川西金川地区第四纪风尘堆积的古气候记录研究

The discovery of an eolian sequence in the Jinchuan county of Sichuan province (with a basal age of about 2.84 Ma) changes the traditional concept that eolian accumulation in the east margin of the Tibetan Plateau has formed in the late Early Pleistocene (with a basal age of about 1.15 Ma). This eolian sequence provides ideal material for revealing the paleoclimatic evolution during Quaternary in the Southwest monsoon region. In this subject, based on our previous magneto stratigraphic result, multiple environmental indexes such as magnetic susceptibility, chromaticity, grainsize, free iron oxide and iron oxide will be measured to establish the time series of paleoclimate evolution since Quaternary in this area. Then, the paleoclimate evolution information is to be extracted at different time scales and major climatic events that occur during this period are to be identified. Finally, by comparing these results with existing paleoclimatic records in other regions, we hope to explore the relationship among the climatic events in this area and the global or regional major environmental events and the uplift of the Tibetan Plateau. This subject is of great significance not only for paleoclimatic construction in the Southwestern summer monsoon area, but also for understanding the environmental response to the uplift of the Tibetan Plateau.

川西高原金川地区底界年龄约为2.84Ma的风尘堆积剖面的发现打破了青藏高原东缘风尘堆积主要形成于早更新世晚期（底界年龄约为1.15Ma）的传统认识，为西南季风区第四纪古气候演化研究提供了理想材料。本项目以金川风尘堆积为研究对象，在前期磁性地层学研究的基础上，通过磁化率、色度、粒度、游离氧化铁/全氧化铁等指标的测试分析，建立该区第四纪以来古气候演化的时间序列，识别在此期间发生的重大气候环境事件；通过与其它地区已有的研究成果进行对比，探讨西南季风区气候环境事件与全球或区域性重大环境事件及青藏高原隆升的可能联系。此项研究不仅对西南季风区第四纪古气候重建有重要意义，而且对青藏高原隆升的环境响应过程与机制研究也有重要价值。

川西高原金川地区底界年龄约为2.84Ma的风尘堆积剖面的发现打破了青藏高原东缘风尘堆积主要形成于早更新世晚期的传统认识，为西南季风区第四纪古气候演化研究提供了理想材料。本项目以金川风尘堆积为研究对象，在前期磁性地层学研究的基础上，通过磁化率、色度、粒度、游离氧化铁/全氧化铁等指标的测试分析，识别出适用于川西高原古气候研究的环境指标体系，建立该区第四纪以来古气候演化的时间序列。在综合磁化率、色度、粒度、FeD／FeT环境指标测试结果的基础上，将该区古气候演化划分为2.84~0.8 MaB.P.，0.8~0.5 MaB.P.，0.5 MaB.P.至今三个阶段，识别出S4、S5、S9、S11、S22、S25等气候典型暖湿时期以及L6，L9，L13，L14，L23和L27等气候典型干冷时期。将金川剖面与黄土高原典型风尘堆积剖面、川西高原甘孜风尘堆积、云南鹤庆盆地湖相沉积记录开展对比研究，揭示出西南季风演化与东南季风演化差异性、西南季风区不同地区古气候演化差异性，证明青藏高原隆升运动对不同地区的环境效应影响是不同的。