EGU21-10847
https://doi.org/10.5194/egusphere-egu21-10847
EGU General Assembly 2021
© Author(s) 2021. This work is distributed under
the Creative Commons Attribution 4.0 License.

The vaporization behavior of carbon and hydrogen from the early global magma ocean

Natalia Solomatova1 and Razvan Caracas2
Natalia Solomatova and Razvan Caracas
  • 1CNRS, ENS de Lyon, Laboratoire de Géologie de Lyon UMR 5276, France (natalia.solomatova@ens-lyon.fr)
  • 2The Center for Earth Evolution and Dynamics (CEED), University of Oslo, Blindern, Oslo, Norway (razvan.caracas@ens-lyon.fr)

Estimating the fluxes and speciation of volatiles during the existence of a global magma ocean is fundamental for understanding the cooling history of the early Earth and for quantifying the volatile budget of the present day. Using first-principles molecular dynamics, we predict the vaporization rate of carbon and hydrogen at the interface between the magma ocean and the hot dense atmosphere, just after the Moon-forming impact. The concentration of carbon and the oxidation state of the melts affect the speciation of the vaporized carbon molecules (e.g., the ratio of carbon dioxide to carbon monoxide), but do not appear to affect the overall volatility of carbon. We find that carbon is rapidly devolatilized even under pressure, while hydrogen remains mostly dissolved in the melt during the devolatilization process of carbon. Thus, in the early stages of the global magma ocean, significantly more carbon than hydrogen would have been released into the atmosphere, and it is only after the atmospheric pressure decreased, that much of the hydrogen devolatilized from the melt. At temperatures of 5000 K (and above), we predict that bubbles in the magma ocean contained a significant fraction of silicate vapor, increasing with decreasing depths with the growth of the bubbles, affecting the transport and rheological properties of the magma ocean. As the temperature cooled, the silicate species condensed back into the magma ocean, leaving highly volatile atmophile species, such as CO2 and H2O, as the dominant species in the atmosphere. Due to the greenhouse nature of CO2, its concentration in the atmosphere would have had a considerable effect on the cooling rate of the early Earth.

How to cite: Solomatova, N. and Caracas, R.: The vaporization behavior of carbon and hydrogen from the early global magma ocean, EGU General Assembly 2021, online, 19–30 Apr 2021, EGU21-10847, https://doi.org/10.5194/egusphere-egu21-10847, 2021.