Mineral Alteration in Water-Saturated Liquid CO2 on Early Mars

Liquid CO2 was likely present at various places and times in martian history, at least in the subsurface, and liquid CO2 floods have been suggested in the literature to explain morphological features ranging from small gullies to massive valley networks. This paper adds two important aspects to that discussion. First, extensive research into liquid CO2 sequestration on Earth has revealed remarkable chemical activity if the liquid is water-saturated, as it would likely have been on Mars. Second, it is plausible that surface liquid CO2 was stable in some regions on early Mars if atmospheric pressure exceeded 5.18 bar. In some cases, single-episode liquid CO2 reactions can result in rapid and copious production of altered minerals that would require multiple episodes in different aqueous pH environments to explain in a liquid water paradigm.