基于神农架三宝洞两支石笋24个230Th年龄以及637个δ13C测试数据,建立了倒数第二次冰期191±1.8～133±0.6kaB.P.时段洞穴石笋高分辨率δ13C的时间序列.在冰期/间冰期尺度上,δ13C值振幅达4.5％,整体变化趋势与全球冰量曲线类似.在倒数第二次冰期,石笋δ13C记录揭示出一系列较大振荡幅度的千年尺度气候事件,并且与北大西洋SST记录的倒数第二次冰期9个千年尺度冷暖事件一一对应,至在某些DO亚旋回事件上也具有一定的对应关系.倒数第二次冰期北大西洋6个冰漂碎屑事件也在三宝洞石笋δ13C记录中留有印迹.三宝洞石笋δ13C记录将末次冰期东亚季风气候与北大西洋气候的联系拓展至倒数第二次冰期,进一步说明倒数第二次冰期北大西洋温盐环流对季风气候仍然起着中重要的作用.%The study of millennial-scale abrupt climate change has focused mainly on the last glacial period and provided important insights about the dynamics of the climate system. Some of these records also suggest that high-frequency climate variability was not restricted to this period. Previously studies on the Shennongjia Caves demonstrated a strong correlation with Greenland climate during the last glacial. However,it was not clear whether the millennialscale temperature changes in the North Atlantic exert significant influence on the ASM during the penultimate glacial. An understanding of MIS 6 climate may help to unravel the underlying dynamics that control glacial climate variability.Sanbao Cave (31°40'N, 110°26'E) is located at an elevation of 1902m on the northern slope of Mt.Shennongjia ,near the southern edge of the Chinese Loess Plateau. The cave site is strongly influenced by East Asian summer monsoon ( EASM ) which brings the greatest amount of moisture to the region. The mean annual precipitation at the site ranges between 1500mm and 2000mm,60％- 80％ of which falls between Jun. and Sep. Relative humidity in the cave is 95％ - 1OO％ and cave temperatures (9℃ ) approximate a mean annual temperature of outside atmosphere.Two stalagmites( SB24 and SB42 ) recovered from Sanbao Cave in Shennongjia , China , established with 24 230Th ages and 637 δ13C data, provides a continuous, high-resolution, precisely dated palaeoclimate record covering the coldest part of the penultimate glacial( 191±1. 8 ～ 133±0. 6kaB. P. ) . 637 sub-samples for δ13C measurements were run at the Isotope Laboratory of Nanjing Normal University with on-line automated carbonate preparation system ( Kiel Carbonate Device)linked to Finnigan MAT-253 , yielding a standard deviation error of 0. 05‰. Twenty-four 230Th dates were conducted at the Isotope Laboratory of Geology and Geophysics Department, University of Minnesota , USA. The reported error is in±2σ .Stable carbon isotope ratios from Sanbao Cave show prominent orbital- to millennial-scale variations.which is interpreted in terms of changes in soil biological activity, mainly controlled by the temperature. Comparison to Sanbao δ18O and global ice volume , the two proxies( δ13C and δ18O ) are regulated by two different orbital thythms.The Shennongjia temperature responds predominantly to the global ice volume. whereas the AM rainfall vigor oscillates at the precession cycle.Sanbao δ13C exhibits largely and clearly millennial-scale oscillations. which could be correlated to the DO events off the Western Iberian margin. Six ice rafting debris in the North Atlantic are also imprinted in stalagmite δ13C profile. We show for the first time that specific millennial-scale climatic events occurred more or less synchronously between AM and Northern Atlantic. These spatially correlated events suggest that the millennial-scale fluctuations would be of global significance,supporting the conclusion that North Atlantic Thermohaline Circulation exerted an important influence in the AM.
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