title: Toward a mineral physics reference model for the Moon's core.
abstract: The physical properties of iron (Fe) at high pressure and high temperature are crucial for understanding the chemical composition, evolution, and dynamics of planetary interiors. Indeed, the inner structures of the telluric planets all share a similar layered nature: a central metallic core composed mostly of iron, surrounded by a silicate mantle, and a thin, chemically differentiated crust. To date, most studies of iron have focused on the hexagonal closed packed (hcp, or ε) phase, as ε-Fe is likely stable across the pressure and temperature conditions of Earth's core. However, at the more moderate pressures characteristic of the cores of smaller planetary bodies, such as the Moon, Mercury, or Mars, iron takes on a face-centered cubic (fcc, or γ) structure. Here we present compressional and shear wave sound velocity and density measurements of γ-Fe at high pressures and high temperatures, which are needed to develop accurate seismic models of planetary interiors. Our results indicate that the seismic velocities proposed for the Moon's inner core by a recent reanalysis of Apollo seismic data are well below those of γ-Fe. Our dataset thus provides strong constraints to seismic models of the lunar core and cores of small telluric planets. This allows us to propose a direct compositional and velocity model for the Moon's core.
authors.affiliation: Institut de Minéralogie, de Physique des Matériaux, et de Cosmochimie, UMR CNRS 7590, Sorbonne Universités - UPMC, Muséum National d'Histoire Naturelle, IRD Unité 206, 75252 Paris, France; daniele.antonangeli@impmc.upmc.fr.
authors.forename: Daniele
authors.initials: D
authors.lastname: Antonangeli
authors.affiliation: Institut de Minéralogie, de Physique des Matériaux, et de Cosmochimie, UMR CNRS 7590, Sorbonne Universités - UPMC, Muséum National d'Histoire Naturelle, IRD Unité 206, 75252 Paris, France;
authors.forename: Guillaume
authors.initials: G
authors.lastname: Morard
authors.affiliation: Department of Geology, University of Maryland, College Park, MD 20742;
authors.forename: Nicholas C
authors.initials: NC
authors.lastname: Schmerr
authors.affiliation: Department of Earth and Planetary Sciences, Tokyo Institute of Technology, Tokyo 152-8551, Japan;
authors.forename: Tetsuya
authors.initials: T
authors.lastname: Komabayashi
authors.affiliation: European Synchrotron Radiation Facility, 38043 Grenoble Cedex, France; and.
authors.forename: Michael
authors.initials: M
authors.lastname: Krisch
authors.affiliation: Institut de Minéralogie, de Physique des Matériaux, et de Cosmochimie, UMR CNRS 7590, Sorbonne Universités - UPMC, Muséum National d'Histoire Naturelle, IRD Unité 206, 75252 Paris, France;
authors.forename: Guillaume
authors.initials: G
authors.lastname: Fiquet
authors.affiliation: Geophysical Laboratory, Carnegie Institution of Washington, Washington, DC 20015.
authors.forename: Yingwei
authors.initials: Y
authors.lastname: Fei
keywords: Moon; high pressure; high temperature; iron; telluric planetary cores