Proposed Title 1: - Queen's University

160 o C at Coronation Hill. The temperature of ca. 300 o C at the El Sherana deposit is
consistent with fluids derived from low grade greenschist metamorphic processes (Wyborn
et al., 1991). Extensive hematite inclusions in pre-ore Qtz 2 quartz veins (Fig. 4.5D) at the
Coronation Hill deposit suggest that pre-ore metamorphic fluids were highly oxidized (e.g.
Mernagh et al., 1994).
A Sensitive High Resolution Ion Microprobe (SHRIMP) U-Pb age of 1827±3 Ma for
the Pul Pul Rhyolite (Jagodzinski, 1998) near the top of the El Sherana Group indicates that
sediments of the El Sherana Basin could have begun to accumulate well before ca. 1830
Ma during deformation associated with the Nimbuwah event (Fig. 4.15B). Ahmad et al.
(2006) suggested that the initial deposition of El Sherana Group sediments occurred at
around ca. 1865 Ma associated with graben formation centred on the South Alligator River
valley. Therefore deposition of the El Sherana Basin sediments took place rapidly in a
tectonically active environment associated with the Nimbuwah Orogen (Friedmann and
Grotzinger, 1994). The prevailing geothermal gradient must have been higher compared to
the younger and larger Kombolgie Basin.
Petrographic analysis of the Coronation sandstone at the El Sherana deposit indicate
features typical for diagenetic alteration processes (Fig. 4.10), including well developed
Qtz 2 quartz overgrowths outlining detrital Qtz 0 quartz grains accompanied by partial to
complete resorption and pressure solution features that occurred during compaction at deep
burial levels. Extensive Kln 1 kaolinite alteration that is associated with development of
secondary porosity indicates that there were diagenetic aquifers in the El Sherana Basin
sandstone, which could have conducted U-bearing basinal brines (Fig. 4.15B). This
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