Coupled hydrogeological and geochemical processes and structural controls on geothermal systems in Odisha, India
摘要
Geothermal springs in the Mahanadi region represent a low to moderate enthalpy geothermal system with potential for sustainable energy utilization. Integrated hydrogeochemical, geophysical, and geological investigations indicate that water–rock interaction, ion exchange, and structurally controlled fluid circulation govern the system evolution, with the fracture network acting as the primary control on regional fluid migration. Thermal waters are classified as Na–Cl and Ca–Mg–HCO₃ types, whereas non-thermal waters are Ca–HCO₃ type, reflecting limited mixing and meteoric recharge dominance. Elevated Na⁺/Cl⁻ ratios suggest that sodium enrichment in groundwater is mainly controlled by silicate weathering reactions, especially feldspar dissolution, reflecting dominant water–rock interaction processes with minimal marine influence. Key scaling phases include calcite, dolomite, gypsum, and anhydrite, with carbonate precipitation in near surface discharge zones driven by CO₂ degassing, induced supersaturation, leading to active scaling and mineral deposition.
VLF-EM surveys delineate conductive fracture networks extending to depths, highlighting structurally controlled pathways for geothermal fluid migration. The estimated average reservoir temperature is