Round 15 GDC Program Irindina Undercover Aeromagnetic and Radiometric Survey Final Report

Abstract

In May 2022, IGO Limited (IGO) were successfully awarded co-funding in Round 15 of the Geophysics and Drilling Collaboration (GDC) Program administered by the Northern Territory Government. The co-funding was provided to complete an airborne magnetic and radiometric survey across five tenements in the eastern area of IGO's Irindina project in central Australia (EL 32778, EL 32780, ELA 32768, ELA 32769, ELA 32784). IGO consider the Irindina Province prospective for base metal discoveries, particularly magmatic nickel-copper-cobalt-platinum group element deposits. Historically this region has mainly been explored for volcanogenic massive sulfide and hydrothermal copper and uranium deposits. The tenements covered in the co-funded survey have not been systematically explored for magmatic sulfide mineralisation and remain largely untested, especially undercover. The objective of the airborne survey was to increase the resolution of magnetic and radiometric data for geology lying undercover in this part of the project area. The intrusions targeted generally have smaller geophysical footprints than can be delineated with the current regional 500m-spaced aeromagnetic surveys. The airborne magnetic-radiometric survey was completed totalling 12,416-line kilometres covering 1,114 km2 with a nominal terrain clearance of 30 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 the 27th of October 2022 and was completed on the 6th of November 2022. The higher resolution imagery generated has allowed more robust geological/structural interpretations. The increased aeromagnetic survey resolution has detected interpreted small mafic intrusions that may host magmatic sulfide deposits undercover. The new aeromagnetic results also help extrapolate recent revised stratigraphy for the province undercover where there were limited constraints. The radiometric data acquired allows IGO to interpret the regolith in more detail and assess which exploration methods are most amenable for follow-up work. Once land access is granted by the Central Land Council, all this new information will help IGO to precisely plan localised electromagnetic (EM) surveys and surface geochemistry sampling programs. These surveys will enable direct detection of base metal sulfides in mafic intrusions if they are present.