湖北落水洞倒三冰期事件与轨道背景关系研究

倒数第三次冰期千年尺度事件与轨道尺度旋回的耦合过程是理解第四纪突变气候事件动力学机制的关键。限于记录载体、测年和分辨率等因素，目前对这一关键科学问题存在不同的证据和认识。本项目拟以湖北恩施落水洞多支石笋为研究材料，通过高精度230Th测年和高分辨率石笋氧、碳同位素分析，研究倒三冰期千年尺度季风事件的振幅和时频特征。拟解决以下两个科学问题：(1)倒数第三次冰期千年尺度事件是否具有末次冰期Dansgaard-Oeschger旋回？这对分析冰漂碎屑事件与Dansgaard-Oechger旋回的成因联系有重要启示意义。(2)综合过去四个冰期旋回千年尺度事件的基本特征，并与高分辨率南极冰芯记录进行对比，进一步明晰第四纪冰期旋回千年尺度事件的基本规律和全球性特征。上述研究工作有助完善太阳辐射和地球内部边界条件(如冰量)对千年尺度事件制约的相关理论，并为评估自然变率下未来长期气候变化提供参考。

The coupling processes of millennial-scale events and orbital-scale cycles in the antepenultimate glaciation is critical to understand the dynamics of Quaternary abrupt climate variability. Discrepancies still exist in evidences and understandings on this key scientific problem, as limited by different geological archives, dating methods and proxy resolution. This project intends to investigate the amplitude and time-frequency characteristics of the millennium-scale Asian monsoon variability during the antepenultimate glaciation, based on the high-precision 230Th dating and the high-resolution analyses of oxygen and carbon isotopes of the stalagmites from Luoshui cave, Hubei Province. Two targeted problems are listed as follows: (1) detecting discernable and reliable millennium-scale Dansgaard-Oscheger cycles during the antepenultimate glaciation, in order to understand the mechanism and relationship between ice-rafted debris events and Dansgaard-Oscheger cycles; (2) based on comparison with the high-resolution Antarctic ice core records, summarizing the characteristics of the millennial-scale events in the past four glacial cycles, and further clarifing the basic rules and global characteristics of the millennial-scale events during the Quaternary glacial cycles. The above research work helps to improve the relevant theories how insolation and the ice volume control the millennium-scale events, and provides a reference for evaluating long-term climate change under natural variability in the future.