Proposed Title 1: - Queen's University

during brecciation or reduction as the U-mineralizing fluid reacted with reducing
metamorphic host rocks (e.g. Skirrow et al., 2009).
Strong structural control is reported in most metamorphic-related U systems, with U
originating from saline, F-rich and CO 2 -bearing, Na-Ca brines (Skirrow et al., 2009) and
commonly hosted by reactivated fault zones (Cuney and Kyser, 2008). In the Beaverlodge
area, the high δ 18 O values of metamorphic fluids reflect the low water/rock ratios, and
hence the relatively low volume of fluid, during hydrothermal alteration, preventing the
transport of enough U by metamorphic brines to produce economically significant U
mineralization. This is consistent with Plant et al. (1999) suggestion that U deposits of
metamorphic-dehydration origin are of low grade and tonnage. The Beaverlodge U deposits
are similar to metamorphic-related U mineralization systems associated with Nametasomatism
(Cuney and Kyser, 2008) and related to the global 1.9-1.75 Ga alkalimetasomatism
(Cuney, 2010).
5.2.2. Successor basin-related U mineralization
5.2.2.1. Volcanic-related U mineralization
Volcanic-related U mineralization in the Beaverlodge area was triggered by extrusion
of the 1818±4 Ma alkaline mafic dikes (Morelli et al., 2009) during deposition of the
Martin Lake Basin (Langford, 1981; Mazimhaka and Hendry, 1984). Extrusion of the mafic
dikes is coincident with periods of active tectonism related to back-arc extension following
peak Trans-Hudson Orogen (Hoffman, 1989; Corrigan, 2009). The δ 18 O, δ 13 C and δ 2 H
values and chlorite crystal chemistry of syn-ore minerals indicate that the U mineralization
formed at ca. 1820 Ma from ca. 320°C, Mg- and Fe-rich magmatic fluids that were likely
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