The Australian Academy of Sciences will tomorrow award CSIRO's Dr Bruce Hobbs the prestigious Jaeger Medal for "investigations of a high order into the solid earth or oceans of Australia."

Dr Hobbs is Deputy Chief Executive of CSIRO Minerals and Energy. Dr Hobbs and his team have spent over forty years investigating the geological mechanisms and processes in the earth's crust and mantle (lithosphere) that lead to the formation of ore bodies. It has been this recent work to incorporate these processes into a computer model that won him the Jaeger Medal.

"The model gives us enormous predictive power to help find the next Broken Hill or Mt Isa.

It takes a huge amount of guesswork out of exploration and can save mining companies millions of dollars," says Dr Hobbs.

"Deep under the earth, high temperatures and geological forces deform rocks creating the mountains, valleys and features familiar to us on earth," he says.

"When temperatures get high enough in the lithosphere and force is applied, the rocks don't break. Instead, they behave like plasticine or treacle and deform or flow. This action forces fluids, laden with dissolved metals, through the rocks.

"The chemistry of the fluid causes it to react with the surrounding rock precipitating out the metals. Changing temperatures and pressures or mixing with other fluids can have the same effect. Over time, the build up of precipitated metals forms the ore bodies that are the Holy Grail for mining and mineral exploration companies.

"In the last few years my research has taken this understanding of deformed rocks and the interactions occurring with temperature, pressure and the chemical reactions and linked them together in a computer model — a model now used by many mining companies and which has been important in understanding new exploration models for ore bodies such as those of Century Zinc and the Witwatersrand gold deposit."

The Jaeger medal recognizes the contribution of Professor John Conrad Jaeger to Australian earth science. Professor Jaeger was a fellow of the Australian Academy of Science and vice-president from 1958-59.

The presentation will occur at the Australian Academy of Sciences' Shine Dome, McCoy Cct, Acton. The presentations will begin at approximately 11:30am, following the Burnett Lecture.

More Information:

Dr Bruce Hobbs, CSIRO 0418 395 545

Shirley Winstanley, CSIRO Executive Assistant 08 9333 6730