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 2 4 5 2 0kaB P 至 14 7 90kaB P 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 2 4 2 5± 6 4kaB P (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 9kaB 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2 4 5 2 0～ 14 7 90kaB P 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) 2 4 5 2～ 2 4 2 6kaB P ,相当于深海岩芯氧同位素标准曲线阶段 8的末期 ;(2 ) 2 4 2 5～ 192 6kaB P ,相当于深海岩芯氧同位素标准曲线时段 7;(3) 192 6～ 14 7 9kaB P 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 2 4 5 2～ 14 7 9kaB P 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?
The time sequence of palaeoclimatic change from 245.20ka B.P. to 147.90ka B.P. has been established by the dating ages of the high precision TIMS-U 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 B.P.(corresponding to the deep-sea core oxygen isotope stage 6 and 7),242.5±6.4 ka B.P.(corresponding to the deep-sea core oxygen isotope stage 7 and stage8) respectively,which is gotten by using TIMS-U 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 B.P. and 147.9 ka B.P. can be divided into three stages:(1)the period from 245.20 ka B.P. to 242.6 ka B.P. 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 B.P. to 192.6 ka B.P. corresponding to stage 7 of the SPECMAP curve;(3)the penultimate glacial period from 192.6 ka B.P to 147.9 ka B.P. 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 B.P. to 147.9 ka B.P. 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,CaCO 3 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 CaCO 3 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.
出处
《古地理学报》
CAS
CSCD
2004年第1期57-68,共12页
Journal of Palaeogeography：Chinese Edition
基金
袁道先院士IGCP -4 48国际对比项目
科技部攀登特别资助项目"全球岩溶生态系统对比" (编号 :2 0 0 0 -0 2 6)
国家自然科学基金 (批准号 40 2 3 10 0 8)资助
关键词
碳
氧
同位素记录
古气候
石笋
Stalagmite,TIMS-U series age,C and O isotope records,palaeoclimatic reconstruction,Shuinan Cave,Guilin
