The Climate Change Since The Last Glacial Maximum Reflected By Lake Ostracods Of Taro Co

The Tibet Plateau is known as the"third pole"of the earth.Affected by the Indian summer monsoon,East Asian summer monsoon and westerly circulation.The huage influence of plateau uplift on the formation of northern hemisphere and even the global climate in Tibet Plateau region.Since the Last Glacial Maximum(LGM),it has experienced the LGM period of cold and drought,the last deglaciation period of rapid climate fluctuation and a warming Holocene.Previous studies have shown that the climate change of the Tibetan Plateau since the last glacial maximum is significantly affected by the Asian monsoon and westerly circulation,but the influence degree and advance and retreat time of these two circulation systems in different areas of the Tibetan Plateau are still unclear.Taro Co in the southwest of Tibet Plateau under the combined action by the Asian monsoon and westerly circulation,and its climate change has obvious regional advantages.Studying the climate change history of this region is helpful to understand the response process of regional climate to global change and the interaction between Asian monsoon and westerly system in this region,Although some achievements have been made in the study of climate and environmental change in the southwest of the Tibet Plateau in the past,there is still a lack of long-time scale climate records.Therefore,this paper studies the ostracoda genus and species combination characteristics of the 11.05m long core TR14 of Taro Co,and combined with the shell?¹⁸O??¹³C and the lake water depth reconstructed by ostracod water depth conversion function to restore the lake hydrological process and climate change history since the last glacial maximum of Taro Co.Get the following understanding:1.A total of 6 genera and 6 species of ostracods were found and identified in TR14borehole of Taro Co,which are leucocythella sinensis?limnocythere inopinata?leucuocythere dorsotuberosa?Candona xizangensis?Fabaeformiscandona gyirongensis?Ilyocypris sp..2.Last Glacial Maximum:23.67?19.95 cal ka BP Taro Co climate is cold and dry,and tends to change to warm and dry in the late stage.The lake has medium water depth and certain salinity.The last deglaciation period:19.95?16.41 cal ka BP,the climate in the lake area is warm and dry,the water depth of the lake decreases,and the salinity continues to increase;From 16.41 to 13.28 cal ka BP lake area experienced cold and wet H1 event,and the lake surface decreased slightly;13.28?12.53 cal ka BP lake area is warming,corresponding to the B/A warm period;The climate cooling event occurred in 12.53?12.16 cal ka BP,which is the embodiment of YD event in Taro Co.Holocene:12.16?9.88 cal ka BP,warm and humid climate,rising lake water surface and desalination of water body;9.88?3.97 cal ka BP,the lake water level is high and the lake water overflows;3.97?0 cal ka BP,the depth of the lake is large,the water body of the lake is desalinated,and the salinity is low.The climate of the lake area is warm and humid,and gradually changes to warm and dry.3.Compared with other records,it is found that the climate and environment change in Taro Co basin since the Last Glacial Maximum is mainly affected by solar radiation.During the period of 23.67?19.95 cal ka BP,the solar radiation was at a low value,the monsoon circulation was weak,and the lake area was mainly controlled by the westerly circulation.During the last deglaciation,the westerly circulation still affected the Taro Co basin,and the weak Asian monsoon and weak westerly circulation may exist at the same time.During the period of 19.95?16.41 cal ka BP,the climate in the lake area became warmer with the increase of solar radiation,but the westerly circulation still controlled the lake area and the climate was warm and dry;During the H1 event of 16.41?13.28 cal ka BP and the YD event of 12.53?12.16 cal ka BP,the climate and environment change in Taro Co basin is dominated by the westerly circulation,the Asian monsoon may be strengthened,and the degree of humidity in the lake area has increased;During the B/A warm period between 13.28?12.53 cal ka BP,the Asian monsoon strengthened,affected Taro Co area,and the climate in the lake area became warmer.At 12.16?0 cal ka BP after the YD event,driven by strong solar radiation,the monsoon circulation increased rapidly and reached Taro Co area.The climate in the lake area was warm and humid in the early and middle Holocene:In the late Holocene,affected by the reduction of solar radiation,the monsoon circulation weakened and the humidity in the lake area decreased.