1. Unconformity-associated Uranium
(known more usually as
unconformity-type uranium)

3. Unconformity–associated prospects of the Thelon Basin are Boomerang Lake (B) and Kiggavik (K). Hornby Bay Basin (HBB) hosts the sandstone-hosted PEC-YUK prospect.

8. Cigar Lake is dominantly unconformity ore with minor basement-hosted lenses and perched ore in the overlying Manitou Falls Formation.

9. Key Lake included both basement-hosted and unconformity ore

10. Eagle Point is mostly basement hosted

11. Diagrammatic explanation of ‘egress’- versus ‘ingress’-style alteration zones for unconformity-associated uranium deposits, after Hoeve and Quirt (1984), Sibbald (1985), Fayek and Kyser (1997), and Quirt (2003). Fluids flowing from the basement were reducing; fluids from the redbeds were oxidizing and contained uranium. Models invoke mixing of such fluids at the unconformity to precipitate uranium. The shear zones and fluid flow along them may have been linked

12. Two end-member ‘egress-type’ sandstone alteration models for uranium deposits in the eastern Athabasca Basin (modified from Matthews et al. ( A) Quartz dissolution egress style (e.g. Cigar Lake, Midwest). B) Silicification egress style (e.g. McArthur River, Key Lake). Cap = secondary black-red earthy hematite capping ore bodies, Reg = regolith profile grading from red hematitic saprolite down through green chloritic alteration to fresh basement gneiss, UC = unconformity, Up-G = upper limit of graphite preserved in footwall alteration zone. Fresh = unaltered metamorphic basement: Fe-Mg-chlorite biotite paragneiss. Note that the silicification is a very early component of the right-hand model, and that quartz dissolution is also present there, albeit a minor localized feature.