Carbonate rocks deep underground may explain Mars' missing water

JAXA-led simulations show feldspar-rich Martian rocks readily form calcium-iron carbonates, while groundwater dissolves them near the surface and reprecipitates them deeper. This could explain the scarcity of surface carbonates and point to buried water and carbonate stores.

• Feldspar-rich rocks produce calcium-iron carbonates under most conditions
• Mafic rocks form carbonates only briefly before shifting to magnesium-rich ones
• Percolating groundwater forms carbonates far more efficiently than standing water
• Carbonates dissolve near the surface and reprecipitate deeper underground