LI Cuiming ¹ , PENG Hongming ^2,3,4 , MAO Xumei¹, DONG Yaqun¹ , YE Jianqiao¹,ZHA Xixi¹

(1. School of Environmental Studies, China University of Geosciences, Wuhan 430074, China; 

2. Qinghai 906 Engineering Survey and Design Institute Co. , Ltd, Xining 810007, China; 

3. Bureau of Qinghai Environmental Geological Prospecting, Xining 810007, China;

4. Key Laboratory of Geological Environment of Qinghai Province, Xining 810007, China)

Abstract: The karstification in eastern Qinghai is unique in the high-altitude and high-cold tectonic and climatic background of the continuous uplift of the Qinghai-Tibet Plateau. As a climate record file, karst water not only records the changes of paleoclimate, but also reflects the characteristics and changes of karst development. Based on the H, O and C isotope composition of karst water in eastern Qinghai, this paper discusses the changes of temperature and humidity, and reveals the response of karst development in eastern Qinghai under climate change. The results show that the chemical types of karst water in eastern Qinghai are mainly HCO3 -Ca and HCO3 -Ca·Mg types, and the hydrochemical components are derived from the dissolution of carbonate rocks. Karst water is mainly supplied by atmospheric precipitation since the last glacial maximum. From the last glacial maximum to the early Holocene, the overall temperature was low and the rainfall was high. Under the shaping of the planation surface in the geological history stage of the continuous uplift of the Qinghai-Tibet Plateau, a unique alpine-alpine karst landform was formed in the eastern part of Qinghai. Among them, the Qinghai Lake Basin has less rainfall, high temperature, and weak karst development. The Huangshui River Basin has frequent climate changes, low overall temperature and more rainfall. It is the main karst development area, and the karst development is good. In the last glacial maximum, the climate in eastern Qinghai was cold, but the rainfall was abundant and the karst was more developed. Into the post-glacial Holocene, the temperature began to rise, but the rainfall decreased, which limited the intensity and depth of karst development in eastern Qinghai. The last glacial maximum is the main period of surface karst development in eastern Qinghai, and the karst development mode is mainly freeze-thaw and ice splitting.

Key words:groundwater; isotopes; the last glacial maximum; karst development; eastern Qinghai