The effects of pressure, temperature, and iron-enrichment on shock features found within olivine gas gun shock-wave recovery experiments*

Hypervelocity impact experiments using a 30 mm, 2-stage light gas gun were performed to study the effect of increasing impact velocities on the formation of shock features found within increasingly iron-enriched olivine compositions. Separate campaigns of 6 shock recovery experiments ranging from 1.5 to 3 km/s were executed on the pure Mg olivine endmember, forsterite (Fo) (Mg₂SiO₄)- and on iron-enriched fayalitic (Fa) (Fo₈₀) compositions. This enables the study of increasing pressure (P), temperature (T), and iron content on the crystallization, formation, and evolution of recovered shock features. ALEGRA shock physics hydrocode was used to model shock wave propagation, P, T, and material conditions due to velocity and compositional changes. We utilized and expanded upon both the steel recovery assembly and experimental processes detailed in Tschauner et al. (2009). These experiments are part of a larger campaign to expand the studied compositions from the pure forsterite endmember to more Fe-enriched fayalitic compositions that are representative of what is observed in shocked meteorites. The main goal of this extended study is to constrain the high-pressure phase formation mechanisms of olivine compositions to better describe the shock history experienced by olivine-bearing meteorites.