The Congararra 1 borehole was drilled approximately 70 km NNW of Bourke, NSW. The borehole was designed to test aeromagnetic anomalies in the basement rocks, test the electrical conductivity properties of cover and basement rocks to validate airborne electromagnetic (AEM) data, and to test pre-drilling geophysical cover thickness estimates.

The Euroli 1 borehole was drilled approximately 23 km SSW of Hungerford, Queensland (which is located on the New South Wales-Queensland border). The borehole was designed to test aeromagnetic anomalies in the basement rocks, test the electrical conductivity properties of cover and basement rocks to validate airborne electromagnetic (AEM) data, and to test pre-drilling geophysical cover thickness estimates. The Euroli 1 borehole was commenced as a vertical mud rotary borehole and was completed with a deviated diamond drilled tail using a wedge.

The Laurelvale 1 borehole was drilled approximately 78 km SSW of Wanaaring, New South Wales, adjacent to the through-road between Tongo and Tilpa. The borehole was designed to test the geology of indistinct, linear aeromagnetic anomalies in the basement rocks, test the electrical conductivity properties of cover and basement rocks to validate airborne electromagnetic (AEM) data, and to test pre-drilling geophysical cover thickness estimates.

<div>The study utilised Geoscience Australia’s vast data collection of mineral occurrences to identify the range of historical discoveries within the Officer-Musgrave, Darling-Curnamona - Delameian and Barkly - Isa - Georgetown Deep Dive areas. A literature review shed light on exploration discovery methods, commodity grades, exploration histories and deposit types. Many critical mineral occurrences were overlooked or ignored in the past, as the commodity discovered was not of interest or value at the time, or grades were regarded as sub-economic. However, with modern methods of mining, ore treatment techniques and increased demand, reassessment could now provide new opportunities.</div>

<div>Heavy minerals (HMs) are those with a specific gravity greater than 2.9 g/cc (e.g., anatase, zircon). They have been used successfully in mineral exploration programs outside Australia for decades [1 and refs therein]. Individual HMs and combinations, or co-occurrence, of HMs can be characteristic of lithology, degree of metamorphism, alteration, weathering or even mineralisation. These are termed indicator minerals, and have been used in exploration for gold, diamonds, mineral sands, nickel-copper, platinum group elements, volcanogenic massive sulfides, non-sulfide zinc, porphyry copper-molybdenum, uranium, tin-tungsten, and rare earth elements mineralization. Although there are proprietary HM sample assets held by industry in Australia, no extensive public-domain dataset of the natural distribution of HMs across the continent currently exists.</div><div> We describe a vision for a national-scale heavy mineral (HM) map generated through automated mineralogical identification and quantification of HMs contained in floodplain sediments from large catchments covering most of Australia [1]. These samples were collected as part of the National Geochemical Survey of Australia (NGSA; www.ga.gov.au/ngsa) and are archived in Geoscience Australia’s rock store. The composition of the sediments can be assumed to reflect the dominant rock and soil types within each catchment (and potentially those upstream), with the generally resistant HMs largely preserving the mineralogical fingerprint of their host protoliths through the weathering-transport-deposition cycle. </div><div> Underpinning this vision is a pilot project, focusing on a subset of NGSA to demonstrate the feasibility of the larger, national-scale project. Ten NGSA sediment samples were selected and both bulk and HM fractions were analysed for quantitative mineralogy using a Tescan® Integrated Mineral Analyzer (TIMA) at the John de Laeter Centre, Curtin University (Figure 1). Given the large and complex nature of the resultant HM dataset, we built a bespoke, cloud-based mineral network analysis (MNA) tool to visualise, explore and discover relationships between HMs, as well as between them and geological setting or mineral deposits. The pilot project affirmed our expectations that a rich and diverse mineralogical ecosystem will be revealed by expanding HM mapping to the continental scale. </div><div> A first partial data release in 2022 was the first milestone of the Heavy Mineral Map of Australia (HMMA) project. The area concerned is the Darling-Curnamona-Delamerian region of southeastern Australia, where the richly endowed Broken Hill mineral province lies. Here, we identified over 140 heavy minerals from 29 million individual mineral observations in 223 sediment samples. Using the MNA tool, one can quickly identify interesting base metal mineral associations and their spatial distributions (Figure 2).</div><div> We envisage that the Heavy Mineral Map of Australia and the MNA tool will contribute significantly to mineral prospectivity analysis and modelling in Australia, particularly for technology critical elements and their host minerals, which are central to the global economy transitioning to a more sustainable, decarbonised paradigm.</div><div><br></div>Figure 1. Distribution map of ten selected heavy minerals in the heavy mineral fractions of the ten NGSA pilot samples (pie charts), overlain on Australia’s geological regions (variable colors) [2]). Map projection: Albers equal area.</div><div><br></div><div>Figure 2. Graphical user interface for the Geoscience Australia MNA cloud-based visualization tool for the DCD project (https://geoscienceaustralia.shinyapps.io/HMMA-MNA/) showing the network for Zn minerals with the gahnite subnetwork highlighted (left) and the map of gahnite distribution (right).</div><div> <strong>References</strong></div><div>[1] Caritat et al., 2022, Minerals, 12(8), 961. https://doi.org/10.3390/min12080961 </div><div>[2] Blake &amp; Kilgour, 1998, Geosci Aust. https://pid.geoscience.gov.au/dataset/ga/32366 </div><div><br></div>This Abstract was submitted/presented to the 2022 Mineral Prospectivity and Exploration Targeting (MinProXT 2022) webinar, Freiburg, Germany, 01 - 03 November (www.minproxt.com)

The GSQ Cunnamulla 1 borehole was drilled approximately 110 km SE of Cunnamulla, Queensland. The borehole was designed to test aeromagnetic anomalies in the basement rocks, test the electrical conductivity properties of cover and basement rocks, and to test pre-drilling geophysical cover thickness estimates.

The Janina 1 borehole was drilled approximately 110 km W of Bourke, New South Wales. The borehole was designed to test aeromagnetic anomalies in the basement rocks and to test the electrical conductivity properties of cover and basement rocks to validate airborne electromagnetic (AEM) data.

The Milcarpa 1 borehole was drilled approximately 9 km SSE of Hungerford, Queensland, adjacent to the road between Hungerford and Wanaaring, NSW. The borehole was designed to test aeromagnetic anomalies in the basement rocks, test the electrical conductivity properties of cover and basement rocks to validate airborne electromagnetic (AEM) data, and to test pre-drilling geophysical cover thickness estimates.

The GSQ Eulo 4 borehole was drilled approximately 35.5 km SW of Eulo, Queensland. The borehole was designed to test aeromagnetic anomalies in the basement rocks, and to test the electrical conductivity properties of cover and basement rocks to validate airborne electromagnetic (AEM) data.

The Tongo 1 borehole was drilled approximately 83 km NE of White Cliffs, New South Wales. The borehole was designed to test aeromagnetic anomalies in the basement rocks and to test the electrical conductivity properties of cover and basement rocks to validate airborne electromagnetic (AEM) data.