A Late Quaternary Climate Record Based on Multi-Proxies Analysis from the Jiaochang Loess Section in the Eastern Tibetan Plateau,China

We compared the stable carbon isotopic records from a loess transect of the Jiaochang in the eastern Tibetan Plateau,spanning the last～21,000 years,with multiproxy data for pedogenesis, including magnetic susceptibility,clay fraction,Fe/Feratio,carbonate and total organic carbon content,in order to probe the mechanisms ofδC values of organic matter and Late Quaternary climate variations in the eastern Tibetan Plateau.Our results indicate that there is no simple relationship betweenδC of organic matter and summer monsoon variations.The change inδC values of organic matter(in accordance with the ratios of Cto Cplants)results from the interaction among temperature,aridity and atmospheric pCOlevel.Drier climate and lower atmospheric pCOlevel contribute to positive carbon isotopic excursion,while negative carbon isotopic excursion is the result of lower temperature and increased atmospheric pCOlevel.Additionally,our results imply that the Tibetan monsoon may play an important role in climate system in the eastern Tibet Plateau, which specifically reflects frequently changing climate in that area.The results provide new insights into the forcing mechanisms on both theδC values of organic matter and the local climate system.