Title: Static
stress demagnetization of single and multidomain magnetite with
implications for meteorite impacts
Source: HIGH
PRESSURE RESEARCH 26 (4): 539-547 DEC 2006
Document Type: Article
Language: English
Abstract: Stress
demagnetization effects on ferromagnetic minerals are poorly known,
especially above 1 GPa, and when initially magnetized under pressure
and then subjected to further stress. Our experiments on pure magnetite
under quasi-hydrostatic loads in the presence of a small (Earth's)
field show that stress demagnetization depends on domain state and
stress history. Viewed globally, the results follow a simple law where
the percentage loss in magnetic moment is the inverse of pressure
(e.g., 50% loss in moment at 1 GPa, 67% loss at 2 GPa, etc.). Our
experiments also quantify the effect of demagnetization upon stress
release, where the moment upon full decompression is two-thirds less
than the moment when decompression first began. Given the magnitude of
the stress demagnetization effect, we conclude that the presence or
absence of a planetary magnetic field cannot be deduced from the
magnetic fields measured over meteorite craters, such as those on Mars.
Author Keywords: stress;
demagnetization; magnetite; meteorite crater
KeyWords Plus: MARTIAN
CRUST; REMANENT MAGNETIZATION; UNIAXIAL COMPRESSION; SUSCEPTIBILITY;
ROCKS; MARS; SHOCK; TITANOMAGNETITES; EARTHQUAKE; PRESSURE
Addresses: Gilder
SA (reprint author), Inst Phys Globe, Equipe Paleomagnetisme, 4 Pl
Jussieu, F-75252 Paris 05, France
Inst Phys Globe, Equipe Paleomagnetisme, F-75252
Paris 05, France
Univ Munich, Dept Earth & Environm Sci, Geophys Sect, D-80333 Munich, Germany
Univ Paris 06, CNRS, UMR 7590, Dept Phys Mil Denses,Inst Mineral &
Phys Mil Cond, F-75015 Paris, France
Publisher: TAYLOR
& FRANCIS LTD, 4 PARK SQUARE, MILTON PARK, ABINGDON OX14 4RN, OXON,
ENGLAND
Subject Category: Physics,
Multidisciplinary
IDS Number: 132KX
ISSN: 0895-7959
