隕石と宇宙塵の鉱物学・岩石学

抄録

Extraterrestorial materials are divided into two categories based on their sizes: meteorites are >1mm across, and cosmic dusts<1mm across. Because most of cosmic dusts experienced severe heating during atmospheric entry, they were melted or hydrous minerals in them were decomposed into the aggregates of anhydrous minerals. However, some cosmic dusts keep original mineralogy and petrology before atmospheric entry, due to lower peak temperatures during the entry. Mineralogy and petrology, as well as chemistry, of such cosmic dusts (many interplanetary dust particles (IDPs) and some micrometeorites) are different from those of meteorites. Therefore, it is clear that such cosmic dusts are different in origin from meteorites. Parent bodies of some pyroxene-class anhydrous IDPs and some smectite-class hydrated IDPs may be comets. On the other hand, parent bodies of most of IDPs and a part of undehydrated micrometeorites are probably asteroids which are different from the meteorite parent bodies.