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Studia Geophysica et Geodaetica

, Volume 50, Issue 2, pp 283–299 | Cite as

Low-field variation of magnetic susceptibility measured by the KLY-4S Kappabridge and KLF-4A magnetic susceptibility meter: Accuracy and interpretational programme

  • F. Hrouda
  • M. Chlupáčová
  • J. Pokorný
Article

Abstract

The KLY-4S Kappabridge and KLF-4A Magnetic Susceptibility Meter enable automated measurement of susceptibility variation with field in the ranges of 2–450 A/m and 5–300 A/m (in effective values), respectively. Unfortunately, the measurement accuracy decreases with decreasing field and it is not easy to decide whether the susceptibility variation at the lowest fields is natural phenomenon or results from measuring errors. To overcome this problem, the accuracies of both the above instruments were investigated experimentally using artificial specimens (mixture of pure magnetite and plaster of Paris) with variable susceptibilities ranging from 1 × 10−5 to 5 × 10−2. The complete curve of the field variation of susceptibility of each specimen was measured 10 times and the relative error was calculated for each field.

In the KLY-4S Kappabridge, in specimens with susceptibilities higher than 100 × 10−6, the relative errors are lower than 3% in all fields and lower than 1% in the fields stronger than 10 A/m. In the KLF-4A Magnetic Susceptibility Meter, in relatively strongly magnetic specimens with susceptibilities 5 × 10−4 to 5 × 10−2, the relative error is less than 1.5% in the entire field range. While the former instrument is convenient for investigating almost all rock types, the latter instrument is convenient for measuring moderately and strongly magnetic specimens.

To facilitate work with field variation of susceptibility curves, showing variable accuracies with field, the programme FieldVar was written. One of its options is plotting the measured data with corresponding field-variable error bars. In this way, a tool is offered for interpreting such susceptibility changes that are sound and reasonable from the point of view of measuring accuracy.

Key words

field-variation susceptibility magnetic mineralogy 

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References

  1. Chlupáčová M., 1984. Anisotropy of magnetic susceptibility. In: M. Chlupáčová, P. Pruner, M. Krsová, F. Hrouda and V. Jelínek (Eds.), Magnetic Properties of Rocks and Ores with Pyrrhotite. Geofyzika, Brno, Czech Republic, 76–106 (in Czech).Google Scholar
  2. de Wall H., 2000. The field dependence of AC susceptibility in titanomagnetites: implications for the anisotropy of magnetic susceptibility. Geophys. Res. Lett., 27, 2409–2411.CrossRefGoogle Scholar
  3. de Wall H. and Nano L., 2004. The use of field dependence of magnetic susceptibility for monitoring variations in titanomagnetite composition — a case study of basanites of Vogelsberg 1996 Drillhole, Germany. Stud. Geophys. Geod., 48, 767–776.CrossRefGoogle Scholar
  4. Hrouda F. 2002. Low-field variation of magnetic susceptibility and its effect on the anisotropy of magnetic susceptibility of rocks. Geophys. J. Int., 150, 715–723.CrossRefGoogle Scholar
  5. Hrouda F., Chlupáčová M. and Novák J.K., 2002. Variations in magnetic anisotropy and opaque mineralogy along a kilometer deep profile within a vertical dyke of the syenogranite porphyry at Cínovec (Czech Republic). J. Volcanol. Geotherm. Res., 113, 37–47.CrossRefGoogle Scholar
  6. Hrouda F., Chlupáčová M. and Mrázová Š., 2006. Low-field variation of magnetic susceptibility as a tool for magnetic mineralogy of rocks. Phys. Earth Planet. Inter., in print.Google Scholar
  7. Jackson M., Moskowitz B., Rosenbaum J. and Kissel C., 1998. Field-dependence of AC susceptibility in titanomagnetites. Earth Planet. Sci. Lett., 157, 129–139.CrossRefGoogle Scholar
  8. Jelínek V., 1977. The Statistical Theory of Measuring Anistropy of Magnetic Susceptibility of Rocks and its Application. Geofyzika, Brno, Czech Republic.Google Scholar
  9. Jelínek V. and Pokorný J., 1997. Some new concepts in technology of transformer bridges for measuring susceptibility anisotropy of rocks. Phys. Chem. Earth, 22, 179–181.CrossRefGoogle Scholar
  10. Markert H. and Lehmann A., 1996. Three-dimensional Rayleigh hysteresis of oriented core samples from the German Continental Deep Drilling Program: susceptibility tensor, Rayleigh tensor, three-dimensional Rayleigh law. Geophys. J. Int., 127, 201–214.Google Scholar
  11. Nagata T., 1961. Rock Magnetism. Maruzen, Tokyo, Japan.Google Scholar
  12. Pokorný J., Suza P. and Hrouda F., 2004. Anisotropy of magnetic susceptibility of rocks measured in variable weak magnetic fields using the KLY-4S Kappabridge. In: F. Martín-Hernández, C.M. Lüneburg, C. Aubourg and M. Jackson (Eds), Magnetic Fabric: Methods and Applications. Geological Society, London, Special Publications, 238, 69–76.Google Scholar
  13. Worm H.-U., 1991. Multidomain susceptibility and anomalously strong low field dependence of induced magnetization in pyrrhotite. Phys. Earth Planet. Inter., 69, 112–118.CrossRefGoogle Scholar
  14. Worm H.-U., Clark D. and Dekkers M.J., 1993. Magnetic susceptibility of pyrrhotite: grain size, field and frequency dependence. Geophys. J. Int., 114, 127–137.Google Scholar
  15. Zapletal K., 1991. Self-reversal of isothermal remanent magnetization in a pyrrhotite (Fe7S8) crystal. Phys. Earth Planet. Inter., 70, 302–311.CrossRefGoogle Scholar

Copyright information

© StudiaGeo s.r.o. 2006

Authors and Affiliations

  • F. Hrouda
    • 1
    • 2
  • M. Chlupáčová
    • 3
  • J. Pokorný
    • 1
  1. 1.AGICO Ltd.BrnoCzech Republic
  2. 2.Institute of Petrology and Structural GeologyCharles UniversityPrague 2Czech Republic
  3. 3.Prague 4Czech Republic

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