摘要
Wanxiang Cave is sensitive to climate change due to its special geographic location,located at the transition of Tibet plateau and Loess plateau.A 10-year resolution oxygen isotope record of stalagmite from the Wanxiang Cave,based on 6 precise 230Th dates and 616 oxygen isotopic measurements provides a detailed history of the Asian Monsoon from 28.3 to 23.0 ka B.P..A high-resolution oxygen isotopic record reveals decadal-centural oscillations in air temperature in the East Asian monsoon climate area during the early time of marine isotope stadial 2(MIS2).The most conspicuous feature in the oxygen isotopic record in the period is the particularly cold event synchronized with the penultimate Heinrich event(H2)in the northern Atlantic deep-sea records.This particular cold event,beginning at 24.6 ka B.P.,δ18O record demonstrates that the event lasted 1 200 years with gradually cooling,which is different from δ18O record from Hulu Cave and Tiané Cave—a gradually cooling tendency after the remarkable cooling down.However,the δ18O record from Wanxiang Cave matches well with 33°N insolation and δ18O record from Jintanwan,Hunan Province;The cooling event recorded in Wanxiang Cave is also consistent with δ18O record in GRIP.We maintain that this unique pattern of event recorded in the stalagmite δ18O might be controlled by various factors including solar radiation,expansion of ice raft debrise in the northern Atlantic and sea surface temperature.The particular location of the Wanxiang Cave makes the stalagmite δ18O easily affected by Asian winter monsoon and westly circulation correlated with Polar climate.