MIS5阶段华北石笋记录的千年-亚千年尺度季风变化及驱动机制研究

Marine Isotope Stage (MIS) 5, a period of relative small ice-sheet extent, larger seasonal insolation changes and high CO2 concentrations, was characterized by remarkable long and low-frequency Dansgaard-Oeschger (DO) events compared to MIS3. Full understanding of the links between two polar climate systems and Asian monsoon on the millennial to multi-decadal scales, under conditions of extending ice sheet coverage over the high northern latitudes, is ciritical to shed light on the forcing mechanisms for abrupt climate changes. Here we present a new absolute-dated high resolved cave oxygen isotope record in Shanxi province, North China, continuously covering the whole MIS5 from 130 to 70 ka BP. These new data allows us to investigate the timing, amplitude, duration, structure and sub-cycles of both D-O and Heinrich events in unprecedented detail. We will compare our record with the bipolar ice cores records, sea-level record, insolation and the other independent-dated cave records in Asian monsoon areas to evaluate the spatial and temporal pattern of these abrupt climate changes during MIS5 and explore the driving mechanisms of North high hemisphere climate, low latitude tropical hydroclimate, and South ocean thermal reservoir in influencing the EASM abrupt climate changes.

末次冰期早期千年尺度气候突变事件的高分辨率重建有助于深入理解高、低纬相互作用以及海-气耦合过程对突变事件的制约。本项目拟通过华北黄土高原东缘洞穴石笋研究，重建深海氧同位素5 期（MIS5）130~70 kaBP高精度、高分辨率东亚季风演化序列，诊断气候突变事件在华北地区的表现形式与变化幅度，精确标定DO25-20季风增强事件的起止时间，剖析突变事件转型模式和亚旋回特征；通过与两极冰芯记录、海平面记录、太阳辐射能量变化以及亚洲季风区不同区域记录的综合对比，确立在MIS5 冰量较小条件下两极高纬气候和低纬季风环流在千年－百年际尺度上的响应与耦合关系，探讨千年－亚千年尺度季风突变事件的成因机制。

深海氧同位素5阶段（MIS5）千年尺度气候突变事件的高分辨率重建有助于深入理解高、低纬相互作用以及海-气耦合过程对突变事件的制约。本项目通过山西龙洞石笋高精度230Th定年以及高分辨率氧同位素分析，重建了130ka BP-70ka BP时段的东亚夏季风演化序列，重点分析了千年-百年尺度亚洲夏季风突变事件旋回变化特征，并获得了以下认识：（1）末次间冰期（MIS5e）石笋δ18O值最为偏负，指示了该时期夏季风强度最强，随后逐渐减弱。石笋δ18O记录伴随着北半球夏季太阳辐射变化而变化；（2）在MIS5阶段，山西石笋δ18O记录清晰的揭示出连续的DO25-19强季风事件；（3）类似于末次冰期其它DO 事件，DO25季风事件是一个普通的季风增强事件，其内部可进一步细化为DO25a,b,c 3个亚旋回，与格陵兰冰芯记录一一对应；（4）精细对比南、北半球单个DO事件，发现其百年尺度季风强、弱波动快速响应于北高纬气候变化，而其长期趋势变化又联系与南半球高纬变化。