Climatic significance of δ13C record of organic matters in the paleosol from the Yuanbao Holocene profile, Gansu Province
HE Yong1, QIN Da he2, REN Jia wen2, LI Feng xia2 (1. Chinese Academy of Sciences Key Laboratory of Regional Climate Environment Research for Temperate East Asia, START Regional Center for Temperate East Asia, Institute of Atmospheric Physics, Beijing 100029, China; 2. Key Laboratory of Ice and Cold Regions Environ ment, Cold and Arid Regions Environmental and Engineering Research Institute, Chinese Academy of Sciences, Lanzhou 730000, China)
The values of δ13C of organic matters in the paleosol from the Yuanbao Holocene profile, Linxia, Gansu Province are between -28.23‰to -25.19‰, with an average of -26.88‰. Combining with the pollen and stratum records at the same profile, it is shown that high δ13C are corresponding to warm and humid climate, and low to cold and arid climate, which means that the δ13C of organic matters in the paleosol can reflect the Holocene climatic evolution at the study area by recovering the vegetation change. With other research conclusions, it is confirmed that the ratio variation of C3 and C4 of the surface plants mainly affected the δ13C change of organic matters in the paleosol, and climate change resulted change of the vegetation type and the carbon isotope composition. Comparing the δ13C researches from the Xian and Xunyi profiles, Shaanxi Province, the δ13C average values at the two profiles are about 5‰higher than that at the Yuanbao profile, suggesting higher temperature and precipitation occurred at Xian and Xunyi during Holocene. It is concluded that the carbon isotope composition of organic matter in the paleosol is also an indicator for the paleoclimatic change.