Part of the Paleoproterozoic Era
Siderian Period - Oxygenian Period - Jatulian Period
The Oxygenian Period is the first period of the Paleoproterozoic Era and of the Proterozoic Eon. The Oxygenian begins at the time from which the oldest glacial deposits are known and ends at the time from which breakout magmatism is first known. The Oxygenian gets its name from the Great Oxygenation event, otherwise known as the Oxygen Catastrophe. Anaerobic algae had been releasing oxygen into the air through oxygenic photosynthesis. However, with aerobic organisms still rare, there was a major buildup of oxygen in the atmosphere, leading to a mass extinction of anaerobic organisms, and leaving aerobic organisms as the dominant forms of life on the planet. The Huronian glaciation began during this period at around 2400 MYA, coinciding with the Great Oxygenation, and would continue into the Jatulian Period.
The Oxygenian is not further subdivided into epochs.
Oxygenian Timescale:
Oxygenian Period - 2420-2250