Elucidating xenon bonding in phyllosilicate

Xenon (Xe), via its radiogenic isotopes, is a tracer of a variety of planetary processes as it is considered chemically inert and volatile. Retention of Xe in minerals has nonetheless been shown to occur by substitution to Si in quartz and olivine at depth, and consequent oxydation of Xe. Interestingly, Xe-doping of minerals considerably lowers the P-threshold of Xe bonding to O from 83 GPa in pure Xe-O system down to 1 GPa in more complex silicates. The goal here is to investigate if Xe chemistry in silicates can be extended to room P in phyllosilicates. This possibility would open the perspective to 1) understand Xe recycling from the atmosphere to the mantle via subduction of sedimentary phyllosilicates, and 2) resorb Xe gas released in the fuel of nuclear reactors. To reach these goals, we plan to probe Xe crystal-chemistry in cymrite, a high pressure phyllosilicate shown to retain up to 1 wt% Xe by measuring its X-ray absorption spectrum at the Xe K-edge.