Scientists discover why world’s richest ore deposits were formed reports that a team of scientists from the University of Tasmania and University of California, led by Emeritus Professor Ross Large from the ARC Centre of Excellence in Ore Deposits (CODES), has shown that the rise of oxygen in the atmosphere 2.3 to 1.8 billion years ago caused not only a change in the evolution of life, but also a dramatic shift from the formation of iron, gold and nickel ore deposits to zinc, silver, copper and uranium ore deposits.