The joining of the Earth’s continents may have been a driving factor in the oxygenation of Earth, reports a study published online this week in Nature Geoscience. The formation of supercontinents ? such as Pangaea ? could have had a direct effect on the rising levels of oxygen in the atmosphere, from almost nothing at the dawn of the Earth to 20% now.
Ian Campbell and Charlotte Allen compared reconstructions of atmospheric oxygen levels throughout the Earth’s history to the timing of supercontinent formation, and found that the six major jumps in atmospheric oxygen concentration coincided with the amalgamation of supercontinents. The team suggests that when the individual continents collided, large mountain chains arose. As these super-mountains eroded, they released nutrients into the oceans, stimulating the growth of oxygen-producing phytoplankton and bacteria. Subsequent burial of organic carbon by sediments carried into the oceans from the mountains allowed atmospheric oxygen levels to rise unchecked.
Although the increased production of oxygen ceased when the super-mountains were completely eroded, the higher atmospheric oxygen levels persisted.