A Mineralisation Age for the Sediment-Hosted Blackbush Uranium Prospect, North-Eastern Eyre Peninsula, South Australia

摘要: The Blackbush uranium prospect (~12,580 tonnes U at 85 ppm cut-off) is located on the Eyre Peninsula of South Australia. was discovered in 2007 and currently single example sediment-hosted mineralisation investigated any detail Gawler Craton. Uranium hosted within Eocene sandstones Kanaka Beds and, subordinately, a massive saprolite derived from subjacent Hiltaba-aged (~1585 Ma) granites, affiliated with Samphire Pluton. mainly present as coffinite different lithologies, styles mineral associations. In sandstone saprolite, occurs intergrown framboidal Fe-sulphides lignite, well coatings around, filling fractures within, grains quartz. Microprobe U–Pb dating sedimentary units yielded narrow age range, weighted average 16.98 ± 0.16 Ma (343 individual analyses), strongly indicating coffinite-forming event that time. Coffinite generated broader range 28 to 20 Ma. Vein-hosted similar ages (from 12 25 Ma), albeit greater range. Uraninite vein distinctly older (42 38 Ma). 17 for sandstone-hosted roughly coincides tectonic movement indicated by presence horst graben structures rocks hosting but not stratigraphically younger rocks. new hydrothermal minerals support conceptual genetic model which initially sourced granite bedrock, then pre-concentrated into veins granite, subsequently dissolved reprecipitated sediments result low-temperature activity associated events during Tertiary. obtained here lithologies along reactivated Roopena Fault, triggered flow U-rich fluids cover sequence. timing provides information can help optimise exploration programs analogous resources shallow buried across region. presented be predicted apply U-mineralisation cratons elsewhere.