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Beaverlodge area (Morelli et al., 2009) (Fig. 2.15). These ages are identical to an 1827±4
Ma age (Bostock and Breemen, 1992) obtained for the southeast-east-southeast-striking
Sparrow diabase dike swarms, which span the boundary between the Taltson Magmatic
Zone and the western Churchill province (Fig. 2.14). These dates are also similar to the
1800 Ma age that Russel and Ahren (1957) reported for the west orebody of the Ace
deposit (Fig. 2.2). The U-Pb upper intercept ages of 1783±7 Ma and 1774±25 Ma (Figs.
11D and 11E) are identical to the 1780±20 Ma date that Koeppel (1969) originally
interpreted as the age of vein-type uranium deposits in the Beaverlodge area. However,
these ages are likely related to a post-mineralization alteration and resetting event
associated with fault reactivation during the emplacement of the 1788±3 Ma (Ashton et al.,
2009b) northeast-striking, post-orogenic, lamprophyre and granitic dikes (Sassano et al.,
1974; Ashton et al., 2006) that cut the Uranium City mafic dikes (Tremblay, 1972).
Sassano et al. (1974) suggested that the lamprophyre dikes are associated with the latekinematic
phase of the Trans-Hudson Orogen, at which time the uplift of the northwest
Churchill province took place.
Late east-west compressional regime associated with tectonic readjustments during
terminal ca. 1.81-1.69 Ga post-collisional convergence in the Trans-Hudson Orogen (e.g.
Hajnal et al., 1996; Chiarenzelli et al., 1998) caused folding of the Murmac Bay Group and
Martin Lake Basin rocks (Ashton et al., 2009a), followed by uplift, erosion, thermal
relaxation, subsidence, and deposition of the Athabasca Basin at ca. 1750 Ma (Kyser et al.,
2000) (Fig. 2.13G). Late brittle reactivation along fault zones during the Mesoproterozoic
caused minor fracturing and deposition of U 6 uranium mineralization related to fluids likely
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