THE MID-HOLOCENE CLIMATE VARIATION INFERRED FROM A DATED STALAGMITE RECORD FROM WANGJIAWEI CAVE, NORTHEAST CHINA

Presented in this paper are the oxygen stable isotope records of the stalagmite dated with 230Th-dating method for Wangjiawei Cave in Liaoning Province,northeastern China.The records provided a clue to the history of Asian summer monsoon for the period of 10.5~5.0 kaBP.There are a series of abrupt and rapid shifts superimposed on a gradually increasing trend,indicating that the East Asian monsoon was unstable during the early Holocene.A comparison of our records to precisely dated contemporaneous stalagmite records from other caves shows that the Wanjiawan record resembles other Holocene speleothem records from subtropical locations.All of these δ18O profiles follow insolation changes,further supporting the idea that insolation is the primary factor inffuencing the Asian summer monsoon.However,a peak monsoon intensity during the early Holocene commenced as early as ~10.5 kaBP in northern China,for example in Wangjiawei and Nuanhe Caves,while this shift appeared 1 000 years later,about ~9 kaBP in Sanbao Cave and Dongge Cave at lower latitudes.It suggests an asynchronous change in summer monsoon precipitation in East Asia during the early Holocene,and the response of the East Asian summer monsoon precipitation to regional atmospheric circulations varied from the south to north due to monsoon intensity changes,resulting from the complex geographical configuration.The spectral analysis of δ18O time series shows cycles around 225a and 91a which are similar with the tree ring cycles of 208a and 88a by Δ14C isotopic data,indicating that solar changes may be,at least partially,responsible for changes in the intensity of the East Asian Monsoon on the centennial time scale during the early Holocene.