Asteroidal Lava Flows--- Meteorite studies indicate that we have pieces of lava flows from at least five asteroids.
Some meteorites are pieces of lava flows. They have the expected minerals present and the crystals are intertwined in a characteristic way indicative of crystallization in a lava flow. This shows that lavas erupted on at least some asteroids. Age dating indicates that the eruptions took place 4.5 bi...
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| Language: | English |
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2003
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| Online Access: | http://citeseerx.ist.psu.edu/viewdoc/summary?doi=10.1.1.693.8928 http://www.psrd.hawaii.edu/April03/PSRD-asteroidalLava.pdf |
| Summary: | Some meteorites are pieces of lava flows. They have the expected minerals present and the crystals are intertwined in a characteristic way indicative of crystallization in a lava flow. This shows that lavas erupted on at least some asteroids. Age dating indicates that the eruptions took place 4.5 billion years ago. Planetary scientists have recognized three main groups of asteroidal lava flows, each distinctive enough to show that they must come from different asteroids. The most abundant are the eucrites, which might actually hail from asteroid 4 Vesta. Mesosiderites are complex mixtures of smashed up volcanic rock and metallic iron. Angrites have a distinctive group of minerals in them, but also clearly formed by volcanism. Recent studies increase the number of groups to five. David Mittlefehldt (Johnson Space Center) and colleagues Marvin Killgore (Southwest Meteorite Lab) and Michael Lee (Hernandez Engineering, Houston, Texas) show that the five known angrites probably represent at least two different asteroids. Four of the angrites are fairly similar to each other in chemical composition, but a fourth, Angra dos Reis, was very different and may come from an entirely different asteroid. (This is ironic as the group derives its name from Angra dos Reis.) Akira Yamaguchi (National Institute of Polar Research, Tokyo, Japan) and colleagues in Japan at the University of Chicago show that a recently found eucrite, Northwest Africa 011 (NWA 011 for short), has a quite different composition of its oxygen isotopes than the rest of the eucrites. They suggest that NWA 011 comes from a different asteroid than the other eucrites. Thus, it appears that we have samples of lava flows from five different asteroids. |
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