Formation of the unconformity-related uranium deposits in the Athabasca Basin, Canada: insights from hydrodynamic modelling

The unconformity-related uranium deposits in the Athabasca Basin, Canada, are generally associated with reactivated basement faults crosscutting the basin basement unconformity with variable reverse displacements. The fluid flow related to uranium mineralization may be driven by thermal convection and/or tectonic deformation; however, little is known regarding exactly how basement faults influence convection, how basement faults may affect fluid flow during compressional deformation, and the interrelationship between thermal convection and compression. These questions are addressed through numerical simulations with various configurations of basement faults using FLAC3D software. Modelling undertaken with thermal convection only indicates that during periods of tectonic quiescence, basement faults with elevated permeabilities and thermal conductivities affect fluid convection cells in the basin. Fluid may flow into one fault, out of another fault, or into and out the same fault, potentially forming ingress, egress, and hybrid styles of mineralization. The modelling related to compressional deformation only suggests that sandstone- and basement hosted deposits may be generated at different stages of deformation within the same fault system, depending on the degree of the compression. In addition, the strain rate controls the interaction between thermal convection and deformation-driven fluid flow.