Before the origin of life, Earth’s atmosphere was built up by outgassing of the mantle. In my group, we model how C-O-H outgassing evolved through the early Archean if global plate tectonics had not yet initiated and all outgassing was subaerial. The model couples numerical mantle convection, redox partitioning in the melt, and volatile chemical speciation. We show that the mantle oxidation state is the dominant control on outgassing fluxes, more so than the initial volatile content or thermal state. The oxidation state affects both the volatile speciation and the carbon partitioning in the melt.
I will discuss implications for early Earth’s outgassing fluxes, and then give a broader perspective on redox-dependent atmosphere diversity for rocky planets in general (also beyond the solar system) including observational possibilities.