A NEW FE-CARBONATE FORMATION WINDOW ON MARS
Résumé
In this study, we focus on modeling results based on a kinetic weathering experimental setup under Mars-like conditions. With these models, we aim to enhance our ability to interpret the redox and hydrological conditions when finding Fe-oxides or carbonates on Mars. We determined a new Fe-carbonate formation window, even under oxidizing conditions from a thermodynamic standpoint, redefining the significance of “reducing” or “oxidizing” conditions on Mars. Additionally, because of the different residence time required to form Fe-oxides and Fe-carbonate, we interpret that Fe-carbonate would be primarily a clue for a different hydrological regime (chemical sedimentation or higher weathering rates) and only then a redox marker. At a global scale, the formation of authigenic siderite and even other carbonates (for example, when accounting the Mg-inhibition of calcite precipitation) during rock weathering would be rather limited without long residence times or later evaporation.
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