Mars cryosphere: A potential reservoir for heavy noble gases?

► We explore the hypothesis that martian clathrates have sequestrated large amounts of Ar, Kr and Xe. ► We use a model predicting the clathrate composition formed from a CO2-dominated paleoatmosphere. ► We find that the presence of atmospheric SO2 does not affect the trapping of other minor species. ► We find that masses of Xe, Kr and Ar equivalent to those found on Earth can be trapped in clathrates. ► The proposed trapping mechanism could have played a major role in the shaping of the atmosphere.