Published March 15, 2023 | Version v1
Conference paper Open

Heavy mineral exploration on a continental scale: The Geoscience Australia - Curtin University Heavy Mineral Map of Australia project

  • 1. John de Laeter Centre, Curtin University, Perth, Australia, b.mcinnes@curtin.edu.au
  • 2. Geoscience Australia, GPO 378, Canberra, Australia, patrice.decaritat@ga.gov.au
  • 3. John de Laeter Centre, Curtin University, Perth, Australia, a.walker@curtin.edu.au
  • 4. Geoscience Australia, GPO 378, Canberra, Australia, evgeniy.bastrakov@ga.gov.au

Description

Heavy mineral techniques have been successfully used as exploration vectors to ore deposits around the world. However, heavy mineral exploration case studies and pre-competitive datasets relevant to Australian conditions are relatively limited. The Heavy Mineral Map of Australia (HMMA) project, part of Geoscience Australia's Exploring for the Future program, is addressing this gap by determining the abundance and distribution of heavy minerals (specific gravity >2.9 g/cm3) in 1,315 floodplain sediment samples obtained from Geoscience Australia's National Geochemical Survey of Australia (NGSA) project. Archived NGSA samples from floodplain landforms were sub-sampled and subjected to dense media separation and automated mineralogy assay using SEM-EDS analysis. A stage 1 data package released in July 2022 contained mineralogical assay data for 234 samples from the Darling- Curnamona-Delamerian (DCD) region of south-eastern Australia. A stage 2 data package for 188 samples within the Barkly-Isa-Georgetown (BIG) region of north-eastern Australia was released in December 2022. The massive number of mineral observations generated during the project (150 million mineral observations anticipated; 166 unique mineral species identified to date) required development of a novel Mineral Network Analysis (MNA) tool to allow end users to discover, visualise and interpret mineral co-occurrence relationships. The mapping function of the MNA tool can also be used to rapidly search the heavy mineral database for the purpose of exploration targeting. Stage 1 results revealed the co-occurrence of multiple Zn-minerals in drainages surrounding the Broken Hill Pb-Zn deposit. These Zn-minerals (e.g., gahnite (Zn-spinel) and ecandrewsite (Zn-ilmenite)) are interpreted to reflect high-grade metamorphism of base metal mineralisation. Zn-mineral co-occurrences were also observed in locations not associated with known mineralisation, and may represent new exploration opportunities. Demonstrating the heavy mineral data from both stage 1 and 2 releases using MNA will be the focus of this presentation. Mineral assay data from all 1,315 samples will be publicly released by the end of 2023.

Notes

Open-Access Online Publication: May 29, 2023

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