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Studia Geophysica et Geodaetica

, Volume 54, Issue 1, pp 95–120 | Cite as

Magnetomineralogy of the cordierite gneiss from the magnetic anomaly at Humpolec, Bohemian Moldanubicum (Czech Republic)

  • Václav Procházka
  • Marta Chlupáčová
  • Daniel Nižňanský
  • František Hrouda
  • Pavel Uher
  • Petr Rajlich
Article
  • 97 Downloads

Abstract

Magnetic properties as well as the magnetomineralogy were investigated in rocks underlying a 7 km long aeromagnetic anomaly situated in the Moldanubian crystalline unit of the Bohemian Massif. The anomaly is caused by highly magnetic cordierite gneiss forming a stripe of NE — SW direction east of the town of Humpolec, eastern Bohemia. Magnetic susceptibility and its anisotropy (AMS), natural remanent magnetization, field and temperature variations of susceptibility were measured. Optical study of thin sections, electron microprobe and Mössbauer studies were also used to reveal the carrier of the high susceptibility and the high NRM. There appear to be two major generations of Fe-Ti oxides: older hematite with ilmenite exsolutions (Ti-hematite) which is the dominant remanence phase, and younger magnetite, the dominant susceptibility phase, usually associated with rutile. This indicates a reaction Hematite + Ilmenite → Magnetite + + Rutile; the trace elements in magnetite, as well as texture and morphology of the oxide grains support this assertion. An additional minor portion of maghemite is revealed by Mössbauer and thermomagnetic results. The Ti-hematite belongs to the oldest mineral assemblage in the rock, despite its anhedral morphology. Inclusions in Ti-hematite, among which corundum and abundant paragonite occur, record a strongly peraluminous and probably disequilibrium association during the crystallization of the Ti-hematite.

Keywords

aeromagnetic anomaly cordierite gneiss magnetic properties thermomagnetic analysis Ti-hematite ilmenite exsolutions magnetite maghemite rutile 

