Abstract
The atmosphere and oceans became oxidized across two main transitional periods, the Great Oxidation Event (~2.45 and 2.2 Ga) and the Neoproterozoic Oxidation Event (~0.80 and 0.54 Ga). Pieces of evidence are found in South Africa, North America, Western Australia and Russia, but the real timing, duration, mechanism and range of O2 increase are still unsolved question due to poor age const…