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A Time-Resolved Paleomagnetic Record of Main Group Pallasites: Evidence for a Large-Cored, Thin-Mantled Parent Body

Published version
Peer-reviewed

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Article

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Abstract

jats:titleAbstract</jats:title>jats:pSeveral paleomagnetic studies have been conducted on five Main Group pallasites: Brenham, Marjalahti, Springwater, Imilac, and Esquel. These pallasites have distinct cooling histories, meaning that their paleomagnetic records may have been acquired at different times during the thermal evolution of their parent body. Here, we compile new and existing data to present the most complete time‐resolved paleomagnetic record for a planetesimal, which includes a period of quiescence prior to core solidification as well as dynamo activity generated by compositional convection during core solidification. We present new paleomagnetic data for the Springwater pallasite, which constrains the timing of core solidification. Our results suggest that in order to generate the observed strong paleointensities (∼65–95 μT), the pallasites must have been relatively close to the dynamo source. Our thermal and dynamo models predict that the Main Group pallasites originate from a planetesimal with a large core (>200 km) and a thin mantle (<70 km).</jats:p>

Description

Funder: FP7 Ideas: European Research Council (FP7 Ideas); Id: http://dx.doi.org/10.13039/100011199; Grant(s): 320750, 312284


Funder: NASA Solar Systems Workings program


Funder: The Geological Society


Funder: Mineralogical Society of Great Britain


Funder: Mineral Physics Group of Great Britain


Funder: Jesus College Cambridge


Funder: Royal Astronomical Society; Id: http://dx.doi.org/10.13039/501100000698

Keywords

paleomagnetism, pallasite meteorites, paleointensity, core dynamo, planetesimal

Journal Title

Journal of Geophysical Research: Planets

Conference Name

Journal ISSN

2169-9097
2169-9100

Volume Title

126

Publisher

American Geophysical Union (AGU)
Sponsorship
European Research Council (320750)