What was the Neoproterozoic oxygenation event?

The Neoproterozoic Oxygenation Event was a major geologic time interval between roughly 850 and 540 million years ago when atmospheric and oceanic oxygen concentrations rose significantly. Taking place after a long low-oxygen period called the Boring Billion, it saw oxygen levels potentially rise above 13 percent of modern levels and eventually reach present levels or higher. This event marked the second major oxygen increase in Earth history, following the Great Oxidation Event.

What we know

• The Neoproterozoic Oxygenation Event occurred between approximately 850 and 540 million years ago, representing the second major increase in Earth's atmospheric and oceanic oxygen concentration. [1, 2]
• Before the event, atmospheric oxygen concentration stayed below 0.1 percent of present levels throughout most of the early and mid-Proterozoic during a prolonged period of extremely low oxygen. [2, 5]
• Oxygen concentrations rose to greater than 13 percent of modern levels in the early Neoproterozoic and potentially up to roughly 50 percent during the Cryogenian Sturtian-Marinoan interglacial. [2]

Still open

• It remains unclear whether the Neoproterozoic Oxygenation Event was a synchronous, global event or a series of asynchronous, regional oxygenation intervals with unrelated causes.

Where to go next

• compared withWhat caused the Great Oxidation Event?
• whenHow did Snowball Earth affect the Neoproterozoic era?
• the bigger pictureWhat was the Boring Billion in Earth history?
• what followedHow did early complex life evolve during the Neoproterozoic?
• how it workedWhat role did the Pan-African orogeny play in continental crust formation?
• an unexpected connectionHow does primitive sponge evolution link to ancient oxygen surges?The earliest fossils of complex life, such as the primitive sponge Otavia, emerge right out of the Tonian period during this expansive timeline of atmospheric change.

Sources

• [1]Neoproterozoic oxygenation event (Wikidata Q115824268) · CC0 1.0
• [2]Neoproterozoic oxygenation event · CC BY-SA 4.0
• [3]Great Oxidation Event · CC BY-SA 4.0
• [4]Neoproterozoic · CC BY-SA 4.0
• [5]Geological history of oxygen · CC BY-SA 4.0