High-pressure minerals in eucrite suggest a small source crater on Vesta

• Published in: Scientific reports Vol. 6; no. 1; p. 26063
• Main Authors: Pang, Run-Lian, Zhang, Ai-Cheng, Wang, Shu-Zhou, Wang, Ru-Cheng, Yurimoto, Hisayoshi
• Format: Journal Article
• Language: English
• Published: London Nature Publishing Group UK 16.05.2016; Nature Publishing Group
• Subjects: 704/445/330; 704/445/849; Humanities and Social Sciences; multidisciplinary; Science
• ISSN: 2045-2322; 2045-2322
• DOI: 10.1038/srep26063

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.