Formation Mechanisms and Hydrogeochemical Evolution of a Metasilicate-Strontium Rich Mineral Water in a Subtropical Volcanic Terrain, East China

Natural mineral waters hosted in volcanic terrains are globally significant, but the co-enrichment mechanisms of metasilicate and strontium remain poorly understood. Here we investigate a Jurassic volcanic-hosted mineral water source in eastern China using hydrochemical analysis, 14C dating, stable isotopes, and structural analysis. The groundwater is of Ca–Mg–HCO3 type with slightly alkaline pH (7.44–7.63). Metasilicate (26.4–32.9 mg/L) and strontium (0.40–0.83 mg/L) co-enrichment is governed by plagioclase weathering in a bicarbonate-dominated, weakly alkaline environment where SrHCO3+ ion pairs enhance strontium mobility. Pearson-corrected 14C ages of 3900–4900 years reveal that millennial-scale residence time is critical for sufficient water-rock interaction and attainment of regulatory thresholds. A conduit-barrier system formed by NW-trending extensional-shear and NNE-trending compressional-shear faults controls groundwater flow paths and residence times, leading to systematic inter-well hydrochemical differentiation. These findings provide a theoretical basis for the genetic identification, potential evaluation, and sustainable management of high-quality mineral water resources in volcanic terrains.