MIS3晚期石笋记录的季风突变事件区域特征及全球联系

末次冰期晚期短尺度气候突变事件异常显著，对其研究有助于认识相似边界条件下气候突变规律。通过MIS3晚期亚洲季风区8支石笋记录总结分析发现，因受洞穴微环境、渗水通道、生长动力等影响，DO5~DO3事件振幅差最大可达0.9 ‰，持续时间差最大达到900年，这可能反映局地环境对同一气候信号的改造作用或与各记录分辨率及测年精度有关。同时，统计分析发现，这些短尺度DO事件具有一定相似性，其持续时间集中分布于特定范围，说明石笋同位素信号在某种程度上可以反映真实气候信号。高、低纬记录对比显示，石笋记录与低纬气候信号呈现诸多相似性，反映亚洲季风区石笋记录具有显著的"低纬特色"。因此，无论亚洲季风突变的"开关"是否归因于北高纬气候，低纬过程确实是不可或缺的"塑造者"。

Regional characteristics of abrupt monsoon changes in late MIS3 and its global significance

In this study, eight stalagmite δ18O records were chosen from seven caves from the Asian Summer Monsoon (ASM) region. The geographical location of these cave sites ranges from 26°N to 33°N, and 105°E to 120°E, with a sufficient spatial coverage. From north to south, sample MSD is from Hulu Cave (32°30'N, 119°10'E), XR025 from Xianren Cave (32°24'N, 107°10'E), SB46 from Sanbao Cave (31°40'N, 110°26'E), YX51 from Yongxing Cave (31°35'N, 111°14'E), QT15 from Qingtian Cave (31°20'N, 110°22'E), DSB3 from Dashibao Cave (26°05'N, 105°03'E), Wu3 and Wu32 from Wulu Cave (26°03'N, 105°05'E). Apparently, site-specific karstic conditions, microclimate, soil cover and vegetation types, etc., are strikingly different at these sites, probably inducing contrasting expressions of regional climate events. These stalagmite records, mainly spanning the late MIS3 (34~27 ka B.P.), are characterized by high-resolution data and precisely-constrained chronologies, which are suitable for detecting the internal structure of short-lived abrupt ASM changes. Generally, in our studied interval, the chronologies of these records were constrained by more than three U/Th dating results, with dating uncertainties of less than 200 years. Sampling resolution is better than 40 years or even 5 years on QT15. Millennial-scale climate events in these stalagmite records, include Dansgaard-Oeschger (DO) 5 to DO3 and Heinrich event (H) 3. Regardless of the observed resemblance between DO events, regional differences can be observed in amplitude and duration. By statistical analysis, a deviation of 0.7 ‰ in amplitude and 400 years in duration was estimated between different records. To some degree, different microclimates, karstic and environmental conditions can result in these contrasting estimations. At the same time, most (over 60%) of calculated values fall within a narrow envelope, suggesting that DO events from these stalagmite records more likely reflect a true climate signal. δ18O records of samples Wu3 from Wulu Cave, Southern China and SB46 from Sanbao Cave, Central China can be a template for these abrupt ASM changes in the late MIS3.