Vznik metamorfní minerální asociace granátovců z desenské jednotky silezika
Roč.16,(2009)
The usually medium-grained garnetites form up to several cm thick layers in quartz-magnetite mineralizations of the Desná Unit in the Silesicum. The garnetite mineral assemblage consists of epidote, quartz, garnet, magnetite, biotite, ilmenite, apatite and retrograde chlorite. The mineralogical and petrological results demonstrate that garnetites are metamorphosed submarine exhalites. Garnet from the garnetites has compositions with nearly equal amounts of spessartine and almandine components and can by interpreted as result metamorphic reactions partially consuming of the Mn-rich epidote. Thermobarometric calculations from the garnetites yielded peak amphibolite facie metamorphic conditions ca. 540–600 °C and up to 3 kbar. Chemical composition of fluids estimated for this metamorphic event is H2O = 82 až 95 mol. %, CO2 = 4 až 17 mol %, NaCl = 1 až 2 mol. %. The biotite was partially replaced by chlorite during younger retrograde metamorphic event under greenschist facie.
Desná Group; Silesicum; garnet-rich rocks; epidote; metamorpic evolution
Bhattacharya, A. – Mohanty, L. – Maji, A. – Sen, S. K. – Raith, M. (1992): Non-ideal mixing in the phlogopite–annite-binary: constraints from experimental data on Mg–Fe partitioning and a reformulation of the biotite–garnet geothermometer. – Contrib. Mineral. petrol 111 1, pp. 87–93.
Bodnar, R. J. (1993): Revised equation and table for determining the freezing point depression of H2O-NaCl solutions. – Geochim. Cosmochim. Acta, 57, 683–684.
Bowers, T. S., Helgeson, H. C. (1983): Calculation of the thermodynamic and geochemical consequences of nonideal mixing in the system H2O-CO2-NaCl on phase relations in geologic systems: equation of state for H2O-CO2-NaCl fluids at high pressures and temperatures. – Geochim. Cosmochim. Acta, 47, 1247–1275.
Brown, Ph.E. (1989): FLINCOR: A fluid inclusion data reduction and exploration program (abstr.). – Second biennial Pan-American conference on reasearch on fluid inclusions, program with abstracts: 14.
Buriánek, D., Otava, J. (2007): Tři geneticky rozdílné typy granátovců z hlinské zóny a poličského krystalinika. Acta Musei Moraviae, Scientae geologicae 92, 143–150.
Fleet, A. J. (1983): Hydrothermal and hydrogenous ferro-manganese deposits: do they form a continuum? The rare earth elements evidence. – In: Rona, P. A. – Boström, K. – Laubier, L. – Smith, K. L. (eds.): Hydrothermal processes at seafloor spreading centers, Plenum Press, New York, pp 535–555.
Fojt, B. (2002): Páskované železné rudy v desenských rulách silezika: přehled názorů na jejich vznik; současný stav poznatků. – Sborník „Mineralogie Českého masivu a Západních Karpat 2002“, 17–24. Vydavatelství UP Olomouc.
Grygar, R. – Vavro, M. (1995): Evolution of Lugosilesian Orocline (North-eastern periphery of the Bohemian Massif): Kinematics of Variscan deformation. – Journ. Czech Geol. Soc., 40: 65–90. Praha.
Cháb, J. – Fediuková, E. – Fišera, M. – Novotný, P. – Opletal, M. (1990): Variská orogeneze v sileziku. – Sbor. geol. Věd. Lož. geol. Mineral., 29: 9–39.
Keskinen, M – Liou, J. G. (1987): Stability relations of manganese-iron-aluminum piemontite. – J Metamorphic Geol 5: 495–507.
Kretschmer, F. (1911): Das metamorphe Diorit- und Gabbromassiv in der Umgebung von Zöptau (Mähren). – Jb. Geol. Reichsanst., 61, 53–179. Wien.
Kröner, A. – Štípská, P. – Schulmann, K. – Jaeckel, P. (2000): Chronological constraints on the pre-Variscan evolution of the northeastern margin of the Bohemian Massif, Czech Republic. –In: Franke, W. – Haak, V. – Oncken, O. – Tanner, D. (eds): Orogenetic Processes: Quantification and Modelling in the Variscan Belt. Geological Sociaty. London. Special Publications, 179: 175–197.
Liou, J. G. (1973): Synthesis and stability relations of epidote, Ca2Al3FeSi3O12(OH). J Petrol 14:381–413.
Mücke, A. – Losos, Z. (2000): Polymorfně přepracované, páskované a silicifikované magnetitové rudy v desenských rulách (silesikum, Česká republika). – Acta Mus. Moraviae, Sci. Geol., 85, 47–80. Brno.
Mücke, A. – Losos, Z. (2007): The magnetite mineralizations of the Desná Group in the Silesicum, Czech Republic: petrographic, mineralogical, and geochemical studies and their genetic implications. – Journal of Geosciences, 52 (2007), 227–270.
Petrík, I. – Broska, I. – Lipka, J. – Siman, P. (1995) Granitoid Allanite – (Ce) Substitution Relations, Redox Conditions and REE Distributions (on an Example of I-Type Granitoids, Western Carpathians, Slovakia). Geologica Carpathica 46: 79–94
Plimer, I. R. (1984): The mineralogical history of the Broken Hill lode, N.S.W. Australian Journal of Earth Sciences 31, 379–402.
Pouba, Z. (1951): Zpráva o výzkumu železných rud v jádru desenské klenby. – Věst. Ústř. Úst. geol., 27, 227–231. Praha.
Pouba, Z. (1970): Pre-Cambrian banded magnetite ores of the Desná Dome. – Sbor. geol. Věd, ložisk. Geol., 12, 7–64. Praha.
Roedder, E. (1984): Fluid inclusions. Rev. Mineral., 12, 1–644.
Sellner, F. (1930): Die Magnetitlagerstätten der tschecho-slowakischen Republik. III. Die Vorkommen im Altvatergebirge. A) Mönchenschächte bei Winkelsdorf. – Z. prakt. Geol., 38, 7, 97–104. Berlin.
Shepherd, T. J. – Rankin, A. H. – Alderton, D. H. M. (1985): A practical guide to fluid inclusion studies. – Blackie. Glasgow and London.
Wing, B. – Ferry, J. M. – Harrison, T. M. (2003): Prograde destruction and formation of monazite and allanite during contact and regional metamorphism of pelites: petrology and geochronology. – Contrib. Mineral. Petrol. 145 (2003), pp. 228–250.
Zhang, Y. G. – Frantz, J. D. (1987): Determination of the homogenization temperatures and densities of supercritical fluids in the system NaCl-KCl-CaCl2-H2O using synthetic fluid inclusions. - Chem. Geol., 64, 335–350.
Zimák, J. – Fojt, B. (2002): Vernířovice – Zadní Hutisko. Železné rudy typu BIF v desenských rulách. – In: Zimák, J. – Novotný, P. – Fojt, B. – Novák, M. – Vávra, V. – Kopa, D. – Losos, Z. – Prinzová, E. – Skácel, J.: Exkurzní průvodce po mineralogických lokalitách na Sobotínsku, 61–65. Vydavatelství UP Olomouc.
Zimák, J. (2002): Vernířovice – Jelení hřbet. Železné rudy typu BIF v desenských rulách. – In: Zimák, J. – Novotný, P. – Fojt, B. – Novák, M. – Vávra, V. – Kopa, D. – Losos, Z. – Prinzová, E. – Skácel, J.: Exkurzní průvodce po mineralogických lokalitách na Sobotínsku, 66–69. Vydavatelství UP Olomouc.