Distribution Characteristics of Glycerol Dialkyl Glycerol Tetraether Lipids in Lake Dianchi Sediments

Key words: 
• glycerol dialkyl glycerol tetraether lipids

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.