Ocean Anoxic Event 1a (OAE 1a)
Ocean Anoxic Event 1a (OAE 1a) occurred 119.5 million years ago, causing widespread marine extinctions due to low oxygen levels. Likely triggered by massive volcanic eruptions, such as those from the Ontong Java Nui complex, it released large amounts of CO₂, warming the planet and disrupting marine ecosystems. The event lasted 1.1 million years and drastically affected plankton populations. Researchers analyzed volcanic ash layers on Hokkaido Island, Japan, using isotope studies to link the event with global volcanic activity. This discovery highlights the impacts of ancient climate disruptions and improves understanding of Earth’s geological and biological history.
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