Geologists from Trinity College Dublin have rewritten evolutionary history by finding that oxygen-producing life forms were present on Earth some three billion years ago – 60 million years earlier than previously thought.
Working with colleagues from the Presidency University in Kolkata, India, the geologists found evidence for chemical weathering of rocks leading to soil formation that occurred in the presence of O2. Using the naturally occurring uranium-lead isotope decay system, which is used for age determinations on geological time-scales, the scientists deduced that these events took place at least 3.02 billion years ago. The ancient soil (or paleosol) came from the Singhbhum Craton of Odisha (pictured above), and was named the ‘Keonjhar Paleosol’ after the nearest local town.
Trinity Professor Quentin Crowley commented on the discovery saying, “Our research gives further credence to the notion of early and short-lived atmospheric oxygenation. This particular example is the oldest known example of oxidative weathering from a terrestrial environment, occurring about 600 million years before the Great Oxidation Event that laid the foundations for the evolution of complex life.”