CHEN Shiyue),WANG Sumin),JIN Zhangdong),SHEN Ji)) Nanjing Institute of Geography, Limnology, Chinese Academy of Sciences, Nanjing, Jiangsu, ) School of Environment, Planning, Liaocheng University, Liaocheng, Shandong,.2004. Geochemical Records of Environmental Evolution in the Last 2. 8 Ma from the Co Ngoin, Central Tibetan Plateau[J]. Acta Geologica Sinica,78(2):234-241