Elucidating argon retention in high pressure silica phases.

The reactivity of noble gases at high pressures and temperatures is a broadening field, led mostly by the discovery of new xenon (Xe) compounds formed at extreme conditions. In the case of Xe oxides, P-induced covalent bonding occurs above 80 GPa for pure Xe-O compounds, while only a few GPa are necessary in silicates such as quartz with Xe as a minor element. We have started investigating Ar behaviour in planetary materials at high P-T conditions with the dual aim of understanding noble gases behaviour in planetary interiors, and opening new synthesis pathways for noble gases compounds. The objectives here are to elucidate the retention processes of Ar in C and SiO2 phases recovered from high P experiments by 1) identifying by X-ray fluorescence the Ar-rich zones in heterogeneous samples at the micron and sub-micron scale, and 2) by characterizing Ar-rich zones with X-ray absorption spectroscopy to identify Ar-host mineral(s) and/or new compounds, and describe Ar atomic environment.