Examining olivine and MgO using multiple compression regimes

Abstract:

Material phase relations and deformation mechanisms are tied to properties, such as viscosity and elasticity. However, the experiments used to study these quantities have very different timescales and pressure-temperature paths compared to materials within the Earth. It is therefore important to understand temperature, kinetic, and strain rate effects during the experiments used to establish phases. For high pressure shock experiments, there is limited deformation analysis completed for Earth materials. In this presentation, I will discuss high pressure deformation and phase relations in olivine and MgO across compression regimes. Our experiments utilize multiple techniques including rapid (membrane-driven) compression and shock compression. In olivine, we examine deformation at rapid compression and shock timescales. The olivine rapid compression study examines forsterite and fayalite data collected at 25 °C and compressed to 50-65 GPa. The shock study used gas guns to shock forsterite to 56 and 74 GPa. In MgO, we examine the effect of temperature path on the B1-B2 transition. We completed laser shock experiments using the OMEGA laser facility of the LLE and compare our ramp experiments to shock data collected along the Hugoniot. We compare the deformation types and rate occurring during those experiments and discuss the implications for material response.