The East Tennant region (East Tennant) of the Northern Territory (NT) has been of heightened interest to mineral explorers over the past few years as an emerging copper–gold exploration frontier. This is largely due to collaborative pre-competitive geoscience work programs conducted by Geoscience Australia (GA) and the NT Geological Survey (NTGS), which highlighted that Proterozoic basement underlying the Cambrian cover of the Georgina Basin was prospective for iron oxide–copper–gold (IOCG) mineral systems (Schofield et al 2020). Results from the Mineral Exploration Collaboration Research Centre (MinEx CRC) National Drilling Initiative (NDI) East Tennant drillhole samples yielded further geochronological evidence to support the prospective nature of East Tennant for IOCG deposits (Kositcin et al 2022).
The deposits of the Tennant Creek district occur as polymetallic (gold–copper–bismuth, referred to as Au– Cu– Bi), selective partial replacements of small metasomatic ironstones (magnetite–hematite) that form within the clastic metasedimentary rocks of the Warramunga Formation (Partington and Williams 1999). Ironstones typically occur as flattened elongate bodies that range in size from a few tonnes to over 15 Mt, all of which are thought to be hosted by the Warramunga Formation (Donnellan 2013).
The Tennant Creek Au–Cu–Bi deposits have been classified as IOCG-style deposits (Skirrow 2019). There are several key geological commonalities within the deposits of Tennant Creek, most notably the generally close association with the ironstones within the region, although, significantly, not all ironstones are mineralised. Alteration patterns are typically similar across the deposits and form as pipe-like chlorite-rich alteration zones above and below the deposits, commonly accompanied by carbonate, talc with local muscovite, and variable quartz (Huston et al 2020). Recent studies indicate that felsic volcanics of the Ooradidgee Group, which unconformably overlies the Warramunga Formation, may act as a relatively impermeable ‘cap’ to mineralising fluids in Warramunga-hosted Tennant Creek-style IOCG deposits (Austin et al 2024).
Knox Resources Pty Ltd (Knox) was an early entrant to exploring within the East Tennant province with its exploration focused on the IOCG deposit family, and in particular, Tennant Creek-style ironstone associated Au– Cu–Bi mineralisation.
Knox, an 80%-owned subsidiary of Astute Metals NL, holds ten granted Exploration Licences (ELs) and three EL applications over four distinct locations, covering over 4500 km2 between the IOCG provinces of Tennant Creek and Mount Isa (Figure 1). Most of Knox’s tenements are located in the East Tennant region near the Barkly Roadhouse within the Warramunga Province (EL32281–82, EL32296, EL33375-76). EL32285 and EL32286 are located east of this area, in the Ranken project in South Nicholson Basin (Figure 1).
Located centrally within the Knox tenement holding, EL33375 has a cluster of prospect areas with IOCG deposit characteristics, including spatially associated magnetic and gravity high anomalies, presence of interpreted Warramunga Formation equivalents, and proximity to regional-scale faults and granitic intrusive rocks. Exploration work conducted by Knox to date on this tenement has been actively supported by the NTGS and the NT Government Resourcing the Territory initiative, with successful co-funding applications as part of the Round 15 and Round 16 Geophysics and Drilling Collaborations programs (Table 1). Work completed includes 100 m line-spaced airborne magnetic surveying, prospect-scale (200 m x 200 m station spacing) gravity surveying and the drilling of three exploration diamond holes at the Banks, Leichhardt West and Leichhardt East prospects.
The most recent work program comprised an Ambient Noise Tomography (ANT) geophysical survey, with a primary objective to delineate the Georgina Basin cover sequence contacts, as well as faults, other structural features and, potentially, zones of IOCG alteration. It was further proposed, as part of a successful Round 16 co-funding application, that results of the survey might assist with constraining future geophysical inversions.
