High pressure magnetic transition in pyrrhotite and impact demagnetization on Mars

P. Rochette, G. Fillion, R. Ballou, F. Brunet, B. Ouladdiaf, L. Hood

Research output: Contribution to journalArticlepeer-review

71 Scopus citations

Abstract

Using neutron diffraction under pressure at room temperature, we observed that pyrrhotite undergoes a ferrimagnetic to paramagnetic transition at about 2.8 GPa. Complete demagnetization of remanence at the same pressure is confirmed in an independent experiment. Such a proces provides a quantitative explanation of the magnetic structure of the Martian Southern Hemisphere assuming that pyrrhotite is the major magnetic mineral and that our static experiments can be extrapolated to dynamic pressure conditions. Indeed, the 3 GPa isobaric line during the two large impacts of Argyre and Hellas separates the magnetized and unmagnetized zones. We also infer a reinterpretation of Martian meteorites paleomagnetic signal.

Original languageEnglish (US)
Pages (from-to)16-1 - 16-4
JournalGeophysical Research Letters
Volume30
Issue number13
DOIs
StatePublished - Jul 1 2003
Externally publishedYes

ASJC Scopus subject areas

  • Geophysics
  • Earth and Planetary Sciences(all)

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