末次冰期贵州七星洞石笋高分辨率气候记录与Heinrich事件

The High Resolution Climate Records from Two Stalagmites in Qixing Cave of Guizhou and the Heinrich Events of the Last Glacial Period

通过对贵州都匀七星洞Q4、Q6石笋进行高精度的TIMS U系测年和氧同位素分析 ,建立了末次冰期 6 0 .5kaBP以来都匀凯酉地区高分辨率的古气候变化时间序列。通过与格陵兰GISP2冰心的δ18O曲线对比分析 ,初步揭示并探讨了末次冰期以来反映的短时间尺度气候快速变化的D O旋回事件 1～ 18和Heinrich事件H1～H5在黔南七星洞中的石笋记录 ,并对冷事件发生的年代给出了界定。研究表明 ,黔南 6 0 .5kaBP以来石笋记录冷暖事件所反映出的古季风环流变化 ,明显受北大西洋气候振荡的影响 ,显示与北极地区存在着古气候的遥相关。石笋δ18O记录表明 ,在 6 0 .5～ 11.2 9kaBP间的末次冰期 ,δ18O值由负偏逐渐向正偏方向变化 ,反映东亚夏季风由强变弱 ,降雨由多变少 ,气温由高变低的变化趋势。

The time sequence of high resolution paleo-climatic change since the last glacial period-60.5 ka B P-was reconstructed by means of high precision TIMS-U series dating and oxygen isotope analysis of Q4 and Q6 stalagmites from Qxing cave in southern Guizhou. Through a comparative analysis of δ 18 O curves between the GISP2 ice core and two (Q4 and Q6 ) stalagmites from Qixing cave, the depositional records of the Dansgaard-Oeschger cycle events 1～18 and Heinrich events H1—H5 from the records of two stalagmites in southern Guizhou which can reflect rapid climate change in short time scale since the last glacial stage were preliminarily revealed and discussed, and the ages of the cold events were determined. The results have shown that the records of the cold and warm events from two stalagmites since 60.50 ka B P in southern Guizhou are reflections of the paleo-monsoon circulation changes, and that these changes are clearly affected by the climate oscillation of the North Atlantic Ocean. This suggests that they are obviously related to the paleo-climate changes in the North pole region. The records of δ 18 O from the Q4 and Q6 stalagmites indicate that theδ18O values from 60.59 ka B P to 11.29 ka B P changed from somewhat negative to relatively positive in the last glacial period, and suggest that the Asian summer monsoon gradually weakened and the climate tended to become drier and cooler.