NTGS Record 2003-004 - REE mineralisation in the eastern Arunta

The following notes are derived from the abstract of Hussey KJ, 2003. Preliminary report on rare earth elements mineralisation in the eastern Arunta Region. Northern Territory Geological Survey, Record 2003-004. Contact the Information Centre (telephone +61 8 8999 6443 or email geoscience.info@nt.gov.au) for copies of this report, available free-of-charge.

The majority of the REE deposits in the Arunta Region appear to be small uneconomic prospects, but few have been fully evaluated. REE prospects have been identified on the basis of anomalous exploration rock chip REE geochemistry, or are previously identified locations where REE-bearing minerals are known to occur. Most prospects occur within the Irindina Province and adjacent areas in the southeastern part of the Arunta Region. These REE prospects appear to be related to a holistic model involving REE-enriched pegmatite or granite emplacement, with an associated hydrothermal REE-rich fluid-related event resulting in replacement or vein systems.

The timing of these REE deposits appears to be broadly associated with the Palaeozoic Alice Springs Orogeny. The Nolans Bore REE prospect is currently the largest known REE deposit in the Arunta Region with an estimated resource of about 3.8 Mt @ 4 wt% rare earth oxides within 60 m of the surface. Although it is spatially separated from REE deposits in the Irindina Province and the timing of mineralisation at Nolan Bore is unknown, broad geochemical similarities suggest that they could be related.

The potential for significant replacement or pegmatite-hosted REE deposits appears to be high, particularly in the southeastern Arunta Region where abundant REE-rich pegmatite swarms occur. Some prospects appear to have considerable REE potential (eg Holsteins) and there is potential for additional REE deposits in nearby areas. There is also some potential for REE mineralisation associated with additional unrecognised carbonatites and alkaline igneous complexes, and for supergene or lateritic enrichment deposits.