Airborne electromagnetic data is revolutionising Western Australian mining 

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estern Australia has completed the largest-ever airborne electromagnetic (AEM) survey of the region. The deliverables contained in the various data release packages include: the survey logistics and processing report; line data; processed electromagnetic, magnetic and elevation grids and conductivity estimates. 

The mapping was conducted under the aegis of the $225m Exploring for the Future project and funded through Western Australia’s Exploration Incentive Scheme. It was carried out and completed last year by Geoscience Australia in collaboration with the Geological Survey of Western Australia, and these collaborations could prove to set a new precedent for Australian mining.

The data covers the entirety of Western Australia and is expected to provide miners with a massive improvement in their understanding of the state’s geology. Although 100% of Western Australia has now been mapped, using AEM data, similar coverage of Australia’s total land area remains at just over 60%. 

The AEM technique enables mapping of the subsurface electrical conductivity of rocks, sediments and waters. It is a non-invasive testing technique that can detect variations in the conductivity of the ground to a depth of several hundred metres.  

“Previous surveys by Geoscience Australia using wide line spacing have shown the utility of the method in mapping cover thickness and its character,” explains the Geoscience Australia website, pointing to examples of how the data can be used on a local level. “The survey results are also used by the groundwater community to assess the potential for groundwater resources in Australia's arid zones to support remote communities in the survey areas.”

Companies already making use of the survey’s early-release AEM data include: Buxton Resources, Mamba Exploration and Torque Metals, as industry leaders look to take advantage of any innovations in data collection. 

Buxton Resources has located an unidentified bedrock conductor at its Narryer nickel-copper-platinum group elements (PGE) project in the West Kimberley. The Narryer Terrane forms part of the Western Yilgarn Craton margin which hosts the recently discovered Julimar nickel-copper-PGE project. Mamba Exploration has located targets at its Copper Flats project in the East Kimberley using AEM.  

Torque Metals, meanwhile, has found anomalies that may indicate nickel mineralisation at its Paris Copper-Gold project, the company’s cornerstone project, in the Eastern Goldfields. At the end of last year the company announced that it had restarted drilling at its 100%-owned flagship project in Western Australia based on the anomalies, and these examples point to a range of uses for the process that remains at its early stage. 

Describing the process, and whether it could set a precedent for other data collection in the state in the future, Mike Barlow, Geoscience Australia’s director of geophysics acquisition and processing says that: “This survey gives unprecedented insight into the top 300 metres of terrain across Western Australia, with 100% of the state now mapped using airborne electromagnetic technology. 

“With this information we can deepen our understanding of basin structure, faulting, clays, salinity and even direct detection of minerals,” Barlow continues. “We believe these results will invariably spark interest and set a precedent for additional datasets to be acquired by both industry and government who will use this data as a starting point to look more closely at areas of interest.” 

Barlow was also eager to point out that some data is yet to be released, and that this process of improving access to data remains an ongoing process. 

Geoscience Australia will continue to provide precompetitive data and information to inform decision-making by government, communities and industry on the sustainable development of Australia's mineral, energy and groundwater resources. 

The response from industry has so far been extremely positive, according to Barlow. “The data offers insights that will enable discoveries of key mineral systems across the region,” he continues.  “We have already seen examples of our data uncovering the potential for large-scale, underground storage of hydrogen in salt caverns in the Canning Basin, in northern Western Australia. 

“Additionally, several companies have identified bedrock anomalies relating to nickel-copper-platinum group element mineralization which may be similar to those at Julimar, the discovery of which was underpinned by Geoscience Australia’s precompetitive research, and was the biggest discovery of its kind in more than 20 years.” 

This positive response from the industry extends to a number of other projects and companies, where actors are looking to use the process to collect data in new ways.  NickelSearch, for instance, which is focused on advancing its flagship Carlingup Nickel Project near Ravensthorpe, has started drill testing targets that have been identified by moving-loop and airborne AEM surveys. 

NickelSearch’s managing director Nicole Duncan commented on the company’s website: “We are excited to start drilling to test the strong indicators of mineralisation at Javelin. The modelled down-hole EM plates and anomalous mineralisation seen in assays suggest we are close to a mineralised area. 

“In addition to Javelin, we are thrilled to be able to test new prospects at Sexton and RAV8 South,” continued Duncan. “We have been eager to drill at Sexton since first defining it as a high-priority target, so it’s great to be on the cusp of doing just that. At RAV8 South, it is logical to be exploring in proximity to the former RAV8 mine. It produced 16,100 tonnes of nickel at 3.45% nickel, including 9,600 tonnes of nickel at 5.83%, so we know the geology can hold exceptional high-grade nickel massive sulphides.” 

All in all, the data from the AEM survey should prove to be a game changer for the Western Australian mining industry. 

“The data has been met with a lot of excitement from industry and we know from other data releases that we are likely to see new tenement uptake across the region,” adds Barlow. “The data offers insights that will enable discoveries of key mineral systems across the region and encourage exploration of critical minerals that are fundamental in our transition to net-zero emissions by 2050.”