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Modeling the Rise of Cyanobacteria in Earth’s early History
We develop a mathematical model to predict the evolution of atmospheric O2 in the Late Archean and Early Proterozoic. Change in atmospheric partial pressure of O2 (pO2) between 2.7 and 1.8 Ga, a period during which pO2 crossed the threshold of 1% of the present atmospheric level, is estimated by balancing the production (burial of photosynthetic organic carbon and pyrite in sedimentary rocks) and consumption fluxes of O2. Rates of burial and oxidative weathering of organic matter and pyrite in sedimentary rocks are calculated using the isotope mass balance method; rate of oxidation of hydrothermal iron is determined based on ocean circulation. The primary objective of this study is to set an upper limit for atmospheric pO2 during the period of 2.7–1.8 Ga, which affects the complexity of organisms inhabiting the Earth by the late Early Proterozoic.
