Fractionated Martian atmosphere in the nakhlites?

Considerable evidence points to a martian origin of the SNC meteorites. Noble gas isotopic compositions have been measured in most SNC meteorites. The ¹²⁹Xe/¹³²Xe vs. ⁸⁴Kr/¹³²Xe ratios in Chassigny, most shergottites, and lithology C of EETA 79001 define a linear array. This array is thought to be mixing line between martian mantle and martian atmosphere. One of the SNC meteorites, Nakhla contains a leachable component that has an elevated ¹²⁹Xe/¹³²Xe ratio relative to its ⁸⁴Kr/¹³²Xe ratio when compared to this approximately linear array. The elevated Xe isotopic ratio may represent a distinct reservoir in the martian crust or mantle. More plausibly, it is elementally fractioned martian atmosphere. -from Authors