Sound velocity and density of magnesiowüstites: Implications for ultralow‐velocity zone topography

Abstract

Abstract We explore the effect of Mg/Fe substitution on the sound velocities of iron‐rich (Mg 1 − x Fe x )O, where x = 0.84, 0.94, and 1.0. Sound velocities were determined using nuclear resonance inelastic X‐ray scattering as a function of pressure, approaching those of the lowermost mantle. The systematics of cation substitution in the Fe‐rich limit has the potential to play an important role in the interpretation of seismic observations of the core‐mantle boundary. By determining a relationship between sound velocity, density, and composition of (Mg,Fe)O, this study explores the potential constraints on ultralow‐velocity zones at the core‐mantle boundary.