The high-grade unconformity-related uranium deposits in the Athabasca Basin in northern Saskatchewan, Canada, generally show close spatial relationships with reactivated basement faults. However, the nature of this relationship has not been well understood. This thesis aims to address this problem through two interrelated components of research. The first phase of the research involved 3-dimensional (3D) geometric modelling of the unconformity surface in the southeastern Athabasca Basin, in conjunction with basement structures interpreted from regional-scale geophysical data. The second phase was accomplished through 2-dimensional (2D) numerical modelling of fluid flow involving basement faults, with thermal convection and faulting-related deformation as the driving forces, respectively. The detailed 3D model of the sub-Athabasca unconformity surface, constructed from drill hole data with GoCAD, reveals numerous dominantly NE-trending ridges and valleys in the unconformity surface. The most prominent ridge, up to 320 m high and extending northeast semi-continuously from the Key Lake deposit in the south to McArthur River deposit in the north, is interpreted to result from displacement along a major basement fault zone. It coincides with a regional, northeast-trending alteration corridor that hosts several large uranium deposits and a number of prospects. Numerical modelling of free thermal convection involving basement faults using FLAC3D indicates that the location, spacing, orientation and thermal conductivities of basement faults exert influence on the size and location of the convection cells. For models with an isolated basement fault zone, an up-flow centre coincides with the fault zone and the dip angle of the fault zone does not affect the fluid flow pattern. In the case of two fault zones, however, the upwelling plume between two convection cells may either coincide with each fault zone or be located between the two fault zones, depending on fault spacing. When the permeability of the basement is less than two orders of magnitude lower than that of the overlying sandstone, the basement faults can act as fluid conduits of either ingress or egress flow, depending on their thermal conductivities and relative locations in the models. Numerical modelling of fluid flow in relation to deformation in a compressional stress regime indicates that the fluid flow pattern is sensitive to the degree of bulk shortening. At a low bulk shortening stage, fluid is driven up along the fault zone into the sandstone in the basin, whereas at a relatively high degree of bulk shortening, fluid tends to flow down into the fault zone and the basement. The results demonstrate that varying the dip angle and pre-existing offset along the fault has a negligible effect on the strain distribution and fluid flow patterns. These modelling results imply that both sandstone-hosted and basement-hosted orebodies may be generated at different stages of deformation within the same fault system under a unified compressional stress regime. The results of this research confirm the importance of pre-existing basement faults in the formation of unconformity-related uranium deposits in the Athabasca Basin. The fluid circulation in the basin and basement may be characterized by the dominance of thermally-driven fluid convection during periods of tectonic quiescence, and by deformation-driven fluid flow during relatively active periods, perhaps related to far-field tectonic events. Keywords: 3D modelling, numerical modelling, fault interpretation, thermal convection, fault reactivation, fluid flow, unconformity, uranium deposit, Athabasca Basin