grained, igneous rock, namely a cumulate orthopyroxenite, with a crystallization age of 4.56 Ga [Mittlefehldt, 1994]. Treiman [1995] states that ALH84001is plutonic not volcanic, unlike the other Martian meteorites. This sample records evidence of two shock metamorphic events (impacts), separated by...
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| Format: | Text |
| Language: | English |
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| Online Access: | http://citeseerx.ist.psu.edu/viewdoc/summary?doi=10.1.1.587.2958 http://www.lpi.usra.edu/meetings/lpsc97/pdf/1859.PDF |
| Summary: | grained, igneous rock, namely a cumulate orthopyroxenite, with a crystallization age of 4.56 Ga [Mittlefehldt, 1994]. Treiman [1995] states that ALH84001is plutonic not volcanic, unlike the other Martian meteorites. This sample records evidence of two shock metamorphic events (impacts), separated by thermal metamorphism and low temperature chemical alteration events [Treiman, 1995]. The first impact event shattered the basement rock where ALH84001 was located. Following the initial impact event, ALH84001 underwent alteration and endured a second shock event, possibly from the meteorite impact that eventually ejected the rock from Mars. The cosmic ray exposure age of ALH84001 is 16 Ma, this date records the meteorite's time spent in space before impacting upon Earth. ALH84001 landed in the icefields of Antarctica 13,000 years ago and was subsequently collected in 1984 at the Allan Hills, Far Western Icefield. Therefore, based on ALH84001's significant age (4.5 Ga) and history of multiple shock events (crater impacts) it seems quite reasonable to assume that the rock formed in an ancient region (Noachian Age) of the Martian surface, namely the cratered highlands. The focus of this paper is to locate candidate parent craters for the Martian meteorite ALH84001 based upon extensive photogeologic analysis of 1:2,000,000 scale |
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