Widening the search space

20 May 2019 5 min read

Despite iron ore being the top mineral resource export in recent times in Australia, the prospect of discovering gold in Western Australia's (WA) outback continues to attract mining companies and investors with the promise of making their fortune.

It is a well-known and established mineral jurisdiction, and although techniques and technologies have inevitably changed since the first gold discoveries in the 19th century, a new and modern approach to gold exploration could further raise WA’s and – by extension Australia's – profile as a global producer and unify the way in which gold miners search for gold.

Mapping the eastern goldfields of Western Australia

A 10-year research and development effort led by the Minerals Research Institute of Western Australia (MRIWA) along with CSIRO and the exploration industry, has mapped key areas of the eastern goldfields in WA to better understand the larger mineral systems in which gold deposits could be found in.

The collaboration's industry sponsors include gold producers Northern Star Resources, Gold Road Resources, Ramelius Resources, Evolution Mining, Blackham Resources, Saracen Mining and Echo Resources.

Traditional gold exploration has tended to focus on the individual deposits, however MRIWA research portfolio manager, Anil Subramanya, says a deeper insight into mineral systems can help gold miners better plan and execute their exploration campaigns and assist in determining the proven resources of their tenement.

"CSIRO found that certain indicator minerals give you an idea of the conditions in which the deposits were formed. This helps exploration companies find gold deposits, determine how big they are and see what else might be found in the ground that they hold," Dr Subramanya says.

"When you study a deposit, the data obviously tells you about the deposit. But the deposit is part of a larger geological phenomena at the camp or regional scale.

Understanding large-scale geological phenomena

"This research takes a "big picture" approach to essentially expand the exploration scale from that of the immediate deposit for particular mining companies, to a larger camp scale.

"By supporting a long-term collaboration, we have helped the development of new exploration research data and a data analysis method for gold mineral systems that, in the short term, may lead to additional gold and precious metal discoveries in the target region.

The research data is being used by the industry sponsors and will eventually be made publically available through open access platforms. In addition to this, MRIWA and CSIRO are looking to turn the method for interpreting the data into a commercial product.

New exploration methodology

"We are supporting CSIRO’s development of an exploration methodology that leads to a better understanding of why and where the deposits are located, and also the extent of those deposits," Dr Subramanya says.

"There is potential for this to be a commercial product and I think the exploration companies involved in the project have already been successful in using the tool to design and manage their exploration programs.

"It's an ongoing positive result for companies when they sponsor these types of projects because they are getting feedback from the researchers about their findings, and that’s being continuously put back into their business loop in terms of how you design exploration programs.

"Continuity of funding over multiple projects can result in fundamental research transitioning into application."

Archean gold systems

Although Archean gold systems have been studied for many years, CSIRO research scientist, Adam Bath, says there is still plenty more to learn about them.

"We don't understand a great deal about the types of hydrothermal fluids that helped to create some of the most well endowed gold terranes on the planet," Dr Bath says.

"And WA is host to some of the richest gold provinces in the world.

"So we are trying to map them and understand the fluids through the minerals that are in there."

Finding gold deep under cover

As well as this scientific challenge, there is also the exploration challenge: how do you find gold systems under cover? A lot of these systems are buried under 50 or 100 meters of cover, or sometimes greater.

"Our research team is looking at how to use the minerals to identify how close or far we are from a system," Dr Bath says.

The data gathered from mapping and analysing the WA mineral systems are already helping the gold miners involved to create more targeted and comprehensive exploration campaigns.

According to Dr Bath, their analysis method could be used by commercial laboratories to gather and interpret data on mineral systems for gold miners.

"We are at the critical point in demonstrating that this proof-in-concept is something that you can apply and the hope is that companies will want to do this routinely," Dr Bath says.

"We've had industry sponsors for the past eight to nine years, who have increased their investment in the mineral systems research over time.

"So there's a general appetite to get in and map these systems, and now we have got commercial laboratories interested in partnering with CSIRO to offer that.

"And that’s what I see as our interest in this. It's understanding the science, creating a commercial application to it and then partnering with private enterprises to take that knowledge and apply it."

Mineral systems approach to discover copper, nickel and other commodities

Both Dr Bath and Dr Subramanya agree that the mineral systems science approach can be applied to finding other commodities like copper and nickel. This could, in turn, provide more exploration avenues for mining companies to pursue.

By allowing researchers to conceptualise mineral systems more broadly, they can look for commonalities and compare the data to similar formations.

"The next iteration of this project could be to expand the envelope to other commodities and regions," Dr Subramanya says.

"Different hydrothermal fluids form base metal deposits, and so the chemical signatures are created by different minerals to gold."

And because different minerals are formed during different temperature conditions these minerals must correlate to certain physical and chemical conditions.

"The research is being carried out at CSIRO, including the analytical work, and could potentially enable large commercial laboratories to use the methodology to widen the range of analyses on offer," Dr Subramanya says.

"It could be applied to Australia and overseas in similar geological environments, so there is no reason for it to be confined to WA.