Proposed Title 1: - Queen's University

stable isotope geochemistry, U-Pb geochronology of paragenetically well-characterized U-
rich minerals, and chlorite and uraninite crystal chemistry. These results are used to identify
key processes controlling U mineralization in the SAVMF, present a genetic model for U
mineralization, and compare the South Alligator Valley U deposits to those in the younger
and U-rich Kombolgie Basin.
4.2. Geologic Setting
4.2.1. General geology
The South Alligator Valley area, Northern Territories, Australia (Fig. 4.1) comprises
rocks dated from Neoarchean to Paleoproterozoic, which are divided into four main
sequences. 1) Neoarchean basement granitic units (ca. 2.5 Ga; Needham and Stuart-Smith,
1985; Needham et al., 1988); 2) Paleoproterozoic sedimentary rocks of the Pine Creek
Orogen (2200 Ma to 1870 Ma) uncomformably overlying Neoarchean basement rocks
(Needham et al., 1987); 3) Paleoproterozoic silisiclastic red beds and associated volcanic
rocks of the El Sherana-Edith River Group (1829 Ma to 1822 Ma), which uncomformably
overlie Pine Creek Orogen sediments (Jagodzinski, 1992); and 4) late Paleoproterozoic
sedimentary rocks of the Kombolgie Basin (1822 Ma to 1720 Ma; Sweet et al., 1999)
uncomformably overlying older rocks and intruded by the 1723±6 Ma Oenpelli dolerite
(e.g. Kyser et al., 2000).
In the SAVMF, the oldest exposed unit of the Pine Creek Orogen sequence is the
Mundogie sandstone of the Mount Partridge Group (2025 Ma, Worden et al., 2004),
followed by the Koolpin Formation, the basal unit of the South Alligator Group (Needham,
1987). Sedimentation of the Koolpin Formation was accompanied by felsic volcanism,
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