Paleodrainage evolution since 60 kaB.P. by radar remote sensing in north- eastern Ejin banner, Inner Mongolia of China

摘要

Based on radar remote sensing and sediment facies analyzing, this paper studies the features of environmental evolution of North-eastern Ejin Banner since 60 Ka BP(Before Present). The conclusions are listed as follows: (1) The evolution of Gaxunnur Lake, Sugunur Lake, Tian'e Lake is dominated by faults and regional climate; (2) By analyzing deposit of old Juyanze Lake, it is a large outlet lake about 50Ka BP. Just about 50Ka BP, there was a rapid decline of temperature in the Northwestern of China. The events caused those lakes shrinkage. (3) By fault activity arising uplift in the north of old Juyan Lake and depression in the south, the lake's water flowed out from north to south at around 35Ka BP, which is reversed to the former flow direction. So, old Juyanze fluvial fan was formed. At the same time, Juyan Lake separated from Sugunur lake and Wentugunr old channel was abandoned. (4) Near 2000 years, Ruoshui River is a wandering river. Due to intense influence of human activities, the oasis ecosystem is rapidly degenerated in recently 15 years.