Ocean Anoxic Event 1a:
A recent study, published in Science Advances, has provided new insights into the timing and duration of Ocean Anoxic Event 1a (OAE 1a).
- By studying prehistoric rocks and fossils from Mount Ashibetsu, Japan, researchers have pinpointed the causes and timeline of the OAE 1a that caused widespread oxygen depletion (anoxic) in Earth’s oceans.
- OAE 1a refers to a period during the Cretaceous Period (145 million years ago and ended 66 million years ago) when Earth’s oceans became depleted of oxygen, causing a significant disruption in marine life.
- The event is believed to have been triggered by massive volcanic eruptions that released significant amounts of carbon dioxide (CO₂), leading to global warming and oxygen depletion in the oceans, which subsequently resulted in the formation of anoxic marine basins.
- CO2 in seawater forms carbonic acid, dissolving sea creatures’ shells and lowering oxygen levels.
- This oxygen depletion led to the extinction of marine species, particularly plankton, and caused the formation of organic carbon-rich layers known as black shales.