An open-access, central repository for the nation’s groundwater data, is fast becoming a valuable tool for minerals exploration, covering 900,000 bore locations and logs, as well as interactive 3D hydrogeology models. JANE NICHOLLS reports
Open access groundwater data
Offering a central repository for the nation’s groundwater data, the Australian Bureau of Meteorology’s (BoM) Australian Groundwater Explorer has quickly become a powerful tool for everyone from policymakers to pastoralists.
Its features include open access information on more than 900,000 bore locations and logs, as well as interactive 3D hydrogeology models.
Now the latest data upgrade to the Explorer, which adds CSIRO and Geoscience Australia hydrogeochemistry data, is turning this resource into a powerful tool for minerals exploration.
The tool’s hydrogeochemistry datasets cover almost all of Australia, with Tasmanian data to be added soon. Most of these samples were originally collected and analysed by the water departments of the states and territories, with CSIRO undertaking the mammoth task of collating, standardising and running quality assurance and control checks on the data. The data reveals hydrogeochemical signatures of groundwater.
Mineral signatures in groundwater
"We're primarily trying to find what the signature of a mineral deposit looks like in groundwater," CSIRO team leader, Nathan Reid, says.
"We then see if we can find similar signatures in other areas that are not near known mines. There's a lot of exploration now going on with companies looking at the data and trying to find new deposits based on it."
Australian Groundwater Explorer
The Australian Groundwater Explorer was born in 2014 thanks to a government imperative to centralise precious water data.
"Groundwater data is collected and managed by each state and territory, and each one has their own database, their own formats and terminology," BoM senior hydrogeologist, Eloise Nation, says.
"To collate data in the past, you had to go to each of these agencies separately to collect it, standardise it and stitch it together.
"It was a lot of work and it was difficult to get a picture at the national scale of what Australian groundwater was doing."
The Australian Groundwater Explorer forms a key part of the BoM's suite of groundwater information products and brings together data on bore locations and logs, groundwater levels, and salinity measurements.
CSIRO and Geoscience Australia had long been collecting groundwater samples and doing deep analysis on its hydrogeochemistry, but this detailed data was available either internally on hard drives or at best via non user friendly portals.
Boosting the dataset through collaboration
BoM collaborated with CSIRO and Geoscience Australia to add this data to their Explorer to boost the resource and make this data openly accessible.
"The majority of groundwater originates as rainfall – it hits the ground, goes through soil, rocks, the aquifer, and at some point in its journey, we sample it from a bore," Geoscience Australia's, Luke Wallace, says.
"That water is trying to tell us the story of where it came from. It has a chemical signature from every rock it’s passed through, and we use chemical fingerprinting to unravel the detective story and join the dots."
These chemical signatures help to piece together a picture of the systems lying beneath.
"It gives us the potential to 'see' through 30 metres and even beyond 100 metres of cover," Dr Reid says.
"Some other exploration techniques are hampered if the bedrock is covered by sediments and sands. But as water moves through rock, a little bit dissolves here and there, and that signature is preserved to give us an idea of what the underlying geology is like."
Water holds the clues for multiple mineral targets
Water is the quiet collector of these precious clues.
"It's a passive sampling technique – we listen to the data and work out the story," Dr Wallace says.
Groundwater hydrogeochemistry data is another technique in the exploration tool kit to help understand the underlying geology beneath the sands and sediments masking it.
"We analyse groundwater samples for 60 odd elements and a few other parameters, isotopes and sometimes age dating," Dr Reid says.
"We're basically looking for everything: gold, nickel-copper, uranium, platinum and palladium systems."
"We throw the book at the water and see what it tells us, rather than trying to find a specific target. That's been one of the failings of how companies have approached sampling in the past. If they're looking for gold, they might only analyse for gold and a couple of other pathfinders, which means they might miss a nickel or copper deposit.
"Our aim is to find out about the geology, which can help target areas of interest based on whether you’re in a prospective rock type."
Comprehensive multiple parameter analyses
Geoscience Australia analyses for some 120 different compounds and other parameters.
For the past three years they have been doing comprehensive suites of analysis to assemble data to help the scientists of tomorrow.
"We realise we may not come back to this bore in the future, and that we’re likely to have more questions than we have right now. So we’re thinking about the future and analysing for everything."
"We look at field parameters, major and minor elements, traces, precious metals, a whole suite of isotopes, noble gases and organic gases," Dr Wallace says.
"We're looking from a minerals, groundwater systems and energy perspective, and we can provide environmental baselines, as well as exploration tools."
Sampling apps create a digital field notebook
CSIRO has adapted a sampling application (FAIMS Android app), which was developed by Macquarie University. This open-source field app helps to standardise the hydrogeochemistry data from all sampling.
"It's basically a digital field notebook and we encourage everybody collecting groundwater to use that and then all the data comes in the same format," Dr Reid says.
Adding value to the Explorer database, CSIRO has released the Hydrogeochemical Mapping of the Australian Continent report, along with state by state hydrogeochemistry atlases that provide interpretation and an in depth look at the data.
"The atlases look at all the hydrogeochemical data from each state and make interpretations based on the statewide geology," Dr Reid says.
"The atlas includes interpretations on major aquifer systems, how they were behaving, whether we could see known deposit styles in the state data and then if there were any areas of interest in the data that were not near known deposits and might be worth exploration follow up."
Hydrogeochemical mapping report
David Gray, a global leader in exploration hydrogeochemistry, is the lead author on the new CSIRO report and credited with assembling much of the national data.
"Over the past four years, Dr Gray has been getting whatever data he can on groundwater chemistry from all over Australia."
The data came from decades of CSIRO analysis, as well as the state government departments, the mining industry and universities. And it involved standardising information that came from more than 100 years of data collection.
"Dr Gray dealt with all the quality assurance and quality control issues to tie together around 320,000 data points on groundwater hydrogeochemistry from across Australia."
"As far as I'm aware, there's nothing of this magnitude anywhere else in the world," Dr Reid says.
Dr Wallace adds that there’s been a lot of goodwill between BoM, CSIRO and Geoscience Australia to make the Explorer and Atlases happen.
"We've all come to it with our unique expertise and worked together to create a national resource for the greater good."