Exploring for the Future takes a deeper look at northern Australia

28 October 2021

A new electrical conductivity model released by Geoscience Australia’s Exploring for the Future program offers a deeper look at the geology in northern Australia with promising results.

Under the Australian Lithospheric Architecture Magnetotelluric Project (AusLAMP), a geophysical method called magnetotellurics (MT) is unlocking new information about the geology of Australia from tens to hundreds of kilometres beneath the Earth’s surface.

Chief of the Minerals, Energy and Groundwater Division at Geoscience Australia, Dr Andrew Heap, said that by measuring naturally occurring magnetic and electric fields, the technique offers a picture of the Earth’s crust and upper mantle - enabling a “bottom-up” approach for mapping areas across Australia with mineral potential.

“With this data, scientists can look beneath Australia’s cover like never before and visualise the Earth’s structure in areas that are currently poorly understood,” Dr Heap said.

“For example, this new model produced from the newly collected AusLAMP data covers more than one million square kilometres of northern Australia and reveals prominent electrical conductivity features that can be used to narrow the search for large mineral systems in this under-explored region.

“The model shows strong indications of iron oxide-copper-gold systems, orogenic gold systems and other copper/gold related mineralisation which will be of great interest to explorers.”

“Using the new model of northern Australia, we can see promising features, such as electrical conductors and resistors that extend deep below the Earth’s surface in the Northern Territory and Queensland.

Dr Heap said that major structures such as the Willowra Suture on the northern edge of the Aileron Province and the Kalkadoon-Leichardt Belt passing through Mount Isa have been imaged as never before through this model.

“Some of the trends we can see challenge our current understanding of the geological architecture of central Australia,” Dr Heap said.

“This highlights how crucial this information is for improving our understanding of the region’s resource potential.

”Importantly, for the first time the model shows conductors in the Tanami Province, an area known for its gold mines, and could be used to target exploration elsewhere in the region and in the Aileron Province.”

The new world-class MT dataset and model are designed to help industry and governments fill knowledge gaps around existing mineral and critical mineral deposits, and potentially unearth new ones.

Dr Heap said that similar models have revealed that large mineral deposits at Olympic Dam in South Australia and Ernest Henry in north-west Queensland are connected to electrical conductivity features in the deep Earth via narrow conductive pathways along which metals migrated to the surface to be concentrated in mineral deposits.

“These intriguing results provide a means for targeting future industry exploration activities in northern Australia.” Dr Heap said.

AusLAMP is a long-running collaborative, national survey, imaging the electrical structure of the Australian continental lithosphere in three dimensions (3D).

Geoscience Australia is collaborating with the state and Northern Territory geological surveys, AuScope and the University of Adelaide, the University of Western Australia and the University of Tasmania to collect long-period MT data at about 3,000 sites across Australia.

Conductors imaged by AusLAMP in the East Tennant region were a key consideration in focusing the recently successful stratigraphic drilling program in the area which demonstrated the presence of an iron oxide-copper-gold mineral system in this underexplored and buried exploration frontier.

In the past four years, 33 companies have now taken up tenements covering more than 165,000 square kilometres in the area between Tennant Creek and Mt Isa, in part due to similar AusLAMP models.

“In these challenging times, programs like Exploring for the Future continue to deliver the next round of investment and job creation,” Dr Heap said.

This uniquely positions Australia to meet the demands of a changing world, and supports our miners, explorers and farmers with the geoscience information they need to make informed decisions.”

Explore the AusLAMP model of northern Australia here: http://dx.doi.org/10.11636/Record.2021.021

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