Redox Evolution of the Crystallizing Terrestrial Magma Ocean and Its Influence on the Outgassed Atmosphere

Abstract Magma oceans (MOs) are episodes of large-scale melting the mantle terrestrial planets. The energy delivered by Moon-forming impact induced a deep MO on young Earth, corresponding to last episode core-mantle equilibration. crystallization this led outgassing volatiles initially present in Earth’s mantle, resulting formation secondary atmosphere. During outgassing, acts as chemical buffer for atmosphere via oxygen fugacity, set equilibrium between ferrous- and ferric-iron oxides silicate melts. By tracking evolution fugacity during solidification, we model evolving composition C-O-H We use atmospheric calculate its thermal structure radiative flux. This allows us lifetime MO. find that, upon crystallizing, evolves from mildly reducing highly oxidized redox state, thereby transiting CO- H 2 -dominated CO - O-dominated one. overall duration depend mostly bulk content remain below 1.5 millions yr up nine water oceans’ worth H. Our also suggests that reduced atmospheres emit lower infrared radiation than ones, despite greenhouse effect species, longer former case. Although developed framework applies all planet exoplanet MOs, depending their volatile budgets.