Ancient Martian carbon may be buried rather than lost to space, with a new study pointing to feldspar-rich rocks as a hidden reservoir for the CO2 once thought missing.
1D thermochemical simulations of cold, water-rock reactions showed feldspar-rich crust naturally forms calcium/iron-rich carbonates, while mafic rocks more often yield magnesium-rich carbonates after longer alteration.
Groundwater flow emerged as a key mechanism: it created carbonates efficiently but also dissolved near-surface minerals and carried carbon-bearing material deeper underground, helping explain Mars' sparse surface carbonate record.
More than 3 billion years after Mars likely had a thicker CO2 atmosphere and intermittent liquid water, the findings give future drilling and rover missions new subsurface targets to test the planet's climate history.