Abstract:

The time sequence of palaeoclimatic change from 245.20ka BP to 147.90ka BP has been established by the dating ages of the high precision TIMSU series and the analysis of the oxygen isotopes from the stalagmites of Shuinan Cave in Guilin area  The paper also confirms that the boundary ages between stage C and stage B and those between stage B and stage A are 1926±3.9 ka BP(corresponding to the deep sea core oxygen isotope stage 6 and 7),242.5±6.4 ka BP(corresponding to the deep  sea core oxygen isotope stage 7 and stage8) respectively,which is gotten by using TIMSU series dating age at 86.5 cm on the stalagmite section and depositional cycles of the stalagmite section and the sudden change characteristics The result indicates that the paleoclimate (or paleomonsoon) change reflected by the cold and warm events of the stalagmite records during 245.20 ka BP and 147.9 ka BP  can be divided into three stages:(1)the period from 245.20 ka BP to 242.6 ka BP corresponding to the last stage of the deepsea core oxygen isotope(SPECMAP curve) stage 8 ; (2) the penultimate interglacial period from 242.5 ka BP to 192.6 ka BP corresponding to stage 7 of the SPECMAP curve;(3)the penultimate glacial period from 192.6 ka BP to 147.9 ka BP corresponding to stage 6 of the SPECMAP curveThe records of TIMSU series dating ages and stable isotopes from the stalagmite reveals that the evolution history of the East Asian monsoon from 242.6 ka BPto 147.9 ka BP occurred in Guilin area corresponded well with the paleoclimate and paleomosoon changes revealed by the records of the deepsea core oxygen isotope stage 6 and stage 7, sporepollen combination,CaCO3 content from the deepsea core records and loess and paleosol from the North China,and by sea level rise and fall,soil forming,complete iron accumulation degree of loess and paleosol, magnetization rate change and the original crumb CaCO3  content and eluviation intension from the North China and so on These characteristics show that the paleoclimate evolution since the late stage of the Middle Pleistocene Epoch in Guilin area not only has the global characteristics but also has the strong regional characteristics

摘要：

通过对桂林水南洞石笋进行高精度的热电离质谱(TIMS－U)测年和碳氧同位素分析，建立了桂林地区245.20 ka BP至147.90 ka BP间的古气候变化时间序列，确定了石笋记录的时段B与时段C分界的年龄为242.5±6.4 ka BP(相当于深海岩芯氧同位素标准曲线时段7与时段8分界的年龄)、时段A与时段B分界的年龄为 192.6±3.9 ka BP(相当于深海岩芯氧同位素标准曲线时段6与时段7分界的年龄)。桂林地区245.20～147.90 ka BP石笋记录的冷暖事件所反映出的古气候变化，大致可分为3个气候变化阶段:(1) 245.2～242.6 ka BP, 相当于深海岩芯氧同位素标准曲线阶段8的末期；(2) 242.5～192.6 ka BP，相当于深海岩芯氧同位素标准曲线时段7；(3)192.6～147.9 ka BP间的倒数第2次冰期, 相当于深海岩芯氧同位素标准曲线时段6的早中期。石笋的TIMS－U测年和碳氧同位素记录揭示，桂林地区245.2～147.9 ka BP的古气候演变历史与深海岩芯时段8末期、时段7和时段6的氧同位素，深海岩芯中记录的孢子花粉组合、CaCO3含量、海平面的升降变化以及与中国北方黄土、古土壤中记录的孢子花粉组合、成壤程度、全铁富集程度、磁化率变化、原生碎屑CaCO3含量和淋溶强度等所揭示的古气候和古季风变化具有极好的对应关系，表明桂林地区中更新世晚期以来的古气候演变既有全球性特征，又有着强烈的区域性特征。