Variation Characteristics and Influencing Factors of Organic Carbon Isotope from Palaeolake Sediments in Hoh Xil Area

Key words: 
• Hoh Xil area /
• lake sediments /
• stable isotope compositions of organic carbon (&delta /
• ¹³C) /
• influencing factors

Abstract: A multiproxy record, including grain size, organic carbon and nitrogen, and the stable isotope compositions of organic carbon(δ¹³C) obtained from Core BDQ06 in the marginal Hoh Xil area, Tibet Plateau, provided evidence for climate change since mid-Pleistocene. The influencing factors and variation characteristics of organic carbon isotope were reviewed. The organic carbon content is controlled by autophyte from lake. The variation of organic carbon isotope is mainly related to the ratio of emergent plant to submerged plant, indicating fluctuation of lake level. Variations of the δ¹³C can be used to estimate various sources of organic matter in the aquatic environment. The higher δ¹³C values and lower C/N ratios show the dominance of the submerged plant in the lake, and may reflect higher lake level and more moderate climate. The lower δ¹³C values is attributed to contributor of emergent aquatic plant and planktont, which used atmospheric CO₂ for photosynthesis, indicating lower lake level and drier climate. Additionally, in certain phases, lower δ¹³C values corresponding to the C/N ratios of more than 10 may be related to the input of terrestrial higher plant.