江西新泉—温汤断裂东段中低温地热流体水化学特征及成因机制OA

The eastern segment of the Xinquan-Wentang Fault Zone in Jiangxi Province hosts abundant mid-low temperature geothermal resources.However,research on the genetic mechanism of its geothermal fluids remains relatively scarce,which hinders the scientific development of hydrothermal resources in this area.This study focuses on the geothermal fluids in the eastern part of the Xinquan-Wentang Fault Zone.By integrating hydrogeochemical methods and multi-isotope(H-O-Sr-C)tracing techniques,we identify the hydrochemical circulation and evolutionary processes of the geothermal water and elucidate the genetic mechanism of the geothermal resources.The results show that the geothermal water in the study area exhibits a temperature range of 23.1-40.5℃,weak alkalinity(pH:8.20-8.94),and low total dissolved solids(TDS:135.0-225.2 mg/L),with a HCO3-Na hydrochemical type.Molar ratios of major solutes,Sr isotopic compositions,and hydrogeochemical modeling demonstrated that silicate mineral dissolution dominated the hydrochemical evolution,followed by cation exchange.Hydrogen-oxygen isotopic signatures and radiocarbon(14C)dating revealed that the geothermal waters in the region originated from paleo-atmospheric precipitation at approximately 4 kaBP,with the recharge areas being located in the Wugong Mountain area southwest of the study region(at elevation of 719-1 104 m).Integrated multicomponent solute geothermometry revealed reservoir temperatures of 74.2-115.5℃and circulation depths of 1 660.0-2 881.9 m,with a mixing ratio of shallow cold water ranging from 71.1%to 76.2%.The genetic mechanism of geothermal water involved atmospheric precipitation infiltrating downward through granite-weathering fractures into deep reservoirs,where it was heated by crustal thermal sources.Subsequently,driven by buoyancy forces resulting from density variations,the heated fluid ascended rapidly along the major fault zones and discharges into the valley,due to topographic incision,forming the present hydrothermal geothermal resources in the region.These findings not only clarify the migration and enrichment mechanisms of geothermal fluids in fault-controlled geothermal systems but also provide critical theoretical support for regional geothermal exploration and sustainable utilization.