贵州荔波42.0kaB.P.~65.0kaB.P.气候变化的石笋记录

The Records of Paleo-climate Change from a Stalagmite of Dongge Cave in the Preiod of 42.0 ka B.P.to 65.0 ka B.P.in Libo

关键词:  石笋  碳  氧同位素  TIMS年龄  气候记录

Key words:  stalagmite  carbon  oxygen isotope  dating ages of TIMS-U series  climate record

摘要:

对贵州荔波董哥洞D42石笋进行TIMS-U测年和碳、氧同位素分析,建立末次冰期42.0kaB.P.~65.0kaB.P.的古气候变化时间序列。研究结果表明,荔波地区在65.0ka B.P.~42.0ka B.P.石笋记录的冷暖事件所反映出的季风气候变化,大致可分为3个气候阶段:65.0ka B.P.~60.6ka B.P.相当于海洋氧同位素MIS4晚期,反映本阶段东亚冬季风强盛,气温降低,表现为干旱寒冷的气候环境;60.6kaB.P.~48.4ka B.P.相当于海洋氧同位素MIS3早期,反映东亚夏季风相对增强,气温升高,有效降水相对较少,表现为温暖半干旱的气候环境;48.4ka B.P.~42.0ka B.P.相当于海洋氧同位素MIS3中期,显示东亚夏季风由强变弱,东亚冬季风相对增强,表现为干旱冷凉的气候环境。石笋记录揭示的2次寒冷事件在各类沉积物中均有记录,反映为全球变化的气候事件,相当于北大西洋沉积物中的Heinrich5和Heinrich6冷事件,可以进行全球对比,显示荔波地区与北极地区存在着古气候的遥相关。

Abstract:

The period of time between 65.0 ka B.P.to 42.0 ka B.P.corresponds to early stage of the last glacial period or the time between the late period of the marine core oxygen isotope 4 stage and the early-middle period of the marine core oxygen isotope 3 stage.The time sequence of paleoclimatic change from 65.0 ka B.P.to 42.0 ka B.P.in the last glacial period has been established by the dating ages of the high precision TIMS-U series and the analysis of the oxygen isotopes from D42 stalagmites of Dongge Cave in Libo,Southern Guizhou.The result indicated that the monsoon-climate change reflected by the cold and warm events of the stalagmite record during 65.0 ka B.P.and 42.0 ka B.P.can be divided into three stages of climate change:(1) the late period of the marine core oxygen isotope 4 stage from 65.0 ka B.P.to 60.6 ka B.P.reflected that the East Asian winter monsoon was the more strength in this stage,the air temperature was lower,the available rainfall reduced and represented the dry and cold climate environment in this stage;(2) the early period of the marine core oxygen isotope 3 stage from 60.6 ka B.P.to 48.4 ka B.P.reflected that the East Asian summer monsoon was stronger in this stage,the air temperature was high,the available rainfall relatively reduced in summer season and represented the semiarid-semihumid and warm climate environment in this stage;(3) the middle period of the marine core oxygen isotope 3 stage from 48.4 ka B.P. to 42.0 ka B.P.reflected that the East Asian winter monsoon was stronger in this stage,the air temperature was lower,the rainfall reduced and represented the dry and cold-cool climate environment in this stage.The stalagmite record revealed that there were records of two cold events in the various sediments,which reflected the climate event of the global change and corresponded to the cold events of Heinrich 5 and Heinrich 6 in the sediment of the north Atlantic.It can be compared to the global change and had well tele-connection with the paleaoclimate change in the North pole region.