Indicating Meaning Of Isotope Evolution About The Genetic Classification Of Geothermal Water In Gu Shi Depression And Hydraulic Conductivity Of Weihe Fault

Isotope and geochemistry techniques have an irreplaceable advantage in studying the supply sources, causes and classification of geothermal water. Based on field survey and field sampling isotope analysis, this paper systematically studies the characteristics of Gushi depression geothermal water and the Weihe fault Mechanism of water. The research can enrich geothermal water deep cycle theory and provide a scientific basic for the development and utilization of geothermal resources in the Gushi depression and Xi’an-Xianyang Guanzhong Urban Group.δD and δ18O of geothermal water in Gushi depression show that: different geothermal water of Gushi Depression has different occurrence characteristics and supply source. 13 C of geothermal water show HCO3- is not source of gas or mantle but dissolving from carbonates dissolution. The relationship of δ13C vs HCO3- indicates that according to environment closed degree, geothermal water can be divided into Gushi sub-sag > Erhua fault terrace> Sanyuan fault terrace. δ34S reveals geothermal water in Gushi depression may be experienced from open state of atmospheric precipitation to closed state of retaining process. Geochemical characteristics of geothermal water in Gushi depression show that geothermal water is generally influenced by the action of leaching, mixing, decarboxylation, ion exchange, TDS of geothermal water in Gushi depression is the highest. The evolution of isotopic and hydrogeochemical characteristics reveal that geothermal water in Sanyuan fault terrace supply from Northeasterly Miao mountain, geothermal water in Erhua fault terrace main recharge from ancient precipitation of southwest Shaohua mountain, geothermal water in Gushi depression is sedimentary water or residual sedimentary water which is formed with Guanzhong basin.Hydrogeochemical characteristics of geothermal water along the fault strike from west to east turn SO4-Na into Cl-Na, and TDS gradually increased, combined with the result of deuterium oxygen and strontium isotopes, Weihe fault has the hydraulic conductivity along the fault strike. Geothermal water in the north and south of Weihe fault has different characteristics of hydrogeochemical type, oxygen and deuterium isotope enrichment, strontium isotope content and residence time, suggesting a relatively impermeable in the vertical of Weihe fault. Geothermal water near Weihe fault compared to non-fault nearby geothermal water has higher temperature and cycle depth, oxygen and deuterium isotope study show that geothermal water near Weihe fault has mixed with local confined water, indicating Weihe fault has conductivity in the vertical. In summary, Weihe fault have a profound effect on the formed and occurrence of geothermal water in the abdomen of Guanzhong basin.