Evidence for a Dynamo in the Main Group Pallasite Parent Body

Understanding the origin of pallasites, stony-iron meteorites made mainly of olivine crystals and FeNi metal, has been a vexing problem since their discovery. Here, we show that pallasite olivines host minute magnetic inclusions that have favorable magnetic recording properties. Our paleointensity m...

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Bibliographic Details
Published in:Science (American Association for the Advancement of Science) 2012-11, Vol.338 (6109), p.939-942
Main Authors: Tarduno, John A., Cottrell, Rory D., Nimmo, Francis, Hopkins, Julianna, Voronov, Julia, Erickson, Austen, Blackman, Eric, Scott, Edward R.D., McKinley, Robert
Format: Article
Language:English
Subjects:
Asteroids
Boundaries
Cooling
Core mantle boundary
Cosmochemistry. Extraterrestrial geology
Crystals
Demagnetization
Earth sciences
Earth, ocean, space
Exact sciences and technology
Liquids
Magnetic fields
Magnetization
Meteorites
Meteorites. Tectites. Impactites
Meteors & meteorites
Olivine
Parents
Planets
Protoplanets
Rotating generators
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Summary:Understanding the origin of pallasites, stony-iron meteorites made mainly of olivine crystals and FeNi metal, has been a vexing problem since their discovery. Here, we show that pallasite olivines host minute magnetic inclusions that have favorable magnetic recording properties. Our paleointensity measurements indicate strong paleomagnetic fields, suggesting dynamo action in the pallasite parent body. We use these data and thermal modeling to suggest that some pallasites formed when liquid FeNi from the core of an impactor was injected as dikes into the shallow mantle of a ~200-kilometer-radius protoplanet. The protoplanet remained intact for at least several tens of millions of years after the olivine-metal mixing event.
ISSN:0036-8075
1095-9203
DOI:10.1126/science.1223932