Volatile and Trace Element Storage in a Crystallizing Martian Magma Ocean. / Hier-Majumder, Saswata; hirschmann, Marc.

In: Earth and Planetary Science Letters, 2020.

Research output: Contribution to journalArticle

Submitted

Abstract

Immediately following metal-silicate segregation in Mars, the planet underwent a magma ocean (MO) phase. During crystallization of the MO, volatiles such as CO2 and H2O played a crucial role by creating a greenhouse primitive atmosphere (PA) and inhibiting radiating heat loss from the young planet. Two important aspects of this coupled evolution are, the dynamics of melt trapping in the freezing front of the residual mantle (RM) and the oxidation state of the martian interior during crystallization. In this work, we investigate the influence of both in the evolution of the martian MO. We show that the H2O content of the martian RM is strongly influenced by dynamic melt trapping, and may reach up to 1200 ppmw (micrograms/gram). The mantle H2O content, $C^{RM}_{H2O}$, is related to the height $h$ of a Global Equivalent Layer (GEL) of water in bulk Mars by C^{RM}_{H2O} (ppmw) = 0.138 h (m). We also show that the redox state of the MO exerts a strong control on the total CO2 content of the RM and the time of crystallization. Under the most reducing conditions we examined, the residual mantle can sequester up to 1100 ppmw CO2 in the form of trapped carbonate melt and solid carbon. Overall, dynamic melt trapping exerts a stronger influence on the mantle H2O, K, Rb, Ba, Th, and U concentrations while the redox condition impacts the mantle C content more strongly.
Original languageEnglish
JournalEarth and Planetary Science Letters
Publication statusSubmitted - 2020

ID: 36676070