The shock Hugoniot of Fe-free and Fe-bearing enstatite to 1.7 TPa

ORAL

Abstract

Polymorphs of MgSiO3 are the most abundant minerals in the Earth and are common components of other terrestrial planets. How these minerals behave under extreme conditions can inform us of the processes of planet formation and the dynamics of planetary interiors. Here, we extend the shock Hugoniot of Fe-free enstatite to 1700 GPa and we present the first shock compression and shock temperature data of Fe-bearing enstatite ((Mg0.9,Fe0.1)SiO3, bronzite) between 200 and 1600 GPa. We find that adding Fe to the enstatite system makes the silicate liquids more compressible at relatively low-pressures, but that these fluids stiffen rapidly at higher pressures. Somewhat surprisingly, despite the differences in compressibility, the shock temperatures for Fe-free and Fe-bearing enstatite are identical within error, suggesting some compensating effects in the heat capacity of these materials. These data will be used to inform models of giant impacts for planets with more realistic chemical compositions.

*Approved for release LA-UR-25-21078, SAND2025-01542A. Shots were awarded through the Laboratory Basic Science program under the auspices of the U.S. DOE/NNSA by the University of Rochester's LLE under Contract DE-NA0003856. Part of this work was prepared by LLNL under Contract DE-AC52-07NA27344 with partial support from LDRD project 19-ERD-031. This work was supported in part by the UC Office of the President (LFR-17-449059) and the UC Center for Matter under Extreme Conditions (CMEC) under the DOE/NNSA under Award Number DE-NA0003842. Experiments at the Z Machine were awarded through the Z-Fundamental Science Program and DE-NA0003904. Sandia National Laboratories is managed and operated by National Technology and Engineering Solutions of Sandia LLC, a wholly owned subsidiary of Honeywell International Inc. for the U.S. DOE/NNSA under contract DE-NA0003525. This work was supported by the U.S. DOE through the Los Alamos National Laboratory. Los Alamos National Laboratory is operated by Triad National Security, LLC, for the National Nuclear Security Administration of U.S. Department of Energy (Contract No. 89233218CNA000001).

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Presenters

  • Bethany A Chidester

    • Los Alamos National Laboratory (LANL)

Authors

  • Bethany A Chidester

    • Los Alamos National Laboratory (LANL)

  • Marius Millot

    • Lawrence Livermore National Laboratory

  • Kaitlyn M Amodeo

    • Sandia National Laboratories

  • Dylan K Spaulding

    • Union of Concerned Scientists

  • David E Bliss

    • Sandia National Laboratories

  • Pat Kalita

    • Sandia National Laboratories

  • Seth Root

    • Sandia National Laboratories

  • Dayne E Fratanduono

    • Lawrence Livermore National Laboratory

  • Sarah Toby Stewart

    • Arizona State University

  • Stein B Jacobsen

    • Harvard