Long-lived magnetism from solidification-driven convection on the pallasite parent body

DOI: 10.1038/nature14114
PMID: 25612050

Authors: James F. J. Bryson (University of Cambridge) , Claire I. O. Nichols (University of Cambridge) , Julia Herrero-Albillos (Centro Universitario de la Defensa) , Florian Kronast (Helmholtz-Zentrum Berlin für Materialien und Energie) , Takeshi Kasama (Technical University of Denmark) , Hossein Alimadadi (Technical University of Denmark) , Gerrit Van Der Laan (Diamond Light Source) , Francis Nimmo (University of California) , Richard J. Harrison (University of Cambridge)
Co-authored by industrial partner: No

Type: Journal Paper
Journal: Nature , VOL 517 (7535) , PAGES 472 - 475

State: Published (Approved)
Published: January 2015

Abstract: Palaeomagnetic measurements of meteorites1, 2, 3, 4, 5 suggest that, shortly after the birth of the Solar System, the molten metallic cores of many small planetary bodies convected vigorously and were capable of generating magnetic fields6. Convection on these bodies is currently thought to have been thermally driven7, 8, implying that magnetic activity would have been short-lived9. Here we report a time-series palaeomagnetic record derived from nanomagnetic imaging10 of the Imilac and Esquel pallasite meteorites, a group of meteorites consisting of centimetre-sized metallic and silicate phases. We find a history of long-lived magnetic activity on the pallasite parent body, capturing the decay and eventual shutdown of the magnetic field as core solidification completed. We demonstrate that magnetic activity driven by progressive solidification of an inner core11, 12, 13 is consistent with our measured magnetic field characteristics and cooling rates14. Solidification-driven convection was probably common among small body cores15, and, in contrast to thermally driven convection, will have led to a relatively late (hundreds of millions of years after accretion), long-lasting, intense and widespread epoch of magnetic activity among these bodies in the early Solar System.

Journal Keywords: Palaeomagnetism; Meteorites; XPEEM; XMCD; Nanomagnetism; Tetrataenite

Diamond Keywords: Meteorites

Subject Areas: Earth Science, Physics

Facility: SPEEM UE49 at BESSY II

Added On: 23/01/2015 10:29

Discipline Tags:

Earth Sciences & Environment Physics Magnetism Geology Geophysics Planetary Geology

Technical Tags: