MIS7 High-resolution Luoshuidong Stalagmite Record Of East Asian Summer Monsoon Evolution

Stalagmites plays an important role in paleoclimate research because of the high resolution and precise dating.We can predict the development of the global climate and direction of the environmental evolution by reconstructing the past climate trends with stalagmites.The penultimate interglacial climate has always been the focus of paleoclimate research,especially the Holocene and the last interglacial climate study.However the study of the older interglacial period is not sufficient due to the dating accuracy and samples shortage.We can get the better analysis in Holocene climate and reference in future climate prediction by exploring the evolution of the penultimate interglacial climate.Based on 15 U/Th dates and 961 stable oxygen isotope ratios(?¹⁸O)of the stalagmite?No.LS42?,we reconstructs the high resolution record of East Asian summer monsoon from 229.42?196.14 ka B.P.with the average resolution about 35 a.The time series of the?¹⁸O in LS42 is agree well with the summer insolation at 65°N,directly follow the changes in North Hemisphere summer insolation on orbital timescales.Otherwise the similar series of?¹⁸O in Asian monsoon area indicates that controlled by the same climatic factors and it can reflect the climate change.Here we present an EAM records LS42,together with previous records LS30 and LS26,all from the Luo Shui cave,and characterize the complete Chinese interstadial?CIS?series for the penultimate interglacial–glacial cycles.There are some striking similarities among the Luo Shui and San Bao records in MIS7,indicating that CIS events are Asian summer monsoon proxy during the two interglacial periods.The B23 event and the 202-200 ka B.P.event lag behind the changes in summer insolation about5ka,which have great correlation with the changes of the North Atlantic sea surface temperature records and the European pollen records.Therefore,the AMOC and the Subpolar Westerlies may have significant influence in transmit the polar climate signal to mid-low latitudes,resulting the abnormal difference between the summer insolation and?¹⁸O records.Stalagmites?¹³C value mainly reflects the soil CO₂production rate.The aboveground vegetation biomass changes with the monsoon intensity,which in turn affects the Stalagmites?¹³C value.There is a good cmillennial scale correlation between the?¹³C and?¹⁸O curves of LS42,showing a significant peak corresponding features,showing the the two have a common drive mechanism on the millennium-centennial scale.The gray scale of LS42 may be related to the temperature change caused by the insolation.There have a increasing vegetation biomass and micro-organism activity with a warm and humid environment,the soil organism is largely decomposed,then the carbon content in soil water is reduced,while the?¹³C negative bias,in this case the particles of soil organic matter content increased,the gray scale also decreases;and vice versa.Sr/Ca with?¹³C still have a strong anticorrelation between them,and the Sr/Ca change in stalagmite can provide an effective supplement for paleoclimate reconstruction.When the study area has a lager precipitatio,the vadose water flow rate is increased,the residence time in the bedrock is shortened,the CO₂in soil biological and rainwater do not reach the isotopic equilibrium,and then?¹³C positive.At this time,the bedrock dissolved less,and Sr has a less priority leaching empriment over Ca,then with a lower Sr/Ca values for stalagmites;and vice versa.