SiO2 Glass Density to Lower-Mantle Pressures

Research output: Research - peer-reviewJournal article – Annual report year: 2017

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DOI

  • Author: Petitgirard, Sylvain

    University of Bayreuth

  • Author: Malfait, Wim J.

    Swiss Federal Laboratories for Materials Science and Technology (Empa)

  • Author: Journaux, Baptiste

    Universite Grenoble Alpes

  • Author: Collings, Ines E.

    University of Bayreuth

  • Author: Jennings, Eleanor S.

    University of Bayreuth

  • Author: Blanchard, Ingrid

    University of Bayreuth

  • Author: Kantor, Innokenty

    Neutrons and X-rays for Materials Physics, Department of Physics, Technical University of Denmark, Fysikvej, 2800, Kgs. Lyngby, Denmark

  • Author: Kurnosov, Alexander

    University of Bayreuth

  • Author: Cotte, Marine

    Sorbonne Universités

  • Author: Dane, Thomas

    European Synchrotron Radiation Facility

  • Author: Burghammer, Manfred

    European Synchrotron Radiation Facility

  • Author: Rubie, David C.

    University of Bayreuth

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The convection or settling of matter in the deep Earth's interior is mostly constrained by density variations between the different reservoirs. Knowledge of the density contrast between solid and molten silicates is thus of prime importance to understand and model the dynamic behavior of the past and present Earth. SiO2 is the main constituent of Earth's mantle and is the reference model system for the behavior of silicate melts at high pressure. Here, we apply our recently developed x-ray absorption technique to the density of SiO2 glass up to 110 GPa, doubling the pressure range for such measurements. Our density data validate recent molecular dynamics simulations and are in good agreement with previous experimental studies conducted at lower pressure. Silica glass rapidly densifies up to 40 GPa, but the density trend then flattens to become asymptotic to the density of SiO2 minerals above 60 GPa. The density data present two discontinuities at similar to 17 and similar to 60 GPa that can be related to a silicon coordination increase from 4 to a mixed 5/6 coordination and from 5/6 to sixfold, respectively. SiO2 glass becomes denser than MgSiO3 glass at similar to 40 GPa, and its density becomes identical to that of MgSiO3 glass above 80 GPa. Our results on SiO2 glass may suggest that a variation of SiO2 content in a basaltic or pyrolitic melt with pressure has at most a minor effect on the final melt density, and iron partitioning between the melts and residual solids is the predominant factor that controls melt buoyancy in the lowermost mantle.
Original languageEnglish
Article number215701
JournalPhysical Review Letters
Volume119
Issue number21
Number of pages6
ISSN0031-9007
DOIs
StatePublished - 2017

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© 2017 American Physical Society

CitationsWeb of Science® Times Cited: 3
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