Groundwater discharge to a Gobi desert lake during Mid and Late Holocene dry periods

摘要

High levels of Lake Eastern Juyanze and a wetter climate in the Gobi desert (NW China) were recorded between 5 100 and 4100 cal. year BP from ostracod distribution, shell geochemistry, sedimentology and palynological data. After about 4100 cal. year BP lake levels decreased and groundwater discharge became dominant source of water during short-term regressive events at about 4000, 3800 and 3500 cal. year BP as suggested by a significant difference in modem river water and groundwater chemistry and the geochemical signal of fossil ostracod shells. The overall trend towards lower lake levels culminated in repeated episodes of desiccation of Lake Eastern Juyanze between 3200 and 2900 cal. year BP. Individual regressive events as well as the rapid environmental fluctuations of Lake Eastern Juyanze at about 3000 cal. year BP were likely caused by Mid to Late Holocene temperature fluctuations, recorded by the Dunde ice core [Yao, T., Thompson, L.G., 1992. Trends and features of climatic changes in the past 5000 years recorded by the Dunde ice core. Annals of Glaciology 16, 21-24] and shifts of the southeastern Asian monsoon. (c) 2005 Elsevier B.V. All rights reserved.