神农架天鹅洞石笋76~58kaB.P.时段DO事件

DO Events During 76～58kaB.P. from a Stalagmite in Tian’e Cave, Shennongjia Area

据神农架高海拔天鹅洞一支石笋9个^230^h年龄和332组氧、碳同位素数据，建立了76～58kaB．P．Dansgaard-Oeschger（DO）事件时间序列，揭示了深海氧同位素4阶段（MIS4）东亚季风降水百年尺度变化过程。天鹅洞和葫芦洞石笋、格陵兰NGRIP冰芯δ^18O对比显示，天鹅洞记录DO18事件暖湿程度相当于深海氧同位素3阶段（MIS3）水平，其振幅类似于格陵兰冰芯δ^18O记录。起始时间上，天鹅洞记录DO18事件在710年。^230Th测年误差范围内和葫芦洞记录保持一致，并支持了NGRIP冰芯记录对应时标。在全球降温背景下，如此典型DO事件指示了强季风降水过程。70kaB．P．左右，冰芯DO19事件至少老于石笋记录约950年，远大于700年左右的^230Th测年误差，对老于该时段的冰芯时标需高分辨率地质记录进一步验证。69．09～64．64kaB．P．（DO19＇～18）期间，冰芯记录的百年尺度峰谷变化和天鹅洞石笋记录一一对应，反映了低纬热带海洋和北大西洋温盐环流之间耦合作用。

An oxygen-isotope record of a thorium-uranium-dated stalagmite from Tian＇ e Cave at Shennongjia reflects variation of the East Asian monsoon during the period from 76 to 58 kaB. P. The high-resolution （40-yr）δ^18O record display SW12, DO18 ing of ageof global s a centennial-scale variability of the monsoonal precipitation during MIS4. Comparison between stalagmite Tian＇ e Cave, stalagmite MSL, Hulu Cave and NGRIP ice core shows that moisture intensity of Tian＇e Cave event reaches that during MIS3, with an amplitude similar to the counterpart in polar record. The initiation tim- DO18 event, Tian＇s Cave is consistent with that in Hulu Cave within the dating error, and further confirmed the polar DO18 event. Such a strong peak reveals a period of strengthened summer monsoon under a decrease in temperature during MIS4. Before 70 kaB. P. , DO19 event in ice core is older than the counterpart in Asian monsoon at least by 950 years, which is far beyond ^230Th dating error of about 700 years. During 69.3 - 64.4 kaB. P. （ DO19＇-18 ）, centennial oscillations in ice core are an analogy to those of stalagmite SW12, suggesting an interaction of tropical sea and North Atlantic thermohaline.