Producing Magnetite and Hematite Alteration Proxies using 3D Gravity and Magnetic Inversion: Method and results for the Tennant Creek—Mount Isa Project, northern Australia

<p>The Exploring for the Future (EFTF) initiative aims to reduce the technical risk of mineral exploration by providing pre-competitive data and information to support investment and mineral exploration in northern Australia – a key part of ensuring Australia's future economic prosperity. <p>To support the EFTF initiative, the presence of hydrothermal alteration systems associated with iron oxide copper-gold (IOCG) deposits were estimated throughout the Tennant Creek -– Mt Isa Project area of northern Australia. These zones are of economic interest due to their potential to host copper, gold, uranium and rare earth element mineralisation. <p>To predict the presence of IOCG-related alteration, gravity and magnetic intensity data were used to produce 3D models of density and magnetic susceptibility, respectively. The inversion models provide an indication of the volume and distribution of these physical properties within the subsurface and were used to define volumes with relatively high densities and high magnetic susceptibilities as proxies for magnetite-rich alteration and volumes with high density, but low magnetic susceptibility, as proxies for hematite-rich alteration. <p>Contact zones between these two sets of volumes are considered to be the most favourable areas for potential IOCG mineralisation. However, the inversion modelling inevitably will have mapped a number of ‘false positives’, which will require more detailed inversion modelling and/or other data sets to discriminate these from true IOCG-related alteration.