Proposed Title 1: - Queen's University

deposits is related to fluids derived from diagenetic processes in sandstone of the El
Sherana Group and have particularly affected zones of preexisting weakness of the
basement rocks that were previously altered by a metamorphic pre-ore alteration stage. The
source of U was U-bearing minerals (monazite, apatite) in the sandstone and felsic rocks of
the El Sherana Group. The Au and PGE are derived from basement felsic and mafic rocks,
as proposed by Wyborn et al. (1997). Therefore, these deposits can be classified as
unconformity-related uranium mineralization like those in the younger overlying
Kombolgie Basin.
Results from Stewart (1965) indicate that felsic volcanic rocks of the Pul Pul Rhyolite
of the El Sherana Group have above background radioactivity. Analyses indicate
concentration of up to 25-30 ppm U in these volcanic rocks (Ayers, 1975). Fluid inclusion
data (Mernagh et al., 1994) indicate that the fluids were saline, acidic, calcium-dominated
(ca. 26 wt% CaCl 2 equiv) and highly oxidizing. Such fluids would have been particularly
favorable for uranium transport (Hedges et al., 1984) as uranyl-complexes in basinal brines
in the sandstone aquifer above the unconformity. Tectonic reactivation of the El Sherana-
Palette fault during deformation associated with the Nimbuwah event would have provided
structural conduits for hydrothermal basinal brines that descended downward into the
metamorphic basement rocks. Interaction between the oxidized U-bearing basinal brines
and the reducing carbonaceous shale of the Koolpin Formation would have led to U
reduction and precipitation. The occurrence of Au and PGE associated with quartz feldspar
porphyry at Coronation Hill may have resulted from acid neutralization and reduction
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