中文摘要：

对采自川东北仙人洞的石笋XR025进行了高精度230Th定年和高分辨率氧-碳同位素分析,重建了该地区33～ 28ka B.P.高分辨率夏季风气候变化历史.结果发现,XR025清晰地记录GIS4,GIS4.1和GIS5等温暖事件以及H3这一寒冷事件,这些事件的发生时间与格陵兰冰芯和我国其他石笋记录基本一致.但XR025记录的GIS4.1事件的强度明显比GIS4事件弱,这与格陵兰冰芯和葫芦洞石笋记录一致,但与我国其他一些石笋记录存在差异.在从H3向GIS4的转化中,XR025记录了夏季风逐渐增强的过程,这与格陵兰冰芯和我国其他石笋记录均存在明显差异,但与南极温度变化相似,可能受到了南极温度变化的影响.因此,南北半球高纬度地区温度变化可能在33～28ka B.P.对我国中部地区的夏季风气候变化产生了重要影响.

英文摘要：

Stalagmite XR025,which is 115mm in length with a flat top,was sampled from.Xianren Cave （32°24′N,107°10′E） in NE Sichuan,Central China.Six precise 230Th dates indicate that XR025 developed during ca.33～28ka B.P.with an average growth rate of 23μm/a.A total of 115 sub-samples were measured for stable oxygen and carbon isotopes （δ18O and δ13C） to reconstruct high-resolution summer monsoon （SM） variations in central China during 33 ～ 28ka B.P.The XR025 δ18O record varies notably,ranging from-10.3‰ to-7.3‰ with an average of-9.1‰o,suggesting significant SM variations on millennial scale.The SM strengthening and weakening archived in XR025,which are associated with the GIS4 ～ 5 warm events and H3 cold event in northern high latitudes,respectively,are synchronous within dating errors with those documented in other speleothem records from monsoonal China.The SM strengthening associated with the secondary warm event GIS4.1,however,is apparently less intensive than that associated with the GIS4 event.This is similar to the Hulu record from East China and the NGRIP record from Greenland,but different from the Sanbao and Dashibao records from China.In addition,the transition from the weakest SM of H3 to the peak SM of GIS4 is steady,unlike the two-step transitions （one gradual strengthening followed by an abrupt strengthening） recorded by Greenland ice core and other Chinese stalagmites.Instead,it is similar to the temperature changes in Antarctic.These results suggest that temperature changes in both Northern and Southern high latitudes may have exerted significant influences on SM variations in Central China during 33 ～ 28ka B.P.