CHLORITICKÝ HORNBLENDIT S OLIVÍNEM A SPINELEM Z LOUKOVIC U MORAVSKÝCH BUDĚJOVIC (MOLDANUBIKUM, ZÁPADNÍ MORAVA)

Roč.19,č.1-2(2012)

Abstrakt

Ultramafic rock was found in the Varied Group of Moldanubicum near Loukovice (western Moravia). It is composed predominantly by chlorite and amphibole, locally rich in ferroan spinel and serpentinised magnesian olivine (Fo = 73–81 mol. %). Their current mineral assemblage originally corresponded to pyroxenic peridotite (olivine and/or pyroxene-rich rock) metamorphosed under upper amphibolite facies conditions. Older mineral assemblage Ol + Cpx + Opx + Sp indicates the temperature 786–804 °C for pressures near 8 kbar. Amphibole (magnesiohornblende) and chlorite (clinochlore) formed during the metamorphosis at temperatures of 714 ± 34 °C and expected pressures around 8 kbar or less.


Klíčová slova:
spinel; olivine; chlorite hornblendite; P-T conditions; Varied Group; Moldanubicum
Reference

Ackerman, L. – Jelínek, E. – Medaris, G. – Ježek, J. – Siebel, W. – Strnad, L. (2009): Geochemistry of Fe-rich peridotites and associated pyroxenites from Horni Bory, Bohemian Massif: Insights into subduction-related melt-rock reactions. – Chemical Geology, 259, 15–167.

Ballhaus, C. – Berry, R. F. – Green, D. H. (1991): High pressure experimental calibration of the olivine-orthopyroxene-spinel oxygen geobarometer: implications for the oxidation state of the upper mantle. – Contributions to Mineralogy and Petrology, 107, 27–40.

Büttner, S. – Kruhl, J. H. (1997): The evolution of a late-Variscan high-T/low-P region: the southeastern margin of the Bohemian Massif. – Geologische Rundschau, 86, 21–38. DOI: http://dx.doi.org/10.1007/s005310050119">10.1007/s005310050119

Farahat, E. S. (2008): Chrome-spinels in serpentinites and talc carbonates of the El Ideid-El Sodmein District, central Eastern Desert, Egypt: their metamorphism and petrogenetic implications. – Chemie der Erde - Geochemistry, 68(2), 193–205. DOI: http://dx.doi.org/10.1016/j.chemer.2006.01.003">10.1016/j.chemer.2006.01.003

Holland, T. J. B. – Powell, R. (1998): An internally consistent thermodynamic data set for phases of petrological interest. – Journal of Metamorphic Geology, 16, 309–343. DOI: http://dx.doi.org/10.1111/j.1525-1314.1998.00140.x">10.1111/j.1525-1314.1998.00140.x

Houzar, S. (1994): Železná ruda u Loukovic – Naším krajem 4, 6, 76–77.

Houzar, S. – Novák, M. (2006): Clintonite-bearing assemblage in chondrodite marbles from the Moldanubian Zone, western Moravia, Bohemian Massif. – Journal of the Czech Geological Society, 51, 3–4, 249–258.

Jenkins, D. M. (1981): Experimental phase relations of hydrous peridotites modelled in the system H2O-CaO-MgO-Al2O3-SiO2. – Contributions to Mineralogy and Petrology, 77, 166–176.

Krmíček, L. – Cempírek, J. – Havlín, A. – Přichystal, A. – Houzar, S. – Krmíčková, M. – Gadas, P. (2011): Mineralogy and petrogenesis of a Ba-Ti-Zr-rich peralkaline dyke from Šebkovice (Czech Republic): Recognition of the most lamproitic Variscan intrusion. – Lithos, 121, 74–86. DOI: http://dx.doi.org/10.1016/j.lithos.2010.10.005">10.1016/j.lithos.2010.10.005

Leake, B. E. – Woolley, A. R. – Arps, C. E. S. – Birch, W. D. – Gilbert, M. C. – Grice, J. D. – Hawthorne, F. C. – Kato, A. – Kisch, H. J. – Krivovichev, V. G. – Linthout, K. – Laird, J. – Mandarino, J. A. – Maresch, W. V. – Nickel, E. H. – Rock, N. M. S. – Schumacher, J. C. – Smith, D. C. – Stephenson, N. C. N. – Ungaretti, L. – Whittaker, E. J. W. – Youzhi, G. (1997): Nomenclature of amphiboles: Report of the subcommittee on amphiboles of the international mineralogical association, commission on new minerals and mineral names. – American Mineralogist, 82, 1019–1037.

