Sedimentation Geochemistry and Environmental Changes during the Late Pleistocene of Paleolake Qarhan in the Qaidam Basin  

作　　者：常凤琴 张虎才 陈玥 杨明生 牛洁 樊红芳 雷国良 张文翔 类延斌 杨伦庆 

机构地区：[1]Key Laboratory of Western China's Environments, Ministry of Education, College of Earth Sciences and Environments, Lanzhou University [2]State Key Laboratory of Lake Science and Environment, Nanjing Institute of Geography and Limnology, Chinese Academy of Sciences [3]Key Laboratory of Western China’s Environments, Ministry of Education, College of Earth Sciences and Environments, Lanzhou University

出　　处：《Journal of China University of Geosciences》2008年第1期1-8,共8页中国地质大学学报（英文版）

基　　金：the Hundred Talent Project by Chinese Academy of Sciences;the National Natural ScienceFoundation of China (No. 40371117);NSFC Innovation Team Project (No. 40421001)

摘　　要：On the basis of the analyses of TOC, CaCO3, δ13Corg, δ18O, and δ13C of the shell bar section in the Qaidam basin, and compared with grain size data, the environmental change history of the high water level of paleolake Qarhan was reconstructed and it could be divided into five stages. From 39.7 to 35.8 kaBP was the development period of high paleolake level. From 35.8 to 33.6 kaBP and 33.6 to 27.2 kaBP, TOC and CaCO3 contents and δ18O values were high, whereas, δ13Corg values and median size content were low, reflecting a warm-humid climate and high lake level. During 27.2-22.3 kaBP and 22.3-17.5 kaBP, both temperature and the lake level were lower than those in the previous stages, but the climate was still warmer and more humid than that of today. The lake level decreased between 32.4 and 32.2 kaBP, 30.4 and 29.8 kaBP, and 28.4 and 27.2 kaBP. Generally, the climate was warm and humid in Qaidam basin and the high lake level sustained between 39.7 and 17.5 kaBP. The lake retreated abruptly at 17.5 kaBP, with a very strong increase in evaporation, which resulted in salt formation and the extinction of Corbicula.On the basis of the analyses of TOC, CaCO3, δ13Corg, δ18O, and δ13C of the shell bar section in the Qaidam basin, and compared with grain size data, the environmental change history of the high water level of paleolake Qarhan was reconstructed and it could be divided into five stages. From 39.7 to 35.8 kaBP was the development period of high paleolake level. From 35.8 to 33.6 kaBP and 33.6 to 27.2 kaBP, TOC and CaCO3 contents and δ18O values were high, whereas, δ13Corg values and median size content were low, reflecting a warm-humid climate and high lake level. During 27.2-22.3 kaBP and 22.3-17.5 kaBP, both temperature and the lake level were lower than those in the previous stages, but the climate was still warmer and more humid than that of today. The lake level decreased between 32.4 and 32.2 kaBP, 30.4 and 29.8 kaBP, and 28.4 and 27.2 kaBP. Generally, the climate was warm and humid in Qaidam basin and the high lake level sustained between 39.7 and 17.5 kaBP. The lake retreated abruptly at 17.5 kaBP, with a very strong increase in evaporation, which resulted in salt formation and the extinction of Corbicula.

关 键 词：Qaidam basin stable oxygen and carbon isotopes paleoenvironment. 

分 类 号：P534.631[天文地球—第四纪地质学]