Incorporation of Xenon in magmas at depth

Friday, 19 December 2014
Clémence Leroy, IMPMC Institut de Minéralogie et de Physique des Milieux Condensés, Paris Cedex 05, France, Chrystele Sanloup, University Pierre and Marie Curie Paris VI, Paris, France, Helene Bureau, CNRS, IMPMC, CNRS-UPMC Sorbonne Universites, Paris Cedex 16, France, Burkhard Schmidt, Georg-August-Universitaet Goettingen, Goettingen, Germany, Zuzana Konopkova, DESY Deutsches Elektronen Synchrotron, Hamburg, Germany and Caroline Raepsaet, CEA Commissariat à l'Energie Atomique Saclay, Gif-Sur-Yvette Cedex, France
Incorporation of volatile elements in magmas is enhanced at high pressure. The dissolved volatiles affect in turn the physical and chemical properties of silicate melts. Understanding volatiles incorporation in magmas and their effect on the melt’s structure can be approached by in situ characterizations such as X-ray diffraction or Raman spectroscopy.

Here, we focus on Xenon (Xe) in order to constrain its past and modern geochemical cycles. Indeed the 129I/129Xe extinct isotopic system is used to constrain planetary and atmosphere formation models. Moreover, some studies propose that Xe is currently recycled from the atmosphere to the mantle.

To study the solubility of Xe in silicate melts, we have performed in situ X-ray diffraction experiments on the synchrotron beam line P02 in PetraIII (DESY, Hamburg). Experiments were carried out using resistive heating diamond-anvil cells up to 7 GPa and 1300°C. Two compositions have been studied: a hydrous haplogranite (HPG) reference and a hydrous HPG doped with Xe. This composition is a magma analogue that is extremely well documented by petrological studies. Xenon can be identified on the radial distribution functions obtained by processing the x-ray diffraction data. Solubility mechanisms of Xe in silicate melts at depth will be discussed.