Journal ArticleDOI
Theory of the magnetic susceptibility of stressed rock
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TLDR
In this paper, the authors calculated the stress dependence of magnetic susceptibility of igneous rock from the multidomain theory of magnetic grains, assuming that the magnetic mineral is pure magnetite whose saturation magnetization, magnetocrystalline anisotropy and saturation magnetostriction are known.Abstract:
The stress-dependence of magnetic susceptibility of igneous rock is calculated from the multidomain theory of magnetic grains, assuming that the magnetic mineral is pure magnetite whose saturation magnetization, magnetocrystalline anisotropy and saturation magnetostriction are known. The susceptibility χ measured in the direction of a linear compression σ is given by d(ln χ)/dσ = −1.0y × 10−4 cm2/kg, in excellent agreement with measurements on a number of rocks by S. P. Kapitsa who obtained values between −0.8 × 10−4 and −1.3 × 10−4 cm2/kg. The stress-dependence of susceptibility is sufficient to cause readily observable local geomagnetic disturbances during earthquakes.read more
Citations
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Journal ArticleDOI
Magnetic anisotropy in rocks
TL;DR: In any rock six kinds of magnetic anisotropy can be distinguished, viz. shape alignment of grains, alignment of magnetic domains, stringing-together of magnetic grains, which is a special case of (1), (5) stress-induced anisotropic, and (6) exchange anisiotropy.
Journal ArticleDOI
Magnetic properties of dispersed magnetite powders
TL;DR: In this article, measurements have been made of coercive force, susceptibility, isothermal remanence, thermoremanence and thermal and alternating field demagnetization of annealed magnetite powders in nine size ranges from 1·5 μ to 120 μ.
Journal ArticleDOI
The seismomagnetic effect
TL;DR: In this article, the authors calculate local variations in the geomagnetic field, which are produced by stress changes in crustal rocks, from the stress patterns and the piezomagnetic properties of the rocks down to the Curie point isotherm.
Journal ArticleDOI
Magnetic Fabric and Its Significance in the 1400 Ma Mealy Diabase Dykes of Labrador, Canada
TL;DR: An anistropy of magnetic susceptibility (AMS) study of the relatively fresh Mealy diabase dyke swarm indicates a correlation between the AMS and the deformational effects in the rocks as discussed by the authors.
Journal ArticleDOI
Theory of the piezomagnetic effect in titanomagnetite-bearing rocks
TL;DR: In this article, the stress sensitivities of titanomagnetite-bearing rocks are calculated in terms of magnetostriction constantsλ100 andλ111 and anisotropy constantsK1,K2 of the magnetic minerals.
References
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Journal ArticleDOI
Magnetic anisotropy of igneous rocks
TL;DR: In this paper, a torque-meter method of measuring the magnetic anisotropy of rocks has been used in a study of a 1050-foot bore core from a Tasmanian dolerite sill.
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Magnetic anisotropy and fabric of some foliated rocks from S.E. Australia
TL;DR: The magnetic anisotropy of foliated rocks of several types has been measured by the torque-meter method, and shows that the alignment of long axes of magnetic grains in rocks normally follows the pattern of foliation evident in field observations as mentioned in this paper.
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Thermo-remanent magnetization (TRM) of multidomain grains in igneous rocks
TL;DR: The magnetic moment of a multidomain grain at its blocking temperature is determined by the domain arrangement which gives the minimum magnetic energy; for a large grain the energy minimum is produced by a self-demagnetizing field equal and opposite to the external field below the blocking temperature the domain configuration is frozen in and the moment increases with the increasing spontaneous magnetization as mentioned in this paper.
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Stress‐induced magnetizations of some rocks with analyzed magnetic minerals
TL;DR: In this article, the influence of axial compression on the natural magnetizations of a variety of rock core samples whose magnetic minerals have been analyzed was analyzed. And the results were offered as support of the opinion that many conclusions that have been offered on the basis of rock-magnetism data, relating to polar wandering, continental drift, secular variation, and reversal of the earth's magnetic field, are subject to serious doubt.
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Theory of the magnetic properties of igneous rocks in alternating fields
TL;DR: In this article, the authors calculated the domain size distributions for spherical and cubical grains and derived characteristic curves of the fraction of an initial thermoremanent magnetization which remains after demagnetization in a progressively increasing field.