【摘要】 具有精准年代控制的高分辨率气候记录对于深入研究小冰期气候变化规律具有重要意义。文章基于黔南荔波县董哥洞D41石笋（研究部分长约11.7 cm）的24个U-Th绝对定年和1165组碳、氧稳定同位素测试数据,得到明清小冰期期间（公元1400-1880年）平均分辨率高于0.5年的洞穴上游水汽传输路径的空间集成降雨量变化记录。重建记录表明小冰期内部气候变化存在着多年代际-百年尺度变化趋势和年际-年代际波动;次级波动与干旱事件、火山活动的响应表明石笋δ¹⁸O能够反映一定的大尺度气候信号。D41石笋的δ¹⁸O序列功率谱分析结果显示出160年、11.5年、9年以及14～16、4～7年周期,可能反映了太阳活动和ENSO等地球气候系统内部变率的影响。中国南北方多根石笋氧同位素记录的对比表明崇祯大早期间（公元1628-1643年）石笋记录显示出与历史文献资料类似的干旱边界,从南方至北方水汽传输路径上,干旱状态反映的空间集成降雨量减少可能是引起北方石笋氧同位素偏重的主要原因。另外,石笋氧同位素记录在年际-年代际尺度上明显的区域差异表明在短尺度上将单个洞穴石笋氧同位素记录用作亚洲季风强度指标时需要谨慎。更多还原

【Abstract】 High-resolution and precisely dated climate records are important to further investigate the climate variability during the Little Ice Age（LIA）.On the basis of 24 230 Th dates and 1165 oxygen and carbon isotope data obtained from stalagmite D41（sample length for 11.7 mm）from Dongge Cave（25°17′50.5″N,108°02′67″E）,Libo,Guizhou,we present here a high-resolution（average resolution better than 0.5 year）δ¹⁸O and δ¹³C record across a large portion of the LIA（1400～1880 A.D.）.The δ¹⁸O values in the D41 record vary from-8.19‰ to-6.64‰ with the average value of-7.52‰.There exists a significant positive correlation between the δ¹⁸O and δ¹³C（Pearson linear correlation coefficient r=0.7882,n=1165,p<0.001）.The δ¹⁸O record shows low excursions during the periods of 1450 ～ 1555 A.D.and 1630～1780 A.D.,and high excursions during 1400 ～ 1450 A.D.and 1555 ～ 1630 A.D.,with interannual-decadal fluctuations between throughout the record.Power spectrum analysis of the D41 δ¹⁸O revealed periodicities of 160,11.5 and 9 years similar to solar radiation cycles,as well as periodicity of 4～7 years similar to the ENSO cycle.Additionally,a 14 ～ 16-year periodicity appears to be prominent,which may reflect the influence of sea-air circulations and other interaction between different Earth’s climate systems.In principle,the lower δ¹⁸O in the D41 record may mainly reflect larger spatially integrated rainfall between the cave site and moisture source along water vapor transmission path.The secondary fluctuations of the D41 δ¹⁸O variance may response to large-scale volcanic and drought events.A close look at different stalagmite δ¹⁸O records during the Chongzhen Drought（1628～1643 A.D.）reveals a drought/wet boundary in line with the historical documents.We suggest that the significant differences of δ¹⁸O in stalagmites could be explained by the change of spatial integrated rainfall between the cave site and its upstream rainfall along the moisture transmission path.As such,the high excursions observed in cave δ¹⁸O records from northern China,compared with the absence of the equivalent events in cave δ¹⁸O records from southern China during the Chongzhen Drought event,suggest that the rainfall reduce during the event occurred mainly between the northern and southern cave sites,broadly consistent with the historical documents.Moreover,observations of the temporal and spatial difference between different stalagmite δ¹⁸O records call for a caution to use a single stalagmite δ¹⁸O record as an indicator of Asian Monsoon intensity on annual to decadal timescales.更多还原