Elasticity of silicate glasses along the MgSiO3-FeAlO3 join

Abstract The density and elastic properties of silicate melts are critical for understanding planetary differentiation and magma ocean dynamics. In this study, we measured the elastic properties of MgSiO3-FeAlO3 glasses with varying FeAlO3 contents (0–40 mol%), which we use as room-temperature analogs for planetary magma ocean melts, to elucidate the effects of Fe and Al on the melt elasticity, density, and viscosity. With increasing FeAlO3 content, glass density and elastic moduli increase, while acoustic velocities decrease. The lower molar volumes observed in Fe-rich glasses are consistent with enhanced elastic modulus and polymerization. We also found that normalized compressibility –(∂V/∂P)S increases linearly with the non-bridging oxygen per tetrahedral cation (NBO/T) but decreases with increasing FeAlO3 content. These results demonstrate that variations in glass composition, particularly FeAlO3 content, exert a strong control on physical properties and indicate that analogous compositional effects likely occur in silicate melts, with significant consequences for magma ocean crystallization dynamics.