Volatile chemical speciation and atmosphere evolution during the Earth magma ocean

Kurzfassung

During its early stage the Earth was likely characterized by a magma ocean period. The focus of the present research is an investigation of the magma ocean volatile outgassing and the related evolution of the early atmosphere. We analyse the chemical speciation of the C-O-H system and its in influence in the atmosphere chemical composition. The volatile chemical speciation of the C-O-H system is analysed with the equilibrium and mass balance method. Since the gas chemical composition is affected by the volatile availability of the magma ocean and by the melt oxygen fugacity, this method shows the direct link between the interior and the development of the atmosphere. We observed that under reduced condition (QIF and IW mineral buffers) the dominant outgassed gas phases are H2 and CO. On the other hand, with an oxidizing ambient (NiNiO and QIF mineral buffers) the principal gas phases are H2O and CO2. The structure and the evolution of the atmosphere are investigated by calculating the outgoing longwave radiation at the top of the atmosphere using the line-by-line radiative transfer code GARLIC. The results collected show the strong change in the volatile composition due to the redox condition and to the temperature. The chemical composition of the outgassed volatile influence both the atmosphere development and the cooling rate of the entire planet. The analytical technique shows the potential to investigate also the atmosphere and the thermal evolution of solid exoplanets.