Olivine-darkening and shock records of Martian meteorites

Abstract

Most Martian meteorites underwent severe shock metamorphism and contain dark olivine. Though the olivine darkening appears related to the presence of iron nano-particles in olivine, their detailed formation conditions and processes are not well understood. Since dark olivine is exclusively found in Martian meteorites, they may have characteristic information about the Martian shock events. To constrain its formation conditions, we compare 5 Martian and 1 chondritic meteorites. Our observations revealed that high-pressure minerals are rarely found in meteorites with dark olivine, suggesting that post shock heating prevented preservation of high-pressure minerals. More detail discussions will be presented at the meeting.