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基于陕南祥龙洞石笋XL2的19个~(230)Th年龄、218个氧同位素分析以及896个Sr/Ca分析数据,高分辨率重建了4200~1972a B.P.期间陕南地区季风降雨变化。重建结果显示陕南地区这一时期季风降雨有显著的127~105a和57a周期,可能分别受控于太阳活动、PDO和/或AMO的变化。重建时段有3次百年尺度的干旱事件,分别发生于2200~2100a B.P.,2900~2700a B.P.和3600~3400a B.P.,其中2900~2700a B.P.干旱事件对应于北大西洋地区2.8ka冷事件。对比研究显示,尽管祥龙洞石笋和董哥洞石笋δ~(18)O记录整体一致,但除了2900~2700a B.P.干旱事件之外,其他两次干旱事件在董哥洞石笋记录中并不明显。而尽管总体上祥龙洞和和尚洞石笋δ~(18)O记录的差异要大,但XL2的3次干旱事件在和尚洞记录都有明显体现。有精确年代控制的祥龙洞、董哥洞及和尚洞石笋氧同位素记录的差异,揭示晚全新世我国季风降雨在十-百年尺度存在区域差异。
Based on 19 ~ (230) Th ages, 218 oxygen isotope analyzes and 896 Sr / Ca analysis data from the stalagmite XL2 in Xianglong Cave, southern Shaanxi, the monsoon rainfall was reconstructed from 4200 to 1972a B.P. with high resolution. The reconstructed results show that the monsoonal rainfall in southern Shaanxi during this period has significant periods of 127-105a and 57a, which may be controlled by changes in solar activity, PDO and / or AMO, respectively. There are three hundred-year-scale drought events during the reconstruction period, which occurred in the period of 2200 ~ 2100a B.P., 2900 ~ 2700a B.P. and 3600 ~ 3400a B.P., of which the 2900 ~ 2700a B.P. drought event corresponds to the 2.8ka cold event in the North Atlantic. The comparative study shows that although the δ 18 O records of the stalagmite in Xianglong Cave and Dongge Cave are consistent, the other two drought events except the 2900-2700 a B.P. drought are not obvious in the stalagmite records of Dongge Cave. Although the difference of δ 18 O records of the Xianglong Cave and the Heshang Cave stalagmites was generally large, the three drought events of XL2 were clearly reflected in the records of the monk Cave. The differences of the oxygen isotopic records of the stalagmite of the Xianglong Cave, Dongge Cave and the Heshang Cave controlled by the precise chronology reveal the regional differences of the monsoon rainfall in the late Holocene at the ten-hundred-year scale.