Investigating shock-metamorphism in meteor impacts via high pressure-temperature experiments on SiO2

Silicates can be exposed to extreme pressures and temperatures in laboratory settings to mimic collisions between planetary bodies. We have conducted laser shock experiments on both single crystal quartz and polycrystalline quartzite at Omega Laser Laboratory, Rochester, NY using the Omega-60 Laser to reach peak pressures of 40 GPa. The behavior of quartz and quartzite under shock-compression provides insight into phase transition kinetics and grain growth, enabling better constraints on the properties of the surface and shallow subsurface of planetary bodies following meteorite impacts. Raman and X-ray diffraction data collected from the recovered, shocked samples indicate phase evolution of SiO₂ at high pressures and temperatures comparable to those of impact conditions. A map of pressure-temperature-phase-time during the passage of a shock in a sample was collected by overlaying a 20 um× 20 um grid pattern to examine phase (as determined via Raman and micro-XRD) as a function of distance from the initial shock penetration point (as seen in optical microscopy). The distance from the sample crater to the gridded section of interest was then correlated with the shock speed as determined by the silica Hugoniot to determine the time that it takes to form the high-pressure phase. The preliminary analysis of the post mortem sample (i.e., recovered material after shock compression) indicate that there is evidence of pressure-induced amorphization of SiO₂, with planar features that are associated with fracturing. This new approach in mapping the path of quartz through all stages of shock compression to peak pressure and release to ambient conditions at time-infinity will inform how we think about impact processes on the Earth's surface and other terrestrial planets.