title: High-pressure minerals in eucrite suggest a small source crater on Vesta.
abstract: High-pressure minerals in meteorites are important records of shock events that have affected the surfaces of planets and asteroids. A widespread distribution of impact craters has been observed on the Vestan surface. However, very few high-pressure minerals have been discovered in Howardite-Eucrite-Diogenite (HED) meteorites. Here we present the first evidence of tissintite, vacancy-rich clinopyroxene, and super-silicic garnet in the eucrite Northwest Africa (NWA) 8003. Combined with coesite and stishovite, the presence of these high-pressure minerals and their chemical compositions reveal that solidification of melt veins in NWA 8003 began at a pressure of >~10 GPa and ceased when the pressure dropped to <~8.5 GPa. The shock temperature in the melt veins exceeded 1900 °C. Simulation results show that shock events that create impact craters of ~3 km in diameter (subject to a factor of 2 uncertainty) are associated with sufficiently high pressures to account for the occurrence of the high-pressure minerals observed in NWA 8003. This indicates that HED meteorites containing similar high-pressure minerals should be observed more frequently than previously thought.
authors.affiliation: State Key Laboratory for Mineral Deposits Research, School of Earth Sciences and Engineering, Nanjing University, Nanjing 210046, China.
authors.forename: Run-Lian
authors.initials: RL
authors.lastname: Pang
authors.affiliation: State Key Laboratory for Mineral Deposits Research, School of Earth Sciences and Engineering, Nanjing University, Nanjing 210046, China.
authors.forename: Ai-Cheng
authors.initials: AC
authors.lastname: Zhang
authors.affiliation: State Key Laboratory for Mineral Deposits Research, School of Earth Sciences and Engineering, Nanjing University, Nanjing 210046, China.
authors.forename: Shu-Zhou
authors.initials: SZ
authors.lastname: Wang
authors.affiliation: State Key Laboratory for Mineral Deposits Research, School of Earth Sciences and Engineering, Nanjing University, Nanjing 210046, China.
authors.forename: Ru-Cheng
authors.initials: RC
authors.lastname: Wang
authors.affiliation: Department of Natural History Sciences, Hokkaido University, Sapporo 060-0810, Japan.
authors.forename: Hisayoshi
authors.initials: H
authors.lastname: Yurimoto