial valley,roche moutonnees and glacial mo⁃raine.The paleo-Daocheng ice cap is mainly composed of the ice cap type glacial landform on the plane of Haizi Mountains and the valley glacier landform on the margin.Among them,there are 1096 glacial lakes,mainly distributed on the plane of Haizi Mountains.The terrain is undulating,with the glacier eroding the plane in the form of ice caps to creat rock basins.There are about 370 glacial valleys,mainly distributed at the north and south ends of the paleo-Daocheng ice cap.There are strong tectonic faults and water erosion in the marginal ar⁃ea,which promote the development of glacial valley.There are 41 roche moutonnees,which were developed in the central area of the paleo-Daocheng ice cap.The bedrock in the area is exposed and the glacier is mostly erod⁃ed,resulting in the formation of roche moutonnees.There are about 1268 rows of glacial moraine,mainly dis⁃tributed at the end of the glacial valley on the east and west sides,the foothills and the plane of the Haizi Moun⁃tains.This study provides basic data for reconstructing paleo-glacier extents and examining climate change and a certain reference for local tourism planning and natural resource investigation.