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Title: Olivine alteration and the loss of Mars’ early atmospheric carbon
The early Martian atmosphere had 0.25 to 4 bar of CO2but thinned rapidly around 3.5 billion years ago. The fate of that carbon remains poorly constrained. The hydrothermal alteration of ultramafic rocks, rich in Fe(II) and Mg, forms both abiotic methane, serpentine, and high-surface-area smectite clays. Given the abundance of ultramafic rocks and smectite in the Martian upper crust and the growing evidence of organic carbon in Martian sedimentary rocks, we quantify the effects of ultramafic alteration on the carbon cycle of early Mars. We calculate the capacity of Noachian-age clays to store organic carbon. Up to 1.7 bar of CO2can plausibly be adsorbed on clay surfaces. Coupling abiotic methanogenesis with best estimates of Mars’ δ13C history predicts a reservoir of 0.6 to 1.3 bar of CO2equivalent. Such a reservoir could be used as an energy source for long-term missions. Our results further illustrate the control of water-rock reactions on the atmospheric evolution of planets.  more » « less
Award ID(s):
1925863
PAR ID:
10575722
Author(s) / Creator(s):
;
Publisher / Repository:
Science Advances
Date Published:
Journal Name:
Science Advances
Volume:
10
Issue:
39
ISSN:
2375-2548
Format(s):
Medium: X
Sponsoring Org:
National Science Foundation
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