Mineral magnetism of dusty olivine : A credible recorder of pre-accretionary remanence

Publication: Research - peer-reviewJournal article – Annual report year: 2011

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The magnetic properties of olivine-hosted Fe-Ni particles have been studied to assess the potential of "dusty olivine" to retain a pre-accretionary remanence in chondritic meteorites. Both body-centered (bcc) and face-centered cubic (fcc) Fe-Ni phases were formed by reduction of a terrestrial olivine precursor. The presence of Ni complicates the magnetic properties during heating and cooling due to the fcc-bcc martensitic transition. First-order reversal curve (FORC) diagrams contain a central ridge with a broad coercivity distribution extending to 600 mT, attributed to non-interacting single-domain (SD) particles, and a "butterfly" structure extending to 250 mT, attributed to single-vortex (SV) states. SD and SV states were imaged directly using electron holography. The location of the SD/SV boundary is broadly consistent with theoretical predictions. A method to measure the volume of individual SD particles using electron holography is presented. Combining the volume information with constraints on coercivity, we calculate the thermal relaxation characteristics of the particles and demonstrate that the high-coercivity component of remanance would remain stable for 4.6 Ga, even at temperatures approaching the Curie temperature of pure Fe. The high coercivity of the particles, together with the chemical protection offered by the surrounding olivine, is likely to make them resistant to shock remagnetization, isothermal remagnetization and terrestrial weathering, making dusty olivine a credible recorder of pre-accretionary magnetic fields. Copyright 2011 by the American Geophysical Union.
Original languageEnglish
JournalG3: Geochemistry, Geophysics, Geosystems
Publication date2011
Volume12
Journal number12
PagesQ12Z35
ISSN1525-2027
DOIs
StatePublished

Bibliographical note

Copyright 2011 American Geophysical Union

CitationsWeb of Science® Times Cited: 3

Keywords

  • Dusty olivine, Magnetic properties, Electron holography, Transmission electron microscopy, Chondrules, First-order reversal curves
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