Japan Geoscience Union Meeting 2015

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Symbol P (Space and Planetary Sciences) » P-PS Planetary Sciences

[P-PS22] Formation and evolution of planetary materials in the solar system

Thu. May 28, 2015 4:15 PM - 6:00 PM A02 (APA HOTEL&RESORT TOKYO BAY MAKUHARI)

Convener:*Shoichi Itoh(Graduate school of Science, Kyoto University), Tomohiro Usui(Department of Earth and Planetary Sciences,Tokyo Institute of Technology), Yusuke Seto(Graduate School of Science, Kobe University), Masaaki Miyahara(Department of Earth and Planetary Systems Science, Graduate School of Science, Hiroshima University), Makoto Kimura(Faculty of Science, Ibaraki University), Eiji Ohtani(Department of Earth and Planetary Materials Science, Graduate School of Science, Tohoku University), Hitoshi Miura(Graduate School of Natural Sciences, Department of Information and Biological Sciences, Nagoya City University), Hikaru Yabuta(Osaka University, Department of Earth and Space Science), Chair:Tomohiro Usui(Department of Earth and Planetary Sciences,Tokyo Institute of Technology)

5:30 PM - 5:45 PM

[PPS22-25] Crystallization and cooling conditions for the diogenite formation in the turbulent magma ocean of the asteroid 4 Vesta

*Yusuke KAWABATA1, Hiroko NAGAHARA1 (1.Earth and Planetary Science, The University of Tokyo)

Keywords:magma ocean, Asteroid 4 Vesta, HED meteorites

The asteroid 4 Vesta has been completely differentiated to core and mantle despite its small size, of which surface materials are howardite-eucrite-diogenite (HED) meteorites that we know the detailed petrology, and therefor, is a good target for understanding differentiation of terrestrial planets. A new differentiation model for crust formation was developed by taking magma ocean fluid dynamics, chemical equilibrium, presence of 26Al, and cooling into consideration with special care to crystal separation. The role of crystal size, thickness of the conductive lib, and fO2 are evaluated as parameters. Large crystals (1cm) settle and form a km-thick cumulate layer of orthopyroxene with Mg# of 0.70-0.90 in 20 thousand years, which almost agrees with the Mg# of diogenites, whereas thinner layers are formed if the grain size is smaller.