| Xiong’an New Area is one of the areas with the best conditions for geothermal exploitation and utilization in the middle and east of China with a history of more than 20years.The study of geothermal origin in Xiong`an New Area plays an important guiding role in the exploration and development of geothermal resources.Deep geothermal fluid in the process of migration to carry a lot of information about the source,channel and thermal reservoir.Therefore,this paper focused on hydrogeochemistry of geothermal waters from the Guantao Formation and the Wumishan Formation in Xiong`an New Area.By hydrochemistry method,isotope technology,geothermometers,combined with geological and geothermal geological background analysis,the thermal reservoir genetic model is established from the perspectives of source,access,cap and reservoir,providing theoretical support for the subsequent exploration and exploitation of geothermal resources in this area.The main understanding is as follows:（1）There are obvious differences in hydrogeochemical characteristics of geothermal water in different thermal reservoirs in Xiong`an New Area.The main ions of Guantao geothermal reservoirs are Na+,Cl-and HCO3-,and the main ions of Wumishan geothermal reservoirs are Na+and Cl-.The shallow cold water is mainly HCO3-Ca·Mg type,while the deep geothermal water mainly is Cl·HCO3-Na type,among which the Guantao geothermal reservoirs has various hydrochemical types.The TDS of shallow water is 410-629 mg/L,451-1998 mg/L of Guantao geothermal reservoirs,and 2678-2982 mg/L of Wumishan geothermal reservoirs.The hydrochemical characteristic parameters and concentration characteristics of major components indicate that the geothermal reservoir environment of Wumishan Formation is more closed,the water-rock interaction is more intense,and the runoff is slower.（2）In the infiltration process of geothermal water in the study area,isotope exchange is strong due to warming and other effects,and the"oxygen drift"of underground hot water is obvious,and the calculated recharge elevation of geothermal water in the area is512-1065 m,which coincides with the elevation of Taihang Mountain,and the source of recharge should be atmospheric precipitation in Taihang Mountain;the 14C isotope characteristics of underground hot water indicate that the age of thermal water in the Wuzhishan Group is above 30 ka,while that in the Pavilion Tao Group is between 20-30ka.The 14C isotope characteristics of underground hot water indicate that the age of groundwater in the thermal reservoir of the Wuzhishan Group is above 30 ka,while that of the Tantao Group is between 20 and 30 ka,which also reflects the characteristics of long and slow groundwater runoff in the deep part of the study area.（3）The Na-K-Mg triangle diagram shows that the geothermal water of the Wuzhishan Group is not in equilibrium,and it is not suitable to use the cationic temperature scale to calculate the thermal storage temperature;the geothermal water of the Tantao Group is in partial equilibrium,and the calculation result of the Na-K temperature scale is closer to the measured value.The temperature calculation can be carried out by using chalcedony temperature scale.By taking the average of the geothermal temperature scale results for each thermal storage layer,the thermal storage temperature of the Tantao Group is 52-65℃,and the circulation depth range is 1.1-1.5 km;the thermal storage temperature of the Wuzhishan Group is 68-95℃,and the circulation depth range is 1.6-2.4 km.（4）The internal heat energy of Xiong`an New Area is mainly transferred by heat conduction between rock layers and heat convection in the thermal reservoir.The mode of the genesis of the middle and deep thermal storage is that the atmospheric precipitation in the Taihang Mountains is infiltrated through the fractures in front of the mountains,and is heated by the radiogenic heat of the mantle and the crust during the slow runoff in the deep part,and is transported vertically into the carbonate thermal storage layer of Wuzhishan and the sandstone thermal storage layer of the Tantao Group through the fracture zone of the bulge area,and the heat and water are enriched in the bulge area under the effect of water insulation of the upper Quaternary and Neoproterozoic strata.In addition to the upward recharge of deep hot water,it also receives the recharge of shallow cold water at the fracture;the geothermal water renewal ability of the thermal reservoir of Wuzhishan Group is weak,so the development and utilization should pay more attention to the recharge to avoid a large loss of geothermal water. |
PDF Full Text Request