HR: 1340h
AN: U13B-1143    [Abstracts]
TI: A 60,000-yr Record of Climate From Lake Qinghai: A Comparison With a Proxy Record From the South China Sea
AU: * Yu, J
EM: junqyu@isl.ac.cn
AF: Institute of Salt Lake Studies, Chinese Academy of Sciences, 18 Xinning Road, Xining, 810008, China
AU: Zhang, L
EM: lisazhang05@yahoo.com.cn
AF: Institute of Salt Lake Studies, Chinese Academy of Sciences, 18 Xinning Road, Xining, 810008, China
AU: Wang, C
EM: wangchunning05@163.com
AF: Institute of Salt Lake Studies, Chinese Academy of Sciences, 18 Xinning Road, Xining, 810008, China
AB: Lake Qinghai is a closed-basin lake and the largest waterbody in China, located at the outer margin of the Asian summer monsoon today. Past fluctuations of the lake level were subject to the changes of the monsoon circulation. The reconstruction of lake level and climate over the past 60 ka is based on data from a multi-proxy investigation on two piston cores and a 26 m drill core recovered from the central subbasins of the lake, and on subbottom sediment structures as revealed by high-resolution seismic profiles of more than 300 km. The results indicate that both lake size and temperature during the Marine Isotope Stage 3 did not exceed those of the Holocene, and that the paleo-lake during the LGM separated into smaller lakes and windblown loess-like sediments deposited, indicating an extremely cold and arid climate. Seasonal catchment inflow increased at 11.6-10.7 ka though the lake was less than 6 m deep. The arid Younger Dryas equivalent at 10.7-10 ka was followed by an abrupt onset of the warm early-Holocene climate but the effective moisture at 10-8 ka was much lower than that of today. A permanent expansion of Lake Qinghai occurred at 10 ka and the lake began to increase towards the present-day dimension from about 8 ka. This reflects a stepwise enhancement of summer rainfall on the NE Tibet-Qinghai Plateau. The G. rubber δ¹⁸O record from a northern SCS core suggested that the main pattern of climate change since the MIS 3 is consistent with that documented in the Greenland GISP2 δ¹⁸O record. The SCS during the MIS 3 was overall under the conditions of a strong winter monsoon and weak summer monsoon precipitation, as also indicated by low fluvial clay content and high modal grain size. The proxy record clearly indicates deteriorated conditions during the LGM. The correlation of the SCS record with Lake Qinghai suggests that the paleoenvironmental conditions of the western Pacific marginal seas and the WPWP had a substantial impact of moisture availability on the outer margin of the Asian summer monsoon, which determined that the strength of the summer monsoon during the MIS 3 was weaker than the Holocene. During the LGM, a combined impact of southward-shifted polar front and an about 100 m decrease of the WP marginal sea levels resulted in a further increase of aridity on the NE Plateau.
DE: 0746 Lakes (9345)
DE: 1605 Abrupt/rapid climate change (4901, 8408)
DE: 1616 Climate variability (1635, 3305, 3309, 4215, 4513)
DE: 4914 Continental climate records
SC: Union [U]
MN: 2007 Fall Meeting