Isotopic And Hydrogeochemical Evidence Of Remaining Sedimentary Water In The Deep Geothermal Reservoir Of Guanzhong Basin

There are abundant geothermal water resources in the deep of Guanzhong Basin, which as a low carbon green new energy can greatly reduce environmental pollution and can effectively control the haze with the economic development time. What kind of water the deep geothermal water in Guanzhong Basin belongs to, whether residual sedimentary water is, whether sustainable development and utilization can, have always been the focus of academic circles and government functional departments.This article focuses on the deep geothermal water in Guanzhong Basin and applies a variety of environmental isotope and hydrogeochemical methods combined with the sedimentary evolution of Guanzhong Basin to demonstrate whether residual sedimentary water in different tectonic units of Guanzhong Basin exists and to provide the relevant evidence that there is residual sedimentary water in Guanzhong Basin.The Guanzhong Basin is a lacustrine facies sedimentary basin, the δ values(δD and δ18O)of deep geothermal water have a drift and the δ values of part samples fall within the range of δ values of sedimentary water. In which, geothermal water of Huayin in Gushi depression have high TDS and belong to Cl-Na·Ca type, whose d-excess is as low as-41‰. In addition, its degree of desulfurization is high and thermal storage environment is closed, which is coincidence with the hydrochemical characteristics of continental sedimentary water. The R/Ra values of all samples are less than 1, indicating that geothermal water of Guanzhong Basin is not from mantle. The evidences of 14 C age, δ13C and δ18O confirm the geothermal water in the study area may be formed in the long geological time. The features of δ11B indicate the deep geothermal water in Guanzhong Basin originates from nonmarine evaporate and it provides the evidence that there may be residual sedimentary water in study area.The results of 36 Cl age show that the biggest age of deep groundwater of Guanzhong Basin is 1051.09 ka. Geothermal water with different tectonic units, different closed condition and different genetic types has different 36 Cl age. In which, the 36 Cl age of Wenre 4 and Weire 4 are 1051.09 ka and 737.58 ka, respectively, to a certain extent, they represent the age of geothermal water in Xianli terrace and Gushi depression, and they provide the evidence of 36 Cl age that there is residual sedimentary water in Guanzhong Basin.Although geothermal water of these two sample points is still the mixture of infiltrating water in different periods and different degrees, in consideration of their relatively closed thermal storage environment, they still retain the age characteristics of residual sedimentary water formed in geological time. It estimates that the age of original sedimentary water in Guanzhong Basin should be around one million years, which belongs to can not update of precious natural resources...