洱源地区温泉流体地球化学特征及与地震活动的关系OA

We analyze the geochemical characteristics of five hot spring fluids in Eryuan and its sur-rounding areas,and explore the relationship among geothermal distribution,mantle-derived fluid de-gassing,hydrochemical anomalies,and seismic activity.The results show that hydrochemical type of hot springs in the study area include HCO3·SO4-Na·Ca,HCO3·SO4-Na,HCO3·Cl-Na,SO4-Ca·Na,and SO4·Cl-Na·Ca.The main sources of hot spring gases are atmospheric saturated water and air,with contributions from volatile components in the crust and mantle.The heat storage tem-peratures of hot springs in the study area ranges from 164 to 275 ℃,and circulation depths is from 6 369.78 to 11 143.98 meters.The content of He is from 12.90 to 821.62 ppm.Large-scale deep faults in Eryuan area provide favorable channels for the upward migration of deep-sourced fluids,and the deep-sourced fluids are the direct sources of geothermal energy and He.There is a correlation between the geochemical characteristics of hot spring fluids and seismic activities,which is characterized by the deeper the circulation depth,the higher the geothermal reservoir temperature,and the stronger the seismic activity.Moreover,most of the M≥4 earthquakes are located in the transition zone between high and low geothermal reservoir temperatures.The Cl-and SO42-concentrations of Wenmiao hot spring show abnormal increases before and after earthquakes,mainly due to the contribution of the mixing of deep-sourced fluids and different aquifers.The temperature at spring outlet shows an abnor-mal decrease,which may be related to the fact that multiple fractures provide heat dissipation chan-nels after the earthquake.The hydrochemical values of hot springs were restored after the earthquake,indicating that the deep-sourced fluid activity in Eryuan area weakened.