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- Title
Inhibition of carbonate synthesis in acidic oceans on early Mars.
- Authors
Fairén, Alberto G; Fernández-Remolar, David; Dohm, James M; Baker, Victor R; Amils, Ricardo
- Abstract
Several lines of evidence have recently reinforced the hypothesis that an ocean existed on early Mars. Carbonates are accordingly expected to have formed from oceanic sedimentation of carbon dioxide from the ancient martian atmosphere. But spectral imaging of the martian surface has revealed the presence of only a small amount of carbonate, widely distributed in the martian dust. Here we examine the feasibility of carbonate synthesis in ancient martian oceans using aqueous equilibrium calculations. We show that partial pressures of atmospheric carbon dioxide in the range 0.8-4 bar, in the presence of up to 13.5 mM sulphate and 0.8 mM iron in sea water, result in an acidic oceanic environment with a pH of less than 6.2. This precludes the formation of siderite, usually expected to be the first major carbonate mineral to precipitate. We conclude that extensive interaction between an atmosphere dominated by carbon dioxide and a lasting sulphate- and iron-enriched acidic ocean on early Mars is a plausible explanation for the observed absence of carbonates.
- Publication
Nature, 2004, Vol 431, Issue 7007, p423
- ISSN
1476-4687
- Publication type
Journal Article
- DOI
10.1038/nature02911