Direct Observation of Shock-Induced Disordering of Enstatite Below the Melting Temperature

J. A. Hernandez, G. Morard, M. Guarguaglini, R. Alonso-Mori, A. Benuzzi-Mounaix, R. Bolis, G. Fiquet, E. Galtier, A. E. Gleason, S. Glenzer, F. Guyot, B. Ko, H. J. Lee, W. L. Mao, B. Nagler, N. Ozaki, A. K. Schuster, S. H. Shim, T. Vinci, A. Ravasio

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5 Scopus citations

Abstract

We report in situ structural measurements of shock-compressed single crystal orthoenstatite up to 337 ± 55 GPa on the Hugoniot, obtained by coupling ultrafast X-ray diffraction to laser-driven shock compression. Shock compression induces a disordering of the crystalline structure evidenced by the appearance of a diffuse X-ray diffraction signal at nanosecond timescales at 80 ± 13 GPa on the Hugoniot, well below the equilibrium melting pressure (>170 GPa). The formation of bridgmanite and post-perovskite have been indirectly reported in microsecond-scale plate-impact experiments. Therefore, we interpret the high-pressure disordered state we observed at nanosecond scale as an intermediate structure from which bridgmanite and post-perovskite crystallize at longer timescales. This evidence of a disordered structure of MgSiO3 on the Hugoniot indicates that the degree of polymerization of silicates is a key parameter to constrain the actual thermodynamics of shocks in natural environments.

Original languageEnglish (US)
Article numbere2020GL088887
JournalGeophysical Research Letters
Volume47
Issue number15
DOIs
StatePublished - Aug 16 2020

ASJC Scopus subject areas

  • Geophysics
  • Earth and Planetary Sciences(all)

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