Potential for magmatic uranium systems in Australia Map 1: Intrusive-related

Intrusive-related U mineralisation constitutes only a small proportion of Australia's known U resources despite the widespread occurrence of U-rich intrusive igneous rocks across both time and space. Due to this apparent discrepancy, the potential for intrusive-related U systems has been assessed on a continental scale using a GIS-based approach. This approach focuses on identifying those units or magmatic events which are the most favourable for the presence of magmatic-related U systems. Thus, the results do not necessarily identify likely locations of mineralisation, but rather are intended to form the basis for area selection and detailed follow-up work. This map uses surface geology, and therefore no information is given of the potential for these systems undercover. This map applies a mineral systems approach to assessing the potential for intrusive-related U systems, which is translated into mappable geoscientific criteria. The mineral systems model has three components: (1) melt generation; (2) U concentration; and (3) U deposition. Prospectivity criteria for melt generation (1) are the distribution of peralkaline or high temperature, high halogen I- or A-type melts, and the distribution of felsic igneous rocks. U concentration (2) is facilitated by fractional crystallisation, which is quantified using Rb/Sr, and exhibits itself in elevated U or high field strength element contents. U deposition (3) is mapped using U2/Th radiometric anomalies. The 'fuzzy logic' method is used to combine the disparate prospectivity criteria developed. The result gives an indication of the potential prospectivity on a scale of 0 to 1. The study has confirmed the favourability of already known U provinces, such as the Curnamona Province of South Australia and the Pine Creek region of the Northern Territory. However, new potential has been highlighted in regions not currently well-known for intrusive-related U mineralisation, such as the Arunta, Halls Creek and northern Musgrave regions. Note that the potential indicated here does not include other 'hybrid-style' systems, which may also have a genetic association with igneous rocks, such as the Olympic Dam IOCG-U deposit.