North Australian Craton iron oxide-copper-gold (IOCG) mineral potential assessment: geospatial data

Brief description

Following the successful outcomes of the Tennant Creek-Mt Isa (TISA) mineral potential assessment (Murr et al., 2019; Skirrow et al., 2019), the methodology has been expanded to encompass the entire North Australian Craton (NAC). Like its predecessor, this assessment uses a knowledge-based, data-rich mineral systems approach to predict the potential for iron oxide-copper-gold (IOCG) mineralisation. With their high metal yield and large alteration footprint, IOCG mineral systems remain an attractive target in directing exploration efforts towards undercover regions. This mineral potential assessment uses a 2D GIS-based workflow to map four key mineral system components: (1) Sources of metals, fluids and ligands, (2) Energy to drive fluid flow, (3) Fluid flow pathways and architecture, and (4) Deposition mechanisms, such as redox or chemical gradients. For each of these key mineral system components, theoretical criteria representing important ore-forming processes were identified and translated into mappable proxies using a wide range of input datasets. Each of these criterion are weighted and combined using an established workflow to produce a models of IOCG potential. Metadata and selection rational are documented in the accompanying NAC IOCG Assessment Criteria Table. Two scenarios were modelled for this assessment. The first is a comprehensive assessment, targeting pre-Neoproterozoic mineral systems (>1500 Ma), using a combination of interpreted, geological and geophysical datasets. As geological interpretations are subjective to the geological knowledge of the interpreter, well-documented areas, such as shallow pre-Neoproterozoic basement, have a greater density of data. This increase in data density can create an inherent bias in the modelled result towards previously explored shallow terrains. The second assessment utilises only datasets which can be mapped consistently across the assessment area. As such, these are predominately based on geophysical data and are more consistent in assessing exposed and covered areas. However, far fewer criteria are included in this assessment, and observations are reflective of only the modern geological environment. Both assessments highlight existing mineral fields in WA, NT and QLD, and suggest that these regions extend under cover. Furthermore, regions not previously known for IOCG mineralisation display a high modelled potential, offering exploration prospects in previously unknown or discounted areas.

Lineage

Maintenance and Update Frequency: asNeeded

Statement: The data for this assessment have been sourced from geological, geophysical and geochemical datasets (see associated spreadsheet and references). The input datasets produced and used in this assessment were sourced from Geoscience Australia databases and are publicly available via the Geoscience Australia website and portal. Derivative products of the input datasets were developed for the assessment (e.g. buffered zones). Decisions concerning the development of these derivatives, such as the selection of buffer distances and assignment of cut-off values, were made subjectively based on the scientific judgement of the assessment team. Further information regarding the datasets used, data processing steps, criteria weightings and scientific rationale can be found in the accompanying data table. Scripts to automate GIS workflow (not available in this data package, to be released separately as a git) based off scripts by Coghlan (2015).

Notes

Purpose
This data release is intended to supply third parties to all the input and output data produced conjunction with the North Australian Craton IOCG mineral potential assessment. Sufficient documentation is provided so that third parties can re-create and modify the process to produce the same or similar results.