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

Sophie Charlotte L.L. Lappe, Nathan S. Church, Takeshi Kasama, Alice Bastos Da Silva Fanta, Geoff Bromiley, Rafal E. Dunin-Borkowski, Joshua M. Feinberg, Sara Russell, Richard J. Harrison

Research output: Contribution to journalArticle

27 Scopus citations

Abstract

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.

Original languageEnglish (US)
Article numberQ12Z35
JournalGeochemistry, Geophysics, Geosystems
Volume12
Issue number12
DOIs
StatePublished - Dec 1 2011

Keywords

  • chondrules
  • dusty olivine
  • electron holography
  • first-order reversal curves
  • magnetic properties
  • transmission electron microscopy

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    Lappe, S. C. L. L., Church, N. S., Kasama, T., Da Silva Fanta, A. B., Bromiley, G., Dunin-Borkowski, R. E., Feinberg, J. M., Russell, S., & Harrison, R. J. (2011). Mineral magnetism of dusty olivine: A credible recorder of pre-accretionary remanence. Geochemistry, Geophysics, Geosystems, 12(12), [Q12Z35]. https://doi.org/10.1029/2011GC003811