New Insights into the Great Oxidation and Lomagundi Events

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The CLEVER Planets group at Rice University has published a new theory to explain the near simultaneous appearance of abundant oxygen in Earth’s atmosphere, the Great Oxidation Event, and an anomaly in carbon isotope ratios, the Lomagundi event. The scenario is centered on an increase in volcanic activity that occurred about 2.5 billion years ago, which led to a rapid increase in atmospheric CO2. These higher CO2 levels would have led to increased rainfall, which caused enhanced erosion on land, greater run-off and nutrients flowing into the ocean, enhanced burial of carbon in oceanic sediments, and an increase in photosynthesis (from the nutrients). The end result would have been an increase in oxygen in the atmosphere and an increase of carbon buried on the ocean floor and subducted into the mantle. The preferential storage of carbon-12 in the deep mantle and mobility of carbon-13 into nearby volcanic systems would result in a relative increase in carbon-13 into the atmosphere. The interaction between the atmosphere and the deep Earth provides important clues about the evolution of carbon and oxygen concentrations on Earth and other Earth-like planets. READ MORE