Study Identifies Cold Subduction as Key Driver of Earth's Oxygen-Rich Atmosphere
A recent study published in the Proceedings of the National Academy of Sciences suggests that cold subduction, a tectonic process where cool oceanic plates sink into Earth's mantle, played a significant role in the development of Earth's oxygen-rich atmosphere. Historically, Earth was mostly devoid of oxygen until certain geological processes allowed for its accumulation. The study identifies three major oxygenation events: the Great Oxygenation Event (GOE), the Neoproterozoic Oxygenation Event (NOE), and the Paleozoic Oxygenation Event (POE). These events were crucial in enabling complex life on Earth. The researchers propose that cold subduction enhanced the sinking of organic carbon and pyrite into the mantle, reducing oxygen sinks and allowing atmospheric oxygen levels to rise. By constructing a time series of metamorphic ratios of temperature and pressure, the study aligns these geological changes with the historical oxygenation events. 
