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Anisotropy of out-of-phase magnetic susceptibility of rocks as a tool for direct determination of magnetic subfabrics of some minerals: an introductory study
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SYSNO ASEP 0476861 Document Type J - Journal Article R&D Document Type Journal Article Subsidiary J Článek ve WOS Title Anisotropy of out-of-phase magnetic susceptibility of rocks as a tool for direct determination of magnetic subfabrics of some minerals: an introductory study Author(s) Hrouda, F. (CZ)
Chadima, Martin (GLU-S) RID, SAI
Ježek, J. (CZ)
Pokorný, J. (CZ)Source Title Geophysical Journal International - ISSN 0956-540X
Roč. 208, č. 1 (2017), s. 385-402Number of pages 18 s. Publication form Print - P Language eng - English Country GB - United Kingdom Keywords magnetic and electrical properties ; magnetic fabrics and anisotropy ; magnetic mineralogy and petrology ; rock and mineral magnetism Subject RIV DB - Geology ; Mineralogy OECD category Geology R&D Projects IAAX00130801 GA AV ČR - Academy of Sciences of the Czech Republic (AV ČR) Institutional support GLU-S - RVO:67985831 UT WOS 000396814800029 EID SCOPUS 85024123080 DOI 10.1093/gji/ggw399 Annotation The magnetic susceptibility measured in alternating field can in general be resolved into a component that is in-phase with the applied field and a component that is out-of-phase. While in non-conductive diamagnetic, paramagnetic and many ferromagnetic materials the phase is effectively zero, in some ferromagnetic minerals, such as pyrrhotite, hematite, titanomagnetite or small magnetically viscous grains of magnetite, it is clearly non-zero. The anisotropy of out-of-phase susceptibility (opAMS) can then be used as a tool for the direct determination of the magnetic subfabrics of the minerals with non-zero phase. The error in determination of out-of-phase susceptibility non-linearly increases with decreasing phase angle. This may result in imprecise determination of the opAMS in specimens with very low phase angle. The degree of opAMS is higher than that of ipAMS, which may in contrast result in slightly increasing precision n the opAMS determination. It is highly recommended to inspect the results of the statistical tests of each specimen and to exclude the specimens whose opAMS is determined with insufficient precision from further processing. In rocks, whose magnetism is dominated by the mineral with non-zero out-of-phase susceptibility, the principal directions of the opAMS and ipAMS are virtually coaxial, while the degree of opAMS is higher than that of ipAMS. In some specific cases, the opAMS provides us with similar data to those provided by anisotropies of low-field dependent susceptibility and frequency-dependent susceptibility. The advantage of the opAMS compared to the other two anisotropies is its simultaneous measurement with the ipAMS during one measuring process, while the other two anisotropies require the AMS measurements in several fields or at least at two operating frequencies. Workplace Institute of Geology Contact Jana Popelková, popelkova@gli.cas.cz, Sabina Janíčková, Tel.: 233 087 272 Year of Publishing 2018
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