Matrix permeability testing in the fault-hosted Gryphon U deposit (eastern Athabasca Basin, Canada): Insights into fluid-rock interactions related to deposit formation and redistribution

As a demonstration of the utility of testing permeability of rocks, in this study the matrix permeability was tested across a wide fault zone in Precambrian metasedimentary rocks at the basement-hosted Gryphon uranium deposit. It is part of the Wheeler River project by Denison Mines in Athabasca Basin, Saskatchewan, Canada.The permeability tests were done on unconfined dry uncut drill core pieces (4.7 to 6.1 cm diameter), sampled from inclined exploration drill holes. A portable nitrogen gas probe permeameter device was constructed and adapted for testing spots on whole drill core pieces. The device features a stiff aluminum metal frame and can hold a variety of drill core sizes. A pressure-decay method was used, with initial gas pressure charged to about 50 psi (pounds per square inch), equivalent to approximately 0.345 MPa, charged from an external tank, and an intermediate container.793 tests had good quality results of 900 attempted tests. In the failed (rejected) tests, a small leak occurred in about 5% of the samples, and a large leak in another 5%. In basement lithologies 666 tests were successful.<br><br>