Geomorphological history of the basin and the origin of Qinghai Lake

Qinghai Lake, situated in the northeastern part of Tibet-Qinghai Plateau at latitude 3TN and longitude 100'E, is a closed saline lake of 4,484 km2 on area in the interior China. The main mountain in the basin is given attention to the highest one of 5,174 m in South Sule Mountains of northwestern side where there are found in the only existence of glacier and the lower limit of glacier exists to the altitude of 4,700 m. But, in the last glaciation, it was judged that the mountain glacier had reached to the altitude of 3,800 m. In the lake basin, there are found remarkably the three lacustrine terraces that the relative height from the present lake-level are: 10~15 m of the lowest one (1,880 yr. B.P.), 25~50 m of the middle one (4,830 yr. B.P.) and 60~80 m of the highest one (about 8,000 yr. B.P.). The lacustrine sediment cores to the 60 m depth were obtained by the drilling near the shore of Erhai Lake in the estuary of Daotang River inflowed from the eastern basin. The sediments are given with the 14C age of 7,300 yr. B.P. for 10 m depth and 30,700 yr. B.P. for 30 m depth