b'AEGC 2023Short abstractsCompositional geostatistics for modelling of coal seammineral co-occurrence relationships, which has application and associated ply properties. in exploration vectoring and targeting. The MNA tool can also be used to rapidly search the heavy mineral database to Kane Maxwell and Lauren Maxwell locate observations of potential economic significance. Stage 1 results revealed the co-occurrence of multiple Zn-minerals in Matrix Geoscience drainages surrounding the Broken Hill Pb-Zn deposit. These Zn-Compositional geostatistics are commonly employed forminerals (e.g., gahnite (Zn-spinel), ecandrewsite (Zn-ilmenite) spatial modelling of geochemistry when the geochemicaland zincostaurolite (Zn-aluminosilicate)) are interpreted to be analysis is a closed analysis (for example whole rockreflect high-grade metamorphism of base metal mineralisation. geochemistry which must sum to 100%). Likewise,Zn-mineral co-occurrences were also observed in locations not compositional geostatistics have previously been used toassociated with known mineralisation, and may represent new model coal quality properties derived from proximate andexploration opportunities.ultimate analysis, which are also considered closed analysis.Demonstrating the heavy mineral data from this stage 1 as The relationship between a coal seam and its plies can also bewell as stage 2 (new data covering parts of Queensland) using considered a special type of composition, whereby coal plythe MNA will be the focus of this presentation. Mineral assay properties must sum to equal that of the parent coal seam.data from all 1315 samples will be publicly released by the end Despite this, compositional geostatistics are rarely appliedof 2023.in stratigraphic modelling of coal plies and seams. Instead, rudimentary, or mathematically inconsistent approaches are applied to account for the compositional relationshipMineral exploration under cover and the value of between seams and plies. In this paper we use compositionalpetrophysicsa case study from east Albany-Fraser geostatistics to ensure that coal ply properties sum to thoseOrogen, Western Australia.of the parent coal seam and compare this method to existing methods which are commonly used in resource reports. ToKatherine McKenna 1 Thiago Oliveira1, Steve Rennick1 and compare methods, this paper uses proximate analysis dataClaire Mortimore2from a case study area in the Bowen basin, Queensland, Australia. Data is derived from over 200 borehole locations1 BHP from a coal seam with six coal plies. To evaluate the methods,2 Terra Resourcesaccuracy measures from leave one out cross validationGreenfield mineral exploration undercover presents a number are used. The results of the paper show compositionalof challenges. In the East Albany-Fraser Orogen, when faced geostatistics is mathematically consistent and is more accuratewith 300-700 m of cover and very little previous exploration, any at spatially modelling coal proximate analysis for the coalavailable data is valuable. Collection of petrophysical data is a seam and plies than exiting methods. cost-effective method to optimise the information in the available drilling with three main benefits: Firstly, an understanding of the Heavy mineral exploration on a continental scale: Thephysical properties of the cover sequence of the Eucla Basin and GA-Curtin Heavy Mineral Map of Australia project. the underlying basement will aid in the geophysical modelling and development of the basement mapping and mineral Brent McInnes1 Patrice de Caritat2, Alexander Walker1 andtargeting. Secondly, when the petrophysical data from a drill hole Evgeniy Bastrakov2 is effectively integrated with the mineralogy, geochemistry and observed lithology, a greater understanding of the geological 1 John de Laeter Centre, Curtin Universitycontrols of the petrophysical properties can be observed and 2 Geoscience Australiathe processes that are influencing them inferred. Finally, with Heavy mineral exploration techniques have been successfullycomprehensive integration of these datasets, we significantly used as exploration vectors to ore deposits around theincrease our confidence in the source, validity and interpretation world. However, heavy mineral exploration case studies andof the geophysical responses.pre-competitive datasets relevant to Australian conditionsA study was undertaken utilising Geological Survey of Western are relatively limited. The Heavy Mineral Map of AustraliaAustralia (GSWA) Exploration Incentive Scheme (EIS) open file (HMMA) project, part of Geoscience Australias Exploring fordrill hole data from East_Fraser Orogen. Peterophysical data the Future programme, is addressing this gap by determiningwere collected on the available core, which included magnetic the abundance and distribution of heavy minerals (specificsusceptibility, dry bulk density, apparent porosity, grain density, gravity 2.9 g/cm3) in 1315 floodplain sediment samples duringp-wave velocity, acoustic impedance galvanic resistivity, Geoscience Australias National Geochemical Survey of Australiachargeability and inducted conductivity. All drill holes reached (NGSA) project. Archived NGSA samples in floodplain landformsbasement, a few holes had cover that could be sampled, were sub-sampled and subjected to dense media separationall holes had different levels of geochemical assaying, and and automated SEM-EDS analysis. petrography was available for some of the holes.A stage 1 data package released in August 2022 containsThe results of the integration of the petrophysical data with mineralogical assay data for 223 samples from the Darling the mineralogy, geochemistry and observed lithology were CurnamonaDelamerian (DCD) region of south-easternmany. They included a strong correlation between the observed Australia. Stage 1 identified over 140 heavy minerals fromdensity in the core and lithological and mineralogical changes 29 million individual mineral observations. The number ofin the basement, a better understanding of the cover and the mineral observations generated during the project requiredsource and nature of its conductivity response, and a better development of a novel Mineral Network Analysis (MNA)understanding of the influence of metamorphism on the tool to allow end users to discover, visualise and interpretphysical properties of the rocks.119 PREVIEW FEBRUARY 2023'