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References

  1. Balsley J.R. and Buddington A.F., 1958. Iron titanium oxide minerals, rocks, and aeromagnetic anomalies of the Adirondack area, New York. Econ. Geol., 53, 777–805.CrossRefGoogle Scholar
  2. Breiter K. and Sulovský P., 2005. Geochronology of the Melechov granite massif. Zpr. Geol. Výzk. v Roce 2004, 16–19.Google Scholar
  3. Burton B.P., 1984. Thermodynamic analysis of the system Fe2O3-FeTiO3. Phys. Chem. Miner., 11, 132–139.CrossRefGoogle Scholar
  4. Burton B.P., Robinson P., McEnroe S.A., Fabian K. and Boffa Ballaran T., 2008. A Low-Temperature Phase Diagram for Ilmenite-rich Compositions in the System Fe2O3-FeTiO3. Am. Miner., 93, 1260–1272.CrossRefGoogle Scholar
  5. Carmichael C.M., 1964. Magnetization of a rock containing magnetite and hemoilmenite. Geophysics, 29, 87–92.CrossRefGoogle Scholar
  6. Čadková Z., Jakeš P., Haková M. and Mrázek P., 1985. The catalogue of geochemical data of the basic regional network. In: Litogeochemical Database of the Czech Geological Survey, Archive CGS, Prague, Czech Republic (in Czech).Google Scholar
  7. Cháb J., Stráník Z. and Eliáš M., 2007. Geological Map of the Czech Republic 1: 500 000. Czech Geological Survey, Prague, Czech Republic.Google Scholar
  8. De Wall H., 2004. The field dependence of AC susceptibility in titanomagnetites: implications for the anisotropy of magnetic susceptibility. Geophys. Res. Lett., 27, 2409–2411.CrossRefGoogle Scholar
  9. Dunlop D.J. and Özdemir Ö., 1997. Rock Magnetism: Fundamentals and Frontiers. Cambridge University Press, Cambridge, U.K.Google Scholar
  10. Fediuk F., 1974. Cordieritregelung in moldanubischen Gneissen. Krystalinikum, 10, 79–88 (in German).Google Scholar
  11. Haggerty S.E., 1991. Oxide textures — a mini-atlas. Rev. Mineral., 25, 129–219.Google Scholar
  12. Hargraves R.N., 1959. Magnetic anisotropy and remanent magnetization in hemo-ilmenite from ore deposits of Allard Lake Quebec. J. Geophys. Res., 64, 1565–1573.CrossRefGoogle Scholar
  13. Harrison R.J., 2006. Microstructure and magnetism in the ilmenite-hematite solid solutions: a Monte Carlo simulation study. Am. Miner., 91, 1006–1023.CrossRefGoogle Scholar
  14. Hrouda F., 1994. A technique for the measurement of thermal changes of magnetic susceptibility of weakly magnetic rocks by the CS-2 apparatus and KLY-2 Kappabridge. Geophys. J. Int., 118, 604–612.CrossRefGoogle Scholar
  15. 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
  16. Hrouda F., Chlupáčová M. and Pokorný J., 2006a. Low-field variation of magnetic susceptibility measured by the KLY-4S Kappabridge and KLF-4A magnetic susceptibility meter: accuracy and interpretational programme. Stud. Geophys. Geod., 50, 283–298.CrossRefGoogle Scholar
  17. Hrouda F., Chlupáčová M. and Mrázová Š., 2006b. Low-field variation of magnetic susceptibility as a tool for magnetic mineralogy of rocks. Phys. Earth Planet. Inter., 154, 323–336.CrossRefGoogle Scholar
  18. Jelínek V., 1981. Characterization of the magnetic fabrics of rocks. Tectonophysics, 79, T63–T67.CrossRefGoogle Scholar
  19. Krupička J., 1968. The contact zone in the north of the Moldanubian Pluton. Krystalinikum, 6, 7–39.Google Scholar
  20. Lindh A., 1972. A hydrothermal investigation of the system FeO, Fe2O3, TiO2. Lithos, 5, 325–343.CrossRefGoogle Scholar
  21. Lindsley D.H. and Lindh A., 1974. A hydrothermal investigation of the system FeO, Fe2O3, TiO2: a discussion with new data. Lithos, 7, 65–68.CrossRefGoogle Scholar
  22. Losert J., 1968. On the genesis of nodular sillimanitic rocks. In: Malkovský M. (Ed.), International Geological Congress. Report of the 23rd Session. Vol. 4, Proceedings of Section 4. Geology of Pre-Cambrian. Academia and Geological survey of Czechoslovakia, Praha, Czechoslovakia, 109–122.Google Scholar
  23. McEnroe S.A. and Brown L.L., 2000. A closer look at remanence-dominated aeromagnetic anomalies: Rock magnetic properties and magnetic mineralogy of the Russel Belt microcline-sillimanite gneiss, northwest Adirondack Mountain, New York. J. Geophys. Res., 105(B7), 16437–16456.CrossRefGoogle Scholar
  24. McEnroe S.A., Robinson P. and Panish P.T., 2001a. Aeromagnetic anomalies, magnetic petrology and characterization of ilmenite and magnetite cumulates of the Sokndal Region, Rogaland, Norway. Am. Miner., 86, 1147–1468.Google Scholar
  25. McEnroe S.A., Harrison R.J., Robinson P., Golla U. and Jercinovic M.J., 2001b. Effect of fine scale microstructures in titanohematite on the acquisition and stability of natural remanent magnetization in granulite facies metamorphic rocks, southern Sweden: Implication for crustal magnetism. J. Geophys. Res., 106(B12), 30532–30546.CrossRefGoogle Scholar
