Generation of pseudotachylites in shock experiments: Implications for impact cratering products and processes

摘要

While the role of pressure on the formation of shock metamorphic features has been well studied, the role of strain and strain rate has not been fully appreciated. We shock loaded single-crystal quartz in Al capsules up to 56 GPa using a novel capsule design that allows for significant strain of the sample but 100% recovery of material. We have made features analogous to type A pseudotachylites at pressures of 42-56 GPa. These pseudotachylites contain Al, Si, and minor Al2O3 in a matrix of SiO2 class and cut the sample along radial and concentric fractures. Our results suggest that strain heating is an important energy sink in the formation of large impact craters.