Rethinking the regolith

EXPLORATION under cover will be increasingly important in Australia in the coming years as near-surface deposits become more difficult to find. Research currently being conducted by CSIRO can provide tools to help explorers face this new challenge.
Rethinking the regolith Rethinking the regolith Rethinking the regolith Rethinking the regolith Rethinking the regolith


Exploration geochemist Dr David Gray is CSIRO's Exploration and Mining Division Regolith group leader, based at the Australian Resources Research Centre in Perth. He believes some of the work being done by him and his colleagues offer useful new techniques for explorers.

According to CSIRO, about 70% of Australia is concealed by regolith or transported sediments.

This regolith can mask mineralisation contained underneath or give misleading results, but it can also provide clues for explorers with the correct understanding of the chemical and physical processes of regolith formation.

One of the more interesting techniques CSIRO is working on, in conjunction with the Cooperative Research Centre for Landscapes, Environment and Mineral Exploration (CRC LEME) and a number of Australian universities, is the field of "phyto-exploration" - using surface vegetation to detect underlying mineralisation.

CRC LEME Mineral Exploration in Areas of Cover program leader Dr Ravi Anand explains how preliminary research has already shown that, in some cases, plants can offer clues to explorers about the mineralisation found in the bedrock. This research is now being extended through a large multi-sponsored project through AMIRA.

"Plant roots can go quite deep, particularly in summer when they're looking for water. As the roots pump water up, they also take low concentrations of metals to the surface," Anand said.

Metals such as gold, copper and zinc can be transported from the bedrock into the leaves and bark of a tree, giving explorers a glimpse to what might lie underneath.

Of course, it is not as simple as assaying a plant's leaves to find a gold deposit, as a variety of other factors including species, seasonal conditions, deposit type and environment all play a part in the success of the technique.

The group is about two years into a five-year program looking at biogeochemistry and has done work at Regis Resources' Moolart Well gold project and Jabiru Metals' Jaguar VMS base metals deposit, both in Western Australia, as well as other sites.

"We're certainly getting some promising results," Anand said.

"By applying these techniques, companies can improve their targeting and save valuable time and money when it comes to selecting potential drill targets."

CSIRO's work in biogeochemistry also has applications when it comes to the impact of mining on the environment.

For example, the technique can be used to demonstrate the levels of an element such as arsenic in vegetation before mining begins, protecting a company against accusations of environmental contamination should arsenic be discovered in the environment after mining begins.

Gray stressed that the group was aiming to develop robust biogeochemical techniques that are useful in certain ways in particular environments, making correct application of the techniques crucial for success.

CSIRO conducts a variety of industry funded research, runs training workshops for groups on request and conducts exploration seminars on a semi-regular basis.

Anyone who wants more information on the CSIRO Regolith Geoscience Program can contact Gray on (08) 6436 8678 or