Geology Talk

Wed., Mar. 20, 2019 4:00 p.m. - Wed., Mar. 20, 2019 5:00 p.m.

Location: Classroom Building 130

Presenter: Mr. Arin Kitchen, MSc. Student in the Department of Geology at the University of Regina

Topic: Nature and context of deformation bands associated with post-depositional faulting of the basal Athabasca Basin

Abstract: In northern Saskatchewan, world-class uranium deposits are associated with the unconformity between the Proterozoic Athabasca Basin and underlying basement rocks. In particular, many of the uranium deposits exhibit a strong spatial association with post-Athabasca faults formed by reactivation of older basement-rooted structures. The focus of this study is deformation bands in the basal Manitou Falls Group. Deformation bands are products of localized strain, resembling micro-faults; they develop in highly porous sediments and are associated with fault damage zones. Deformation band formation can result in a change in porosity due to grain rotation and granular flow which gives them the potential to act as fluid baffles or conduits. In this study deformation bands were investigated in sandstones of the basal Manitou Falls Group in five drill-hole fences transecting the C1 fault, a mineralized NNE-trending structure extending from the Gryphon deposit to 5km west of the MacArthur River deposit. Our results indicate that compaction, shear, and cataclastic bands are present throughout the core and that the proportion of cataclastic bands increases with depth. Collectively, all bands define three major trends; one subhorizontal (286°/11°), and two which appear to share a conjugate relationship, (074°/57°) and (324°/65°). The derived paleostress field is incompatible with the orientation of the (020°/50°) C1 fault, which records significant reverse/thrust displacement. The fault zone may therefore have been reactivated after Athabasca Group sandstone deposition under a new stress regime (inferred from the orientation of the deformation bands). Alteration products related to mineralization were also observed; drusy quartz veins exhibit the same conjugate relationship as the general population of deformation bands, whereas dravite veins preferentially occur along the northeast trend. Further work aims to improve the understanding of deformation band genesis in relation to post-depositional fault reactivation, and the role these structures have in fluid movement associated with uranium mineralization.

Co-Authors: K. Bethune, Department of Geology, University of Regina, Regina, Saskatchewan; G. Delaney, Saskatchewan Geological Survey, Saskatchewan Ministry of Energy and Resources
Saskatchewan, Regina, Saskatchewan; E. Miller, Department of Geology, University of Regina, Regina, Saskatchewan.