An interpretation of surface and borehole seismic surveys for mine planning at the Millennium uranium deposit, northern Saskatchewan, Canada

Abstract

The Millennium uranium deposit is located within the Athabasca Basin, in northern Saskatchewan, Canada. The deposit is hosted within moderately dipping Paleoproterozoic gneisses that are unconformably overlain by more than 500 m of flat lying, porous Paleoproterozoic to late Mesoproterozoic Athabasca Group sandstones. The deposit is associated with the sandstone-basement unconformity, post-Athabasca structure, and hydrothermal alteration. These features combine to create a complex 3D hydrogeologic setting that presents challenges with respect to mine development, production, and safety. In 2007, as part of a prefeasibility study for potential mine development, a seismic program consisting of a 3D surface survey, vertical seismic profiling, moving source profiling, and side-scan surveys was undertaken to map the complex geology. The geometry and resolution of these different seismic surveys allowed for direct imaging of the geologic targets of interest, regardless of orientation and size. After integration with drill-defined geology, the program successfully imaged the location and character of the unconformity, the post-Athabasca structural setting at camp and deposit scales, and the alteration around the deposit. This information increased the understanding of geotechnical aspects of the geology hosting the deposit, and is currently being used to help minimize risk and costs associated with mine development. Seismic surveys are now viewed as an integral part of risk reduction associated with mining in the Athabasca Basin.