Geological And Geochemical Characteristics Of Tang Yang Geothermal Anomalies Area In Zhang Zhou,Fu Jian Province

Geothermal anomalies exist in Tangyang area in southeastern Ganzhou,and there are few studies on geothermal resources in the area.This paper relies on the Fujian196 Geological Team project of“Pre-feasibility exploration plan for geothermal resources in Tangyang Mining Area of Economic and Technological Development Zone of Zhangzhou Investment Promotion Bureau of Fujian Province”.According to the geological structure and hydrogeological conditions of the study area,the chemical characteristics of geothermal fluids in geothermal drilling and the radioactive characteristics of granite,the paper provides a reliable theoretical basis for the subsequent rational development and utilization of local geothermal resources.In this paper,combined with geothermal exploration project in the study area,field survey,geophysical survey,water sample analysis and granite sample test were carried out.The geological and hydrogeological conditions in the study area were analyzed,and the temperature and water of underground hot water in Tangyang area were studied.The chemical properties of the granite bodies in the study area were calculated and their heat generation contributions were calculated.The study area is located in the marginal zone of the Pacific plate subduction to the Eurasian plate.It has experienced many large-scale tectonic activities and magmatic activities.Below the study area is granite body of Yanshan period,magma waste heat,deep heat source and the radioactive element decay heat energy of the granite body are good heat sources.The geothermal anomaly in the study area shows that the shallow ground temperature is higher than the normal groundwater temperature,and the geothermal gradient of the heat storage part is 4.17°C/100 m,which is higher than the normal geothermal gradient.The underground hot water belongs to the low salinity HCO₃-Ca·Na type water,and has the effect of fluorine treatment,and has the characteristics of non-corrosive and non-fouling.At the same time,based on the stable isotope D?²H?,¹⁸O,the underground hot water in the study area was derived from atmospheric precipitation.According to the calculation of radioactive heat generation,the average radiothermal heat generation rate of geothermal bored granite in the study area is3.23?W/m³,which is 1.3 times of the heat generation rate of granite in the world.The average contribution rate of U elements is 33.61%,the average contribution rate of Th elements is 53.39%,and the average contribution rate of K elements is 12.99%.The contribution rate of radioactive heat flow accounts for 47.54%of surface heat flow,which show radioactive heat generation is an important part of the surface heat flow.