Dynamic compression of hydrated silicate glasses

In the canonical view of terrestrial planet formation, planets lose volatile atomic species (including water) through the violent processes of planetary formation. Geophysical and astronomical studies have shown, however, that volatile elements can be retained throughout the planetary lifecycle. Determining the mechanisms that permit retention during planetary creation and destruction requires experimental data on compressibility of both hydrous and anhydrous silicate melts at relevant pressures and temperatures. Measurements on solid amorphous silicate glasses can also provide insight to the behavior of molten silicates because both states exhibit anomalous behavior thought to arise from similar mechanisms. We will present a selection of results from analyses of previous and ongoing dynamic compression experiments on SiO₂, MgSiO₃, and borosilicate glasses containing various concentrations of H₂O or OH^- and subjected to various loading paths — ramp compression to 10-30 GPa (using the Thor pulsed-power driver), shock-melt-ramp compression from 100-130 GPa initial shock state to 200+ GPa (using the Z Machine), and shock-release from shock states up to 200 GPa (using both the STAR two-stage gun and the Z Machine) — with molecular dynamics calculations to aid interpretation.