Proposed Title 1: - Queen's University

fracture systems created by brittle reactivation of the El Sherana-Palette fault at
temperatures near 250°C. Syn-ore mineral crystal chemistry suggests that uranyl-fluoridechloride
and -phosphate were dominant ore transporting complexes. Interaction of
oxidizing basinal brines with reducing Koolpin Formation sediments led to deposition of
the ore metals. Uranium deposits of the South Alligator Valley Mineral Field can therefore,
be classified as unconformity-related uranium mineralization associated with the El
Sherana successor basin. Post-ore alteration is dominated by secondary uraninite along late
fractures, kaolinite and hematite alteration, and chlorite and calcite veins, which formed at
temperatures near ca. 100°C. Post-ore alteration occurred during major tectonic events
based on U-Pb and Pb-Pb dating of uraninite and was coincident with fluid flow induced by
both near and far-field tectonic events that altered much of the primary uraninite into
secondary uranium minerals.
Our results show that the age of the uranium deposits are older than previously
proposed and are also older than the unconformity-related uranium mineralization in the
Kombolgie Basin. Unconformity-related uranium mineralization is associated with basinal
brines from the Paleoproterozoic successor basin, thereby enhancing the uranium
prospectivity of the area.
4.1. Introduction
The South Alligator Valley Mineral Field (SAVMF), Northern Territories, Australia,
lies within a north-west-trending zone of folded and faulted Paleoproterozoic
metasediments (Fig. 4.1) exposed within the South Alligator Valley in the Pine Creek
Orogen (Needham et al., 1980, 1987, 1988; Needham and Stuart-Smith, 1985, Valenta,
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