【摘要】 以云贵高原浅水湖泊—滇池作为研究对象,在对湖心一个63 cm沉积物柱样的有机质总体及分子有机地球化学研究的基础上,对沉积物有机质中甘油二烷基甘油四醚脂(GDGTs)组成进行了测定。研究结果表明,滇池湖泊沉积物中具有丰富的GDGTs,且以反映陆相土壤来源的支链类GDGTs为主。该沉积柱样中支链类GDGTs的环化指标(CBT)和甲基化指标(MBT)揭示出:1)整个沉积阶段滇池流域土壤的pH值主要介于7.5～8.2,相对中、下部层段,上部层段pH值呈现略微减小的趋势;2)基于CBT/MBT重建的滇池流域内年平均气温呈现由早期的温暖潮湿气候逐渐向寒冷干燥气候变化,近来又有所回暖的变化过程,这可以很好地解释该沉积柱中、下层段记录的总体有机质主要特征的演化规律。更多还原

【Abstract】 Glycerol dialkyl glycerol tetraether lipids in the Lake Dianchi sediments were determinated based on bulk and molecular organic geochemical analyses of a lake sediment core(63 cm in length).The results indicate that the Lake Dianchi sediments have abundant GDGTs,and are dominated by the branched GDGTs from terrestrial soils.Methylation and cyclisation indices of branched tetraethers in this core samples reveal that 1) during the whole depositional stage of the core DC-4,soil pH values of Lake Dianchi watershed are in the range of 7.5~8.2.Compared with the lower and middle section,the upper section has relatively low pH.2)reconstructed mean annual air temperature of the Lake Dianchi watershed based on CBT/MBT displays a trend of changing from warm and moist climate in the early stage to cold and dry climate,and then become warm again lately.This variation can be used to explain the characteristics of bulk organic matter recorded in the lower and middle section of the core.更多还原