Hydrogeochemical Characteristics And Genetic Of Geothermal Water In Jiangda,Tibet

Geothermal resources are characterized by clean,low carbon,wide distribution,abundant,environmental protection,high efficiency and diverse USES.For Tibet,which has a harsh climate and a lack of energy,exploiting its unique geothermal advantages is expected to break the bottleneck of development and improve people's living conditions.In addition,the site selection and construction of major projects are also faced with the energy demand and the heat damage.Therefore,it is of vital importance to clarify the geothermal distribution characteristics and genetic mechanism in this area.Jiangda County is located in Qamdo,eastern Tibet.The geothermal resources in this area are abundant,but the degree of exploitation and utilization has been low for a long time.This paper selects the typical geothermal display area in Jiangda County as the research object.Collected the basic data of geology,hydrogeology,geothermal geology and so on.Adopted hydrogeochemical research methods,isotope analysis and other comprehensive means to study the hydrochemical characteristics,geothermal fluid material sources,heat storage characteristics and recharge mechanism of typical geothermal display areas in Jiangda County.Reached the following conclusions:(1)The water temperature of the typical hot spring in Jiangda County is between31?and 58?.The spring water has moderate total dissolved solids content and is weakly acidic.The chemical type of Gasi Spring is SO₄²⁺-Ca²⁺,Dengkebalong Spring is HCO₃^--Na⁺·Ca²⁺and Jueyong Sping is HCO₃^--Na⁺,HCO₃^-·Cl^--Na⁺.The thermal reservoir has good hydrodynamic conditions and contacts with the outside closely.The chemical components dissolved in hot spring mainly come from rock weathering dissolution.(2)The hot spring in the study area is mainly replenished by atmospheric precipitation,and is affected by the mixing of shallow cold water to different degrees,resulting in the decrease of water temperature when it is exposed to the surface.(3)Used the silica geothermal thermometer,cationic geothermal thermometer,silicon-enthalpy and chlorine-enthalpy mixed model to estimate the deep heat storage temperature of typical hot spring sites in the study area.The results of the chlorine-enthalpy mixing model are most consistent with the reality.The deep heat storage temperature in the study area is 111?140?,and the mixing ratio of cold water is 10%?25%.The depth of the thermal cycle is about 3059?3887m.(4)The formation of hot springs in the study area is strictly controlled by fracturesandbelongstolowmedium temperature geothermal systems of convective type with deep circulation.