  26. McEnroe S.A., Robinson P., Langenhorst F., Frandsen C., Terry M.P. and Ballarn T.B., 2007. Magnetization of exsolution intergrowths of hematite and ilmenite: Mineral chemistry, phase relations, and magnetic properties of hemo-ilmenite ores with micron- to nanometer-scale lamellae from Allard Lake, Quebec. J. Gephys. Res., 112, B10103, doi: 10.1029/2007JB004973CrossRefGoogle Scholar
  27. Mücke A., 2003. Magnetite, ilmenite and ulvite in rocks and ore deposits: petrography, microprobe analyses and genetic implications. Mineral. Petrol., 77, 215–234.CrossRefGoogle Scholar
  28. Nagata T., 1961. Rock Magnetism. Maruzen, Tokyo, Japan, 352 pp.Google Scholar
  29. Özdemir Ö., Dunlop D.J. and Moskowitz B.M., 1993. The effect of oxidation on the Verwey transition in magnetite. Geophys. Res. Lett., 20, 1671–1674.CrossRefGoogle Scholar
  30. Özdemir Ö., Dunlop D.J. and Berquo T.S., 2008. Morin transition in hematite: Size dependence and thermal hysteresis. Geochem. Geophys. Geosyst., 9, Q10Z01, doi: 10.1029/2008GC002110.CrossRefGoogle Scholar
  31. Procházka V., 2007. Cordierite gneisses very rich in Ti-hematite from Orlík at Humpolec. Zprávy Geol. Výzk. v roce 2006, 133–135 (in Czech).Google Scholar
  32. Procházka V., Matějka D. and Uher P., 2008. New information from known as well as unknown rocks in the surroundings of Lipnice nad Sázavou. Zpr. Geol. Výzk. v roce 2007, 30–33 (in Czech).Google Scholar
  33. Řeháčková M., Šalanský K. and Zemánek V., 1963. Report about the Airborne Geophysical Measurement in 1961, III., Pelhřimov Surroundings. MS Geofond ČR, Prague, Czech Republic (in Czech).Google Scholar
  34. Robinson P., Harrison R.J., McEnroe S.A. and Hargraves R.B., 2002. Lamellar magnetism in the hematite-ilmenite series as an explanation for strong remanent magnetization. Nature, 418, 517–520.CrossRefGoogle Scholar
  35. Robinson P., Harrison R.J., McEnroe S.A. and Hargraves R.B., 2004. Nature and origin of lamellar magnetism in the hematite-ilmenite series. Am. Miner., 89, 725–747.Google Scholar
  36. Robinson P., Heidelbach F., Hirt A.M., McEnroe S.A. and Brown L.L., 2006. Crystallographic-magnetic correlations in single-crystal haemo-ilmenite: new evidence for lamellar magnetism. Geophys. J. Int., 165, 17–31.CrossRefGoogle Scholar
  37. Scharbert S. and Veselá M., 1990. Rb-Sr systematics of intrusive rocks from the Moldanubicum around Jihlava. In: Minaříková D. and Lobitzer H. (Eds.), 30 Years of Geological Cooperation between Austria and Czechoslovakia. Czech Geological Survey, Prague, Czech Republic, 262–271.Google Scholar
  38. Suk M., 1964. Material characteristics of the metamorphism and migmatization of Moldanubian paragneisses in central Bohemia. Krystalinikum, 2, 71–105.Google Scholar
  39. Šalanský K., 1983. Regional magnetic structures in the Bohemian Massif on the territory of Czechoslovakia. Věst. Ústř. Úst. geol., 58, 275–286 (in Czech).Google Scholar
  40. Štěpánek P. (Ed.), 1995. Geological Map of the Czech Republic 1: 50 000, Sheet 23-21 Havlíčkův Brod. Czech Geological Survey, Prague, Czech Republic.Google Scholar
  41. Štěpánek P., 2002. Explanations to the Basic Geological Map of the Czech Republic 1: 25 000, Sheet 23-213 Humpolec. Czech Geological Survey, Prague, Czech Republic (in Czech).Google Scholar
  42. Tarling D.H. and Hrouda F., 1993. The Magnetic Anisotropy of Rocks. Chapman & Hall, London, 217 pp.Google Scholar
  43. 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.CrossRefGoogle Scholar
  44. Zemánek V., 1964. Interpretation of Magnetic Anomalies in the Chýnov and Humpolec Regions. PhD Thesis, Faculty of Science of the Charles University, Prague, Czech Republic (in Czech).Google Scholar
  45. Zemánek V., 1967. Interpretation of magnetic anomalies in the Obrataň and Humpolec regions of the Moladanubian. Sbor. Geol. Věd, Užitá Geofyz., 6, 125–153.Google Scholar

Copyright information

© Institute of Geophysics of the ASCR, v.v.i 2010

Authors and Affiliations

  • Václav Procházka
    • 1
    • 2
  • Marta Chlupáčová
    • 3
  • Daniel Nižňanský
    • 4
  • František Hrouda
    • 5
  • Pavel Uher
    • 6
  • Petr Rajlich
    • 7
  1. 1.Institute of Geochemistry, Mineralogy and Mineral ResourcesFaculty of Science of the Charles UniversityPraha 2Czech Republic
  2. 2.Institute of Chemical TechologyPraha 6Czech Republic
  3. 3.Praha 4Czech Republic
  4. 4.Department of Inorganic ChemistryFaculty of Science of the Charles UniversityPraha 2Czech Republic
  5. 5.Institute of Petrology and Structural GeologyFaculty of Science of the Charles UniversityPraha 2Czech Republic
  6. 6.Department of Geology of Mineral DepositsFaculty of Science of the Comenius UniversityBratislavaSlovakia
  7. 7.South-Bohemian MuseumČeské BudějoviceCzech Republic

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