Title of article :
Magnetic properties of a freshly fallen LL ordinary chondrite: the Bensour meteorite
Author/Authors :
Gattacceca، نويسنده , , Jérôme and Rochette، نويسنده , , Pierre and Bourot-Denise، نويسنده , , Michèle، نويسنده ,
Issue Information :
روزنامه با شماره پیاپی سال 2003
Pages :
16
From page :
343
To page :
358
Abstract :
A comprehensive rock magnetic, magnetic anisotropy and paleomagnetic study has been undertaken in the brecciated LL6 Bensour ordinary chondrite, a few months only after its fall on Earth. Microscopic observations and electronic microprobe analyses indicate the presence of Ni-rich taenite, tetrataenite and rare Co-rich kamacite. Tetrataenite is the main carrier of remanence. Magnetization and anisotropy measurements were performed on mutually oriented 125 mm3 sub-samples. A very strong coherent susceptibility and remanence anisotropy is evidenced and interpreted as due to the large impact responsible for the post-metamorphic compaction of this brecciated material and disruption of the parent body. We show that the acquisition of remanent magnetization postdates metamorphism on the parent body and predates the entering of the meteorite in Earth’s atmosphere. Three components of magnetization could be isolated. A soft coherent component is closely related to the anisotropy of the meteorite and is interpreted as a shock remanent magnetization acquired during the same large impact on the parent body. Two harder components show random directions at a few mm scale. This randomness is attributed either to the formation mechanism of tetrataenite or to post-metamorphic brecciation. All components are likely acquired in very low (≈μT) to null ambient magnetic field, as demonstrated by comparison with demagnetization behavior of isothermal remanent magnetization. Two other LL6 meteorites, Kilabo and St-Mesmin, have also been studied for comparison with Bensour.
Keywords :
Magnetic anisotropy , ROCK MAGNETISM , Shock magnetization , Ordinary chondrite , Tetrataenite
Journal title :
PHYSICS OF THE EARTH AND PLANETARY INTERIORS
Serial Year :
2003
Journal title :
PHYSICS OF THE EARTH AND PLANETARY INTERIORS
Record number :
2306266
Link To Document :
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