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.

Seismic methods in mineral exploration and mine planning: A general overview of past and present case histories and a look into the future

“…After processing, the migrated seismic profiles were integrated with pipe models, using all available information, to honor geologic data from boreholes (pierce points). Examples of successful downhole imaging for exploration and mine planning are provided by Mueller et al (2012) and Wood et al (2012), respectively. For example, Wood et al (2012) show how steeply dipping reflections from faults can be mapped closer to the surface on VSP data than on surface seismic data, an important outcome that was critically important for mine planning at the Millennium uranium deposit, northern Saskatchewan, Canada.…”

“…Examples of successful downhole imaging for exploration and mine planning are provided by Mueller et al (2012) and Wood et al (2012), respectively. For example, Wood et al (2012) show how steeply dipping reflections from faults can be mapped closer to the surface on VSP data than on surface seismic data, an important outcome that was critically important for mine planning at the Millennium uranium deposit, northern Saskatchewan, Canada. Urosevic and Evans (1998) use a combination of surface and downhole seismic reflection techniques to characterize a thin kimberlite pipe in the Northern Territory, Australia.…”

“…Seismic methods are well-suited to exploration in this setting as the uranium deposits typically occur near the unconformity that separates an undeformed clastic sequence from underlying metamorphic crystalline basement rocks. As summarized by Hajnal et al (2010), the first successful demonstration of high-resolution seismic methods during the Lithoprobe project spawned several subsequent 2D exploration surveys at Shea Creek in 1997, McArthur River in 2004 (e.g., Gyorfi et al, 2007;, Russell and Moore Lake in , and Midwest Northeast and Millennium 3D surveys in 2007(e.g., Juhojuntti et al, 2012Wood et al, 2012). Hathor Resources performed the first seismic-based major uranium discovery in 2007, leading to a 2010 total resource of 12.1 million pounds of U 3 O 8 .…”

3D seismic survey at the Millennium uranium deposit, Saskatchewan, Canada: Mapping depth to basement and imaging post-Athabasca structure near the orebody

“…The faults also can be observed in the migrated depth section along crossline 1280 (Figure 11), from which it appears that the blocks to the north of the faults have moved upward relative to the southern blocks, the estimated maximum throw being roughly 50 m. These interpreted faults are close to the proposed mine shaft locations and could thus be of interest from an engineering perspective. A more detailed discussion of the faults can be found in Wood et al (2012).…”

Integrated interpretation of 3D seismic data to enhance the detection of the gold‐bearing reef: Mponeng Gold mine, Witwatersrand Basin (South Africa)

“…; Urosevic, Bhat, and Grochau ; White and Kjarsgaard ; Wood et al . ; Kukkonen et al . ; Juhojuntti et al .…”