关键词: 青藏高原, 纳木错, 湖相沉积, 晚更新世, 环境演化与气候变迁

Abstract: The results of the measurement by the waterlevel instrument show that there are the lacustrine deposits from 48 to 139.2 meters and the six grade lake terraces whose heights are less than 48 meters above the lakelevel along the coasts of the Nam Co Lake. According to the measurement of geological sections, strata sequence and lithology, isotopic dating of the lacustrine and lakeshore deposits, the strata of the lacustrine deposits has been divided into one group and two formations. The studies of the salt sediments, pH value, geochemistry, clay minerals, ostracoda and sporopollen analysis show that the lakeshore deposits recorded the information of the environmental evolution and climate changes from 116 ka B.P. The dada shows that from 116 ka B.P. the best warm and humid climate occurred in Holocene, but from 90.1 to 86.5 ka B.P. the climate is relative warmer, temperature was equal or slightly higher than that of the present, belongs to warm and humid or slightly dry climate; from 36.0 to 35.0 ka B.P. air temperature and humidity is slightly high or higher than that of the present. The study results show that the environment have experienced many times of coldwarm changes and dryhumid changes within the total changing trend from cold to warm gradually since the Late Pleistocene.

Key words: Qinghai-Tibet plateau, Nam Co, lacustrine deposits, Late Pleistocene, environmental evolution,  climatic change