科研之友
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摘要
From mid-Ordovician similar to 470 Myr-old limestone > 100 fossil L-chondritic meteorites have been recovered, representing the markedly enhanced flux of meteorites to Earth following the breakup of the L-chondrite parent body. Recently one anomalous meteorite, Osterplana 065 (Ost 65), was found in the same beds that yield L chondrites. The cosmic-ray exposure age of Ost 65 shows that it may be a fragment of the impactor that broke up the L-chondrite parent body. Here we show that in a chromium versus oxygen-isotope plot O Ost 65 falls outside all fields encompassing the known meteorite types. This may be the first documented example of an `extinct' meteorite, that is, a meteorite type that does not fall on Earth today because its parent body has been consumed by collisions. The meteorites found on Earth today apparently do not give a full representation of the kind of bodies in the asteroid belt similar to 500 Myr ago.
- 出版日期2016-6
