Heavy minerals (HMs) (i.e. minerals with a density greater than ~2.9 g/cm3) are widely used by mineral explorers and researchers in upstream exploration and geological provenance studies (e.g. Averill 2001; McClenaghan et al. 2016; Salama et al. 2016). Some HMs, referred to as ‘indicator’ minerals, can be indicative of specific environments of formation or processes such as hydrothermal alteration and mineralisation (e.g. Nowicki et al. 2007; McClenaghan et al. 2014; Mao et al. 2017). The use of HMs in mineral exploration typically involves the systematic sampling and analysis (geochemical and mineralogical) of drainage sediments, however the applicability of these methods in Australia is poorly understood due to the variable and, in places, protracted history of physical and chemical weathering across the continent, as well as the possibility that geomorphic drainage patterns and erosion cycles have evolved significantly over geological time (Pillans 2007; Pain et al. 2012).
The Heavy Mineral Map of Australia (HMMA) project is a joint Geoscience Australia-Curtin University initiative designed to define a heavy mineral baseline for the Australian continent. The starting materials utilized were 1315 floodplain sediment samples collected from drainage catchments covering ~81% of the Australian continent (Caritat 2022). A pilot study (Caritat et al. 2022) carried out on a subset of National Geochemical Survey of Australia (NGSA) samples determined that the largest volumetric component of the sediments was quartz and feldspar group minerals, which are of minimal diagnostic value in mineral exploration or determining basement geology. The heavy mineral fraction, separated from the bulk sediments using gravity separation techniques, was found to contain mineral assemblages of potential utility in defining protolith sources and geological processes related to magmatism, metamorphism, metasomatism/alteration, and mineralization. The Caritat et al. (2022) study determined that it was feasible to generate heavy mineral maps of Australia (HMMA) as a new pre-competitive asset of potential interest to industry, government, and academic researchers. The derived mineralogy from the HMMA project will provide explorers with a better understanding of background mineral abundances and geoscientists with new insights into the composition and evolution of the Australian crust.
