Proposed Title 1: - Queen's University

Figure 5.3. Schematic illustration of the tectonic evolution of the Main Ore Shear Zone and
the Saint Louis Fault on a crustal scale showing the spatial distribution of breccias, cataclasite
and mylonite. A: Mylonitisation with oblique-normal and lateral dextral sense of motion in
the ductile environment. B: Cataclasite overprinted the ductile shear zones subsequent to
exhumation of the fault zone to shallower crustal depths. C: Breccias formed during
reactivation the ductile-brittle fault zone in the brittle environment presumably at near
surface conditions.
These fluids were likely derived from dehydration of hydrous minerals and ascended
upward along fracture systems and dilatant jogs that resulted from brittle reactivation of
early shear zones (Fig. 5.3), thus providing pathways for metamorphic fluids that
scavenged and transported U-bearing fluids (Fig. 5.1). Uranium precipitation in the breccia
system was likely caused by a decrease in the solubility of the U-carbonate complexes
resulting from a loss of CO 2 and a decrease in temperature caused by fluid decompression
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