Project activity National Geochemical Framework

A greater understanding of the surface of Australia

The surface of the Australian continent can provide valuable insights into the environmental, economic and agricultural landscape of the country, enabling informed decision-making for a range of industries. The National Geochemical Framework study primarily focuses on the rich archive of samples and data housed at Geoscience Australia. These samples are a precious resource.  In some cases they were collected prior to any development in an area, meaning they can provide baseline geochemical information about the area that would not be possible if the sample were collected today.  

What are we doing?  

Due to the diverse nature of the surface of Australia and the information that we can derive from it, the National Geochemical Framework study is split into the following activities: 

• Levelled Geochemical Baselines 
• Surface Mineralogy and Isotopic Signatures
  • Heavy Mineral Map of Australia
  • Strontium Isoscape of Australia 
• Geochemical Grids of Australia  

Each of these activities focuses on different ways of analysing and interpreting surface geochemical and mineralogical data. 

Levelled Geochemical Baselines 

The Levelled Geochemical Baselines activity builds on a pilot study that was undertaken in the North Australian Craton, which focussed on levelling the existing data. This levelling is designed to remove the variation in the data introduced by the analytical laboratory. This analytical variability would normally introduce slight differences between samples analysed at different times leading to inconsistent statistics and edge effects on maps. 

In this expanded project, archived samples from surveys spanning the last 50 years have been re-analysed using modern, higher-precision instruments and analysing a wider range of chemical elements, to bring the assay data for these samples up to modern standards. 

Following this re-analysis, the new data will be levelled with existing modern surficial geochemical surveys (National Geochemical Survey of Australia, Northern Australia Geochemical Survey, Southern Thomson Region Geochemical Survey).  

The combined datasets will be used to assist in refining geochemical grids of Australia, set environmental baselines and assist explorers to determine areas of interest.  

Objectives 

• Re-analyse samples from stream sediment surveys using modern analytical techniques. 
• Level the re-analysed data with existing modern surveys to produce a dataset that can be used seamlessly.  

Surface Mineralogy and Isotopic Signatures 

This activity will re-analyse archived samples to gain new insights into the distribution of heavy minerals and isotopes across Australia, as well as identifying new regions of interest. The work will contribute to mineral prospectivity assessments. 

Heavy Mineral Map of Australia 

Using samples from the continental-scale National Geochemical Survey of Australia (NGSA), new data on mineralogy have been collected to develop the Heavy Mineral Map of Australia. The Heavy Mineral Map of Australia is the world’s first publicly available, continental-scale, heavy mineral dataset and atlas.

Heavy minerals are used extensively around the world for mineral or energy exploration, including in the search for critical minerals. Through a collaboration with Curtin University, 1,315 archived samples from across Australia have been analysed for automated identification and quantification of heavy minerals. The analysis reveals information about the upland and shallowly covered bedrock, which is of particular importance in areas of cover, where traditional methods of exploration, such as geochemistry, can be ineffective.

The Heavy Mineral Map of Australia and accompanying cloud-based mineral network analysis (MNA) toolwill positively impact mineral exploration and prospectivity modelling around Australia, including for critical minerals, as well as have other applications in earth and environmental sciences.  

Objectives 

• Produce a map of the distribution of heavy minerals for NGSA sites. 
• Release the national scale heavy mineral dataset and accompanying Mineral Network Analysis tool to allow rapid and efficient analysis. 

Strontium Isoscape of Australia   

Through collaboration with the University of Wollongong, archived NGSA samples from large parts of eastern and northern Australia are being analysed for strontium isotopes. Isotopes are atoms of the same chemical element (in this case strontium) with different numbers of neutrons, giving the atom different mass and hence slightly different physical properties. Isotope ratios (proportions) can provide a ‘fingerprint’ of rock-types or geological processes. The strontium isotope system can shed light on the provenance of sediments, mixing with aeolian material, and potentially identify lithologies and mineral system components under shallow cover. A combination of total and partial digestion strontium analyses will provide essential data for constructing a map of strontium isotopes (an isoscape) that can assist in ecological and anthropological studies. 

Objective 

• Release data and maps of strontium isotopes in select areas. 

Geochemical Grids of Australia  

The Geochemical Grids of Australia activity is creating seamless, national-scale predictive surface geochemical maps of Australia. It applies machine learning algorithms in an automated workflow that relies on using a range of multi-disciplinary datasets (remote sensing, geophysics and geology), in combination with the wealth of curated rock and regolith geochemical data from Geoscience Australia and state/NT survey databases.  

These machine learning-derived maps will open new ways of viewing and interpreting geochemical data. By using national-scale covariates (input datasets) the resulting geochemical grids will be national-scale, despite the continent not having complete coverage of geochemical data. This will provide valuable predictions into areas of the country that lack data, e.g. because they are remote or otherwise difficult to access. 

Objectives 

• Produce predictive maps for the major geochemical oxides 
• Produce model uncertainties for each of the predictive major oxide maps 
• Generate selected ternary oxide maps showing the relationships between different oxides 
• Produce a simplified classification of major oxide groups 
• Produce a report describing the distribution of major oxides over the Australia continent 
• Release the key covariates (input datasets) used for machine learning 
• Differentiate the geochemistry of soil/regolith from bedrock materials 
• Release of codes and workflows for predictive mapping via gitHub.