Outgassing efficiency and atmopsheric composition should differ for mobile-lid and stagnant-lid planets

Kurzfassung

The long-term evolution of the atmospheres or rocky planets depends on several different factors, including (but not limited to) volcanic outgassing by partial melting of the rocky interior. Uprising melt may contain different assembladges of volatiles (CHONS) depending on the general mantle composition and redox state, the local volatile inventory, as well as melting depth. All these factors are assumed to vary for mobile-lid planets with an active surface recycling mechanism (e.g. plate tectonics or convective mobile resurfacing) when compared to stagnant-lid planets. In addition, the strength of volcanic activity varies for stagnant-lid and mobile-lid planets, with stronger activity and hence volcanic outgassing expected for the latter case. Atmospheres with pressures above Earth values also severely influence which volatiles will be further outgassed into the atmosphere depending on the solubility of the individual gas species. The outgassing fluxes therefore strongly depend on the evolution of the atmosphere, including atmosphere losses to space or by condensation or weathering. Ultimately, different atmospheric compositions will evolve for planets with low-pressure atmospheres (i.e. low-mass planets, planets without an active surface mobilization process, or planets with efficient atmosphere sinks/losses) and high-pressure atmospheres. Our studies allow us to predict ranges of likely atmospheric properties depending on planet mass and the surface mobility regime, that can then be compared to observations (i.e. with JWST or in the more distant future with the proposed LIFE mission).