Recreating Giants Impacts in the Laboratory: Shock Compression of MgSiO3 Bridgmanite to 14 Mbar

Abstract

Abstract Understanding giant impacts requires accurate description of how extreme pressures and temperatures affect the physical properties of the constituent materials. Here, we report shock experiments on two polymorphs of MgSiO 3: enstatite and bridgmanite (perovskite) crystals. We obtain pressure‐density shock equation of state to 14 Mbar and more than 9 g/cm 3, a 40% increase in density from previous data on MgSiO 3. Density‐functional‐theory molecular dynamics (DFT‐MD) simulations provide predictions for the shock Hugoniot curves for bridgmanite and enstatite and suggest that the Grüneisen parameter decreases with increasing density. The good agreement between the simulations and the experimental data, including for the shock temperature along the enstatite Hugoniot reveals that DFT‐MD simulations reproduce well the behavior of dense fluid MgSiO3. We also reveal a high optical reflectance indicative of a metal‐like electrical conductivity which supports the hypothesis that magma oceans may contribute to planetary magnetic field generation.

Keywords

• impact
• equation of state
• shockwaves
• magma ocean
• DFT
• MgSiO3