东北兴凯湖深钻记录的第四纪东亚季风变化历史及高、低纬驱动过程

The East Asian monsoon is an integral part of the global climatic system. The climates (especially monsoon-associated precipitation) in the East Asian monsoon area are important to the maintenance of living environments and socially sustainable development in populous regions of East Asia. Studying Monsoon variability of the past at different time scales can help us to establish how the monsoonal climate system varied under natural conditions and to improve projections of future climate, especially with the present global warming. The current project selected a lake (Xingkai Lake) from Northeast China as study object. This lake is situated mid-latitude continent, and its precipitation is controlled by East Asian monsoon. The aeolian dust from desert/Gobi area from North China and Mongolia can be transported by winter monsoon and trapped by the Xingkai Lake. So the lake sediments from Xingkai Lake could be used to record the history of the East Asian summer/winter monsoon. A long core (320 m) was drilled from Xingkai Lake to reconstruct the palaeoenvironmental and palaeoclimatic changes as well as the East Asian monsoon evolution during the Quaternary. A set of dating techniques, such as magnetostratigraphic dating, 14C, OSL and ESR dating methods, will be used to construct the age framework of the long core; many kinds of proxy analysis, such as grain size, mineral analysis, magnetic susceptibility, elemental and isotopic analysis, pollen, diatom, ostracod, and organic geochemical proxies (compound specific, hydrogen isotope), are proposed to be carried out to reconstruct the Quaternary palaeoenvironmental evolution and the variations of the East Asian summer/winter monsoon. The history of two subsystems of East Asian monsoon will also be compared. Finally, the comparisons of the Xingkai Lake core record and other records from low-latitude and high latitude areas as well as the palaeoclimate modelling at specific time scale, will be conducted to reveal the forcing mechanisms of climatic changes and summer/winter monsoon evolution during the Quaternary.

研究地质时期不同时间尺度上东亚季风的历史和变率及其驱动机制有利于理解全球变暖情景下季风变化趋势及其对我国气候和环境的影响。本项目选择东亚季风影响区的中高纬湖泊兴凯湖为研究对象，充分利用兴凯湖连续深钻 (328 m)岩芯，采用高精度超导古地磁以及14C，OSL和ESR等测年技术，结合天文轨道调谐方法，建立可靠的高精度时间标尺。利用陆源碎屑粒度和沉积通量，沉积物磁学参数，元素地球化学以及同位素地球化学，孢粉，硅藻，介形虫，有机单体化合物及氢同位素等指标，重建研究区第四纪气候环境变化历史，并集成提取东亚冬、夏季风的演变过程、变化韵律以及两者关系。将研究区气候环境变化置于东亚及全球变化框架内，并结合古气候模拟，探讨构造尺度、轨道尺度和千年尺度上气候变化与青藏高原构造隆升、轨道参数、太阳辐射和CO2温室效应等驱动要素之间的成因联系，揭示东亚季风演化的高纬驱动或低纬过程的动力学机制及与全球气候的联系。

研究亚洲季风环流系统的演化历史和对气候变化的影响不仅是国内外学术界关注的重大前沿科学问题，也是我国资源、环境和外交决策的紧迫知识需求。本项目选择东亚季风影响区的中高纬湖泊/兴凯湖为主要研究对象，采用高精度超导古地磁以及AMS 14C，OSL和ESR等测年技术，结合天文轨道调谐方法，建立了兴凯湖328 m岩芯可靠的高精度时间标尺；利用陆源碎屑粒度和沉积通量，沉积物磁学参数，元素地球化学以及同位素地球化学，孢粉，有机单体化合物等指标，重建了我国东北地区第四纪气候环境变化历史，并集成提取东亚冬、夏季风的演变过程、变化韵律以及两者关系；将我国东亚季风区气候环境变化置于全球变化框架内，并结合古气候模拟，探讨构造尺度、轨道尺度和千年尺度上气候变化与青藏高原构造隆升、轨道参数、太阳辐射和CO2温室效应等驱动要素之间的成因联系，揭示了不同时间尺度东亚季风演化与高低纬过程的动力学机制及与全球气候的联系。通过这些关键科学问题的深入研究，提升了我们对东亚季风演化规律的了解和对未来变化趋势的认识，可为解决我国人类社会面临的巨大环境压力和挑战提供科学和技术支持。