Led by Emeritus Professor Ross Large from the ARC Centre of Excellence in Ore Deposits (CODES), researchers from the University of Tasmania, in collaboration with their University of California counterparts, have discovered when and why some of the richest ore deposits on the planet were formed.

The team recorded subtle changes in the level of oxygen in the Earth’s ancient atmosphere using a laser-based analytical technology developed in the University of Tasmania laboratories. Their fundamental research provides a clearer understanding of how oxygen changed in the ancient atmosphere, and how this relates to the generation of large and rich ore deposits in ancient rocks.

Their research revealed that when oxygen levels were very low in the atmosphere and oceans, giant ore deposits of gold, iron and nickel formed in the oldest (Archean) rocks. Then, following the Great Oxygenation Event (about two billion years ago), when oxygen levels significantly increased, there was a switch to giant deposits of copper,zinc, silver and uranium. Some of Australia’s biggest and richest ore deposits at Broken Hill (zinc-lead-silver), Olympic Dam (copper-uranium), Ranger (uranium) and Mt Isa (copper-zinc-lead-silver) formed after this switch.

These fundamental research findings enable the ups and downs of oxygen in the past atmosphere to be precisely determined to predict the times in geological history when and where other giant ore deposits may have formed in Australia. This will assist geologists in the discovery of rich deposits of copper, zinc and uranium.

Professor Ross Large, former ARC Centre Director, and his team from the ARC Centre of Excellence in Ore Deposits at the University of Tasmania,along with collaborating institutions, received the UNSW Eureka Prize for Excellence in Interdisciplinary Scientific Research for the Trace Elements in Past Oceans (TEPO) project

Image: Professor Ross Large.
Image courtesy: Karen Brown / University of Tasmania.