Geological Characteristics And Formation Mechanism Of Geothermal Resources In Huanglin Area,Yudu,Jiangxi

In terms of geological structure,Yudu County is located at the intersection of Taoshan-Yushan Uplift,Ning(Du)Yu(Du)Depression and South Wuyi Uplift in the southeast orogenic belt of the South China Orogenic System.The area has strong structural deformation,developed folds and faults,and geothermal The resources are relatively abundant.Predecessors have carried out related research on basic geology and mineral geology,but due to the complicated geological conditions,they failed to clarify the deep thermal storage structure and genetic mechanism,which severely restricted the development and utilization of geothermal resources in this area.This research takes Huanglin typical geothermal area as the research object.Based on the field geological survey,high-density electrical exploration,controllable source audio magnetotelluric sounding,combined with depth and shallowness,analyzes the change law of underground resistivity,and clarifies the geology of the study area.Structural features.Through the full analysis of geothermal fluid water quality,stable isotope research,geothermal temperature scale and silicon-enthalpy model,explain the origin of geothermal water from the perspective of hydrogeochemistry.Finally,the geological characteristics and formation mechanism of the geothermal resources in the study area are revealed from the source,channel,reservoir and cover.The research mainly draws the following conclusions.1.Basically find out the geological structure and underground distribution of the study area to provide a basis for the determination of the geothermal exploration target area.The high-density electrical method and the controllable source audio frequency magnetotelluric sounding inversion interpretation results show that the fractured zone in the study area shows obvious low-resistance anomalies due to water content,while the surrounding rock mass resistivity is relatively high.This resistivity change law is An important basis for analyzing the deep development characteristics of faults in the study area and the distribution range of heat storage.NE is towards Anyuan-Yingtan deep fault,trending NE40°,inclined to SE,with an inclination of about 60°.The fault scale is large,with a bandwidth of up to 100 meters.It is the main heat-controlling and water-storing structure.The NNE-trending fault strikes NE10°,tends to be SE,and the occurrence is almost upright.The analysis shows that the two groups of fault interaction zones are favorable locations for the occurrence of geothermal water.2.Basically clarify the chemical properties of geothermal water,and provide hydrogeochemical basis for explaining the mechanism of geothermal formation in the study area.(1)The water chemistry data shows that the surface water body with dew point is mainly HCO₃-Na·Ca and SO₄·HCO₃-Na·Ca type water.The deep geothermal water has a long circulation path and strong water-rock interaction,which has not yet reached equilibrium,has high retention characteristics,and presents a phenomenon of cold water mixing.(2)Hydrogen and oxygen isotope analysis shows that surface water and shallow groundwater in the study area are greatly affected by atmospheric precipitation,and the oxygen isotope of some hot water spots drifts,indicating that geothermal water experiences strong water-rock reactions,and the main source of replenishment is atmospheric precipitation.(3)The calculation of geothermal temperature scale shows that the calculation results of different temperature scales are quite different.The quartz temperature scale and chalcedony temperature scale without steam loss may re-reach the equilibrium state of the chemical reaction during the rising process of the hot water,and the estimated heat storage temperature is significantly lower.3.Basically clarify the formation mechanism of geothermal in the study area,and provide a basis for the rational development and utilization of geothermal resources in the study area.Based on the analysis of geological data and borehole data,a conceptual model of the genetic mechanism of geothermal resources in the study area is established.It is considered that the Jiangxi Huanglin geothermal field belongs to a fault-convection deep-cycle geothermal system.The new understanding of the"ternary heat generation model"of heat and radioactive heat generation in fluorite mines provides theoretical basis for the promotion of future geothermal exploration and scientific utilization of geothermal resources in the study area,and helps the central old area to fight poverty.