Machart, J. (1984): Ultramafic rocks in the Bohemian part of the Moldanubicum and central Bohemian islet zone (Bohemian Massif). – Krystalinikum, 17, 13–32.

Medaris, G. jr. – Wang, H. – Jelínek, E. – Mihaljevič, M. – Jakeš, P. (2005): Characteristics and origins of diverse Variscan peridotites in the Gföhl Nappe, Bohemian Massif, Czech Republic. – Lithos, 82, 1–23. DOI: http://dx.doi.org/10.1016/j.lithos.2004.12.004">10.1016/j.lithos.2004.12.004

Medaris, L. G. – Beard, B. L. – Jelínek, E. (2006): Mantle-Derived, UHP Garnet Pyroxenite and Eclogite in the Moldanubian Gföhl Nappe, Bohemian Massif: A Geochemical Review, New P-T Determinations, and tectonic Interpretation. – International Geology Review, 48, 765–777. DOI: http://dx.doi.org/10.2747/0020-6814.48.9.765">10.2747/0020-6814.48.9.765

Nakamura, D. – Svojtka, M. – Naemura, K. – Hirajima, T. (2004): Very high-pressure (> 4 GPa) eclogite associated with the Moldanubian Zone garnet peridotite (Nové Dvory, Czech Republic). – Journal of Metamorphic Geology, 22, 593–603. DOI: http://dx.doi.org/10.1111/j.1525-1314.2004.00536.x">10.1111/j.1525-1314.2004.00536.x

Petrakakis, K. (1986): Metamorphism of high-grade gneisses from the Moldanubian Zone, Austria, with particular reference to garnets. – Journal of Metamorphic Geology, 4, 323–344. DOI: http://dx.doi.org/10.1111/j.1525-1314.1986.tb00354.x">10.1111/j.1525-1314.1986.tb00354.x

Petrakakis, K. (1997) Evolution of Moldanubian rocks in Austria: review and synthesis. – Journal of Metamorphic Geology, 15, 203–222. DOI: http://dx.doi.org/10.1111/j.1525-1314.1997.00015.x">10.1111/j.1525-1314.1997.00015.x

Pouchou, J. L. – Pichoir, F. (1985): “PAP” procedure for improved quantitative microanalysis. – Microbeam Analysis, 20, 104–105.

Powell, R. – Holland, T. (1994): Optimal geothermometry and geobarometry. – American Mineralogist, 79, 120–133.

Racek, M. – Štípská, P. – Pitra, P. – Schulmann, K. – Lexa, O. (2006): Metamorphic record of burial and exhumation of orogenic lower and middle crust: a new tectonothermal model for the Drosendorf window (Bohemian Massif, Austria). – Mineralogy and Petrology, 86, 221–251. DOI: http://dx.doi.org/10.1007/s00710-005-0111-7">10.1007/s00710-005-0111-7

Ulrych, J. – Ackerman, L. – Kachlík, V. – Hegner, E. – Balogh, K. – Langrová, A. – Luna, J. – Fediuk, F. – Lang, M. – Filip, J. (2010): Constraints on the origin of gabbroic rocks from the Moldanubian-Moravian units boundary (Bohemian Massif, Czech Republic and Austria). – Geologica Carpathica, 61(3), 175–191.

Weiss, J. (1966): Ultrabasic rocks of the West Moravian Crystalline complex. – Krystalinikum, 4, 171–184.

Whitney, D. L. – Evans, B. W. (2010): Abbreviations for names of rock-forming minerals. – American Mineralogist, 95(1), 185–187. DOI: http://dx.doi.org/10.2138/am.2010.3371">10.2138/am.2010.3371

Witt-Eickschen, G. E. – Seck, H. A. (1991): Solubility of Ca and Al in orthopyroxene from spinel peridotite: an improved version of an empirical geothermometer. – Contributions to Mineralogy and Petrology, 106, 431–439. DOI: http://dx.doi.org/10.1007/BF00321986">10.1007/BF00321986

Metriky

298

Views

155

PDF views