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

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• 作者：Chang Fengqin ; Zhang Hucai ; Chen Yue ; Yang Mingsheng ; Niu Jie ; Fan Hongfang ; Lei Guoliang ; Zhang Wenxiang ; Lei Yanbin ; Yang Lunqing
• 关键词：Qaidam basin ; stable oxygen and carbon isotopes ; paleoenvironment
• 刊名：Journal of China University of Geosciences
• 出版年：2008
• 出版时间：February 2008
• 年：2008
• 卷：19
• 期：1
• 页码：1-8

文摘

On the basis of the analyses of TOC, CaCO₃, δ¹³C_org, 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, δ¹³C_org 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.