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Thermoremanence acquisition and demagnetization for titanomagnetite under lithospheric pressures
Author(s) -
Launay Nicolas,
Rochette Pierre,
Quesnel Yoann,
Demory François,
Bezaeva Natalia S.,
Lattard Dominique
Publication year - 2017
Publication title -
geophysical research letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.007
H-Index - 273
eISSN - 1944-8007
pISSN - 0094-8276
DOI - 10.1002/2017gl073279
Subject(s) - geology , demagnetizing field , lithosphere , hydrostatic equilibrium , curie temperature , magnetometer , hydrostatic pressure , geophysics , thermal , magnetic anomaly , magnetization , petrology , mineralogy , magnetic field , condensed matter physics , seismology , thermodynamics , tectonics , physics , quantum mechanics , ferromagnetism
The geological sources of large‐scale lithospheric magnetic field anomalies are poorly constrained. Understanding the magnetic behavior of rocks and minerals under the pressures and temperatures encountered at large crustal depths is particularly important in that task. The impact of lithospheric pressure is not well known and most of the time neglected in numerical models of the geological sources of magnetic anomalies. We present thermal remanent magnetization (TRM) acquisition and stepwise thermal demagnetization on synthetic titanomagnetite dispersed powder, within an amagnetic cell under hydrostatic pressure up to 1 GPa. TRM is measured after thermal cycling within a cryogenic magnetometer. Pressure‐dependent increase in the Curie temperature (initially in the 50–70°C range) is observed, mostly between 0.3 and 0.6 GPa, on the order of 20 K/GPa. TRM intensity also increases with pressure up to 200% at 675 MPa, although the pressure variation with temperature inside the cell complicates the interpretation.