Response of karst development in eastern Qinghai to uplift of Qinghai-Xizang Plateau revealed by H and O stable isotopes in water sequestered by weathered soil
The uplift of Qinghai-Xizang Plateau and paleoclimatic changes affected the development of karst in eastern Qinghai.The atmospheric precipitation in the process of rock weathering soil was sequestered in the weathered soil.Due to the extremely low clay permeability,the capillary force between clay minerals prevented the direct displacement of subsequent atmospheric precipitation,which retained part of the infor-mation of atmospheric precipitation at that time.17 groups of weathered soil samples were collected in the karst development area of eastern Qinghai province,and the water sequestered by the weatherd soil was ex-tracted by using the vacuum-low temperature water sample extraction device.According to the temperature effect of hydrogen and oxygen stable isotopes,calculate the temperature of each geological history period was calculated and the temperature change curve was constructed.According to the precipitation effect of hydrogen and oxygen stable isotopes,the rainfall of each geological historical period was qualitatively eva-luated by δD value,and the rainfall change curve was constructed.The results show that the water seques-tered by weathered soilhas a unified source and is affected by evaporation and oxygen isotope exchange;from Proterozoic to Cenozoic,temperature and rainfall fluctuated,alternating between hot and cold,dry and wet;Proterozoic and Paleozoic karst are not developed,and the Mesozoic karst is not fully developed;the Cenozoic is the period of rapid uplift of Qinghai-Xizang Plateau and the main period of karst development in eastern Qinghai.Du-ring the Cenozoic era,the eastern part of Qinghai gradually became cold,and the karst development mode at each stage was different,from chemical dissolution to physical weathering.The overall rainfall was not large,the hydro-dynamic conditions were insufficient,and the intensity and depth of karst development were not large.Therefore,the karst morphology in eastern Qinghai was mainly small karst caves and water inrush karst fissures.
weathered soilsequestered waterisotopekarst developmentuplift of Qinghai-Xizang Plateau
国家科技期刊平台
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