Karst geothermal systems hold enormous potential for geothermal exploitation.The Maxing and Gepi geothermal anomaly areas are typical geothermal fields in Longmen County,Guangdong Province.The temperature and fluid evolution of geothermal reservoir can be clarified,with the analysis of ion ratio relationship,δD and δ18O isotopes,and geothermal thermometers et.al.It is indicated that silicate minerals,carbonate minerals such as calcite dissolution,and accompanying cation exchange control the hydrochemistry evolution,thus forming slightly alkaline HCO3-type geothermal water with lower TDS in the study area.The results suggest that atmospheric precipitation is the main recharge source.The reservoir temperature is 105.0-148.0℃and 101.5-131.0℃for Maxing and Gepi geothermal reservoir respectively,with a lower temperature during upwelling caused by mixing with cold water up to 44.2%and 48.5%dilution.In this case,a conceptual model for geothermal fluid evolution is proposed based on the geothermal water hydrochemistry and reservoir temperature characteristics.
karst geothermal waterhydrochemistrygeothermal reservoir temperatureconceptual modelgeothermal energy
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