45億年の物質進化の記録をとどめる鉱物を求めて

概要

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By combining mineralogical studies and multi-isotopic chronological studies on samples from the earliest planetary crusts recovered from the moon, Antarctica and hot deserts, we are now in a position to propose a new concept “Evolution of Planetary Materials”. For example, a coarse-grained andesitic material rich in Na-plagioclase and diopside in the IAB iron meteorite represents a partial melt of chondritic materials with 39Ar-40Ar age of 4520 Ma. An Antarctic eucrite, Asuka 881394 possibly from a crust of 4Vesta gives 26Al-26Mg age of 4562±1 Ma relative to the age for Allende CAI. A gray anorthositic clast in lunar meteorite Y86032 formed from a magma ocean gives 39Ar-40Ar age of ∼4400 Ma. Many lunar and Martian meteorites recovered from hot deserts recently give us more chances of studying these planets. Dhofar 489 gives us information on the magnesian anorthosite and Dhofar 378 is a product of the latest volcanic activities of Mars. Within a decade, we will be able to obtain minerals beyond the Earth-Moon system by sample-return missions from asteroids, comets and Mars. Detailed mineralogical, geochemical studies of these samples and remote-sensing missions will further advance the idea of “Evolution of Planetary Materials” in the 21st century.
日本鉱物科学会の論文
2003-05-30