湖泊沉积物粒度分析方法在古气候环境研究中的应用

沉积物的粒度是衡量沉积介质能量和沉积盆地能量的一种重要代用指标,与沉积环境的关系非常密切,在古气候古环境研究中,湖泊沉积物的粒度指标发挥着重要的作用。刘兴起等人利用全样粒度分析方法对青海湖QH-2000钻孔的沉积物粒度特征进行了详细研究,结果表明冷干和暖湿气候条件下沉积物的粗颗粒组分增多,介于二者之间的气候条件下,沉积物的粒径变化相对比较平缓。Xiao Jule等利用正态函数分布拟合法,将Dali湖沉积岩心的粒度组分划分为6种,通过对各组分峰值粒径等粒度参数的分析研究,得出各组分含量及其峰值粒径等的变化与湖泊水位关系密切。根据建立起的湖泊沉积物粒度参数与气候环境之间的耦合关系,最后将达里湖1.2kaBP以来的水位波动划分为不同的5个阶段。

THE APPLICATION OF GRAIN SIZE OF LAKE SEDIMENTS IN RECONSTRUCTING THE PALEOCLIMATE AND PALEOENVIRONMENT

The grain size of sediments is one of the most important indications in predicating the energy of deposit medium and deposit basin, which correlates well with the deposit environment. The grain size of lake sediments play an important role in the study of paleoclimate and paleoenvironment. Liu et al used whole-sample grain size analysis in the study of core QH-2000 （Qinghai Lake）, which show that the coarse grain obviously increases in the sediments formed in the conditions of cold-dry and warm-moist climate and the grain variation is relatively little in the sediments formed between these two climate conditions. In the use of normal distribution function fitting, Xiao et al divided the sediment core of Dali lake into six components. Through the analysis of peak grainsize of the sediments, they deemed that the parameters such as the peak grainsize correlates closely with the lake level. Based on the established coupling relations between the grain size and the paleoclimate and paleoenvironment, the authors divided the lake fluctuation periods into five stages since 12000 years before present.