A multi-faceted experimental study on the dynamic behavior of MgSiO₃ glass in the Earth's deep interior

Pressure-induced structural modifications in silicate melts play a crucial role in controlling dynamic processes in the deep interiors of the Earth and other planets. The correlation between structural and macroscopic properties of silicate liquids (densification, viscosity, chemical differentiation, etc.), however, remains poorly understood. Here we report the evolution of structural modifications and elastic properties of MgSiO3 glass to pressures up to similar to 70 GPa using a combination of experimental techniques, including micro-confocal Raman spectroscopy, angle-dispersive X-ray scattering, and Brillouin spectroscopy in the diamond-anvil cell. Our combined data set provides consistent and complementary evidence of a series of pressure-induced structural modifications in MgSiO3 glass at similar to 2, similar to 8, similar to 20, and similar to 40 GPa. Based on these results, a structural evolution model for MgSiO3 glass is proposed. We also discuss the role of Mg-O component in MgSiO3 and Mg2SiO4 glasses in controlling pressure-induced structural modifications and mechanical responses in these supercooled liquids.