 Great Oxidation Event

archean/proterozoic barrier.

The Great Oxidation Event (GOE), also known as the Great Oxidation or the Oxygenation Event, refers to a significant increase in Earth's atmospheric oxygen levels that occurred approximately 2.4 billion years ago, during the Paleoproterozoic Era. This event marked a major turning point in Earth's history and is associated with the emergence of oxygen-producing photosynthetic organisms, primarily cyanobacteria.