GDC Collaborations Program Round 13 Final Report Western Willowra Gravity Ridge Airborne Magnetic and Radiometric Survey ELA 30116, ELA 30117, ELA 31857, ELA 31858, ELA 31859 and ELA 31860

Abstract

In July 2020, IGO Limited (IGO) were successfully awarded funding in Round 13 of the Geophysics and Drilling Collaboration (GDC) Program administered by the Northern Territory Geological Survey (NTGS). The funding was provided to complete an airborne magnetic and radiometric survey across six tenement applications in western areas of IGO's Raptor project. The objective of the airborne survey was to increase the resolution of magnetic and radiometric data over the Willowra Gravity Ridge in the northwestern Aileron Province. Historically this greenfields region has been mainly explored for orogenic gold mineralisation. Instead however, the gravity anomaly being surveyed is interpreted to represent Paleoproterozoic ultramafic and mafic intrusions with significant base metal potential. The tenements covering the Raptor Project have not previously been systematically explored for orthomagmatic sulfide mineralisation and remain largely untested. Historical drilling on current IGO tenements indicate the presence of nickel and copper mineralisation within targeted mafic intrusions confirming the prospectivity of local mafic bodies. This mineralisation was not previously followed-up by gold-focused explorers. Orthomagmatic nickel-copper mineralisation at Prospect D and volcanogenic copper-silver-zinc-lead mineralisation at the Home of Bullion deposit also occurs to the east of the Raptor Project. This indicates sulfide fertility in similar-aged Proterozoic mafic rocks regionally. Given these results, IGO considers the region highly prospective for base metal discoveries. Much of the geology in the proposed survey area is hidden under shallow cover. IGO are aiming to use the new airborne magnetic and radiometric data to confirm and understand local stratigraphy at depth and therefore increase geological knowledge of the area. The airborne magnetic-radiometric survey was completed totaling 26,484 line kilometres with a nominal terrain clearance of 50 m. The survey was flown at 100 metre spacing with 1000 metre tie lines improving the quality of existing government 500 metre spaced data. The survey commenced on 7th September 2020 and was completed on 4th November 2020. The greater granularity of imagery produced in the proposed survey now allows IGO to precisely plan more localised electromagnetic (EM) surveys and surface geochemistry sampling programs that will directly detect base metal sulfides in these mafic intrusions.