THE EFFECT OF HYDROSTATIC PRESSURE UP TO 1.45 GPA ON THE MORIN TRANSITION OF HEMATITE-BEARING ROCK: IMPLICATIONS FOR PLANETARY CRUSTAL MAGNETIZATION
Résumé
We present new experimental data on the dependence of the Morin transition temperature (TM) on hydrostatic pressure up to 1.61 GPa, obtained on a well-characterized multidomain hematite-bearing sample from a banded iron formation. We used a nonmagnetic high-pressure cell for pressure application
and a Superconducting Quantum Interference Device magnetometer to measure the isothermal remanent magnetization (IRM) under pressure on warming from 243 K to room temperature (T0). IRM imparted at T0 under pressure in 270 mT magnetic field (IRM270mT) is not recovered after a cooling-warming cycle. Memory effect under pressure was quantified as IRM recovery decrease of 10%/GPa. TM, determined on warming, reaches T0 under hydrostatic pressure 1.38–1.61 GPa. The pressure dependence of TM up to 1.61 GPa is positive and essentially linear with a slope dTM/dP = (25 ± 2) K/GPa. This estimate is more precise than previous ones and allows quantifying the effect of a pressure wave on the upper crust magnetization, with special emphasis on Mars.
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Geophysical Research Letters - 2015 - Bezaeva - The effect of hydrostatic pressure up to 1 61 GPa on the Morin transition.pdf (527.05 Ko)
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