Great Oxidation Event Contradiction Explained

Using computer models, scientists find that the amount of oxygen in Earth’s atmosphere prior to the Great Oxidation Event was too small to be detected in rocks.

IMAGE: Artist’s rendition of what the Earth could have looked like in the Archean Eon, from 4 billion to 2.5 billion years ago. CREDIT: Peter Sawyer/Smithsonian Institution

Earth hasn’t always been a habitable planet, at least not for life as we currently know it. Then about 2.4 billion years ago, something changed. That something is called the Great Oxidation Event, where global oxygen levels rose significantly, and it radically transformed both our atmosphere and our biosphere, making the diversity of life we have now possible.

And this event has always been something of a mystery because the evidence has contradictions. Now, in a new paper published in Science Advances, a team of scientists lays out how they may have solved the contradictions.

First off, some scientists argue that since we’ve not found evidence of oxygen in the rock record dating back to before the Great Oxidation Event, it must not have been there. But on the other hand, recent work has shown that some common minerals will vigorously react and break down in the presence of oxygen, and those reactions allow minerals like molybdenum to accumulate in rivers and oceans, which we have found in the rock record prior to the event. That’s confusing, to say the…