Paleoclimatic evolution indicated by major geochemical elements from aeolian sediments on the east of Qinghai Lake

摘要

As the largest inland lake of China, along with its unique landscape and geographical location, Qinghai Lake has got much atten- tion of the scientists for a long time. The precursors have done substantive researches by using the lake sediment, which deepen our understanding of the climate changes in this region. Although sand dunes and loess sediment are widely distributed around the lake, so far the researches on geochemical elements from aeolian sediment have been less reported. In this paper, we selected a typical aeolian profile on the east of Qinghai Lake. Based on systematic sampling and analysis of seven major geochemical elements, combined with OSL dating and previous researches, this paper discusses climate changes in the Qinghai Lake area since 12.5 ka B.P.. Our conclusions are: (1) Before 12.5 ka B.P., the climate in this region was dry, cold, and accompanied by strong wind-sand activities. (2) During 12.5-11.9 ka B.P., the climate became warm and wet. However, there was an abrupt climate cooling event during 12.2-11.9 ka B.P., which likely corresponded to the Younger Dryas event. (3) During 11.9-8.0 ka B.P., the climate fluctuated greatly and frequently from warm to cold, and three cooling events occurred. (4) During 8.0-2.6 ka B.P., the climate was warm and humid. (5) Since 2.6 ka B.P., similar to the modern climate, the climate was mainly dry and cold.