Bridging the 39Ar–14C Groundwater Dating Gap: A Dual-Permeability Transport Perspective Based on Numerical Modeling and Field Data - Dataset

This dataset supports the study titled ''Bridging the 39Ar–14C Groundwater Dating Gap: A Dual-Permeability Transport Perspective Based on Numerical Modeling and Field Data'' and contains the HydroGeoSphere (HGS) input files used to simulate reactive tracer transport in a reference dual-permeability groundwater model. The model was developed to investigate mechanisms driving discrepancies between apparent groundwater ages derived from Argon-39 and Carbon-14 tracers—particularly in systems where diffusive exchange and in situ underground production significantly bias the apparent tracer ages. The domain consists of a vertical fracture embedded in a low-permeability porous matrix, explicitly representing physical processes such as advection in the fracture, diffusion into and from the matrix, longitudinal dispersion, and depth-dependent production of 39Ar. Boundary and initial conditions were configured to simulate long-term transient flow over 20,000 years, allowing tracer activity to equilibrate under realistic hydrogeological conditions. This reference model forms the basis for a broader sensitivity analysis assessing the impact of fracture aperture, porosity, diffusion coefficients, and dispersivity. The dataset supports reproducibility of key numerical results and provides a framework for future groundwater age-dating studies using HGS in complex fractured media.