Late Glacial And Holocene Palaeovegetation And Palaeoenvironment Changes In The Gonghe Basin, Tibet Plateau

Gonghe Basin is located on the northeast edge of Tibet Plateau and the northwest margin of modern summer monsoon where is the transitional boundary of arid and semiarid regions of China. Due to its unique geographical location and fragile ecological system, the basin is a suitable place for the research of regional climate in response to the global climate change.A 40.92m long core (DLH) was drilled in a terminal lake—Dalianhai Lake in Gonghe Basin. The preliminary chronology of which was established by AMS C-14 dating on several plant remains from the sediment. In combination with Cs-137 timescale of former study, the carbon reservoir effect of 380 yrs was deducted to give the final credible chronology of Dalianhai Lake since the late glacial. On the basis of this reliable chronology, the evolutionary history of palaeovegetation and palaeoenvironment in Gonghe basin during the late glacial and Holocene was reconstructed mainly by pollen analysis (200 samples with 70-yr resolution) and other proxies such as grain size (1025 samples of 15-yr resolution) and carbonate content (1029 samples with resolution of 15 yrs) as complement as well.The result of pollen analysis shows there are eight pollen zones can be partitioned in the whole pollen assemblages, and each zone is mainly characterized with the growth and decline of arbor or herbaceous pollen percentage. The arbor pollen percentages are relatively high in zone I, IV, V and VI, namely 14.6-12.3 Cal ka BP and 8.9-3.4 Cal ka BP, dominated by conifer pollen such as Picea and Pinus, but meanwhile the herbaceous and shrub pollen percentage are not very low. In Zone II, III, VII and VIII, around 12.3-8.9 Cal ka BP and 3.4-0 Cal ka BP, the...