Multiple fluid migration events and REE+Th mineralisation during Alpine metamorphism in the Sopron micaschist from the Eastern-Alps (Sopron area, Western Hungary)
Abstract
Four fluid migration events were recorded during the Alpine metamorphism in the Sopron micaschist from the Grob gneiss series of the Lower Austroalpine Unit of the Eastern Alps near Sopron, using mineral chemistry data, geothermo-barometry and fluid inclusion studies.
1. Tourmaline mineralisation in quartz veins and to some extent in the host rock. Similar mineral compositions in the quartz-tourmaline veins and in the host rock show equilibrium between fluid and the host rock. Geothermo-barometry gives 560-610oC temperature and 950-1230 MPa pressure for the formation of quartz-tourmaline veins which is the same as the determined P-T peak (T=560 and 600°C p= 840-1230 MPa).
2. Fluids causing Mg-metasomatism in the shear zones. The result of this fluid invasion was the formation of leucophyllite in the shear zones and Mg-enrichment of some minerals (chlorite, muscovite, garnet) in the close vicinity of the shear zone. The effect of this fluid was confined to the shear zones and the neighbouring host rock.
3. The rock was infiltrated along the shear zones and quartz veins with CO2-bearing hypersaline fluids during retrograde metamorphism. The presence of this fluid is evidenced by secondary CO2 inclusions and hypersaline aqueous fluid inclusions ± CO2. The aqueous fluid had high concentrations of Na, Ca, Fe, Al, Cl and contained moderate amounts of Mg, Zn, Ti, K, Mn, S and P. This fluid was the carrier of the REE and Th and locally precipitated florencite, monazite, allanite, apatite, thorite and thorianite in the shear zone. Traces of this mineralisation are found in quartz-tourmaline veins, postdating the tourmaline mineralisation.
4. Late retrograde metamorphic fluid represented by two phase (liquid+vapor) aqueous inclusions of the NaCl-CaCl2-H2O system with total salinity between 25 and 28.5% and homogenisation temperatures between 229.6 and 322oC
References
BALOGH, K. & DUNKL, I. 2005. Argon and fission track dating of Alpine metamorphism and basement exhumation in the Sopron Mts. (Eastern Alps, Hungary): thermochronology or mineral growth? − Mineralogy and Petrology 83, 191-218. https://doi.org/10.1007/s00710-004-0066-0
BERMAN, R.G., 1990. Mixing properties of Ca-Mg-Fe-Mn garnets. − American Mineralogist 75, 328-344.
DAVIS, D.W., LOWENSTEIN, T.K. & SPENCER, R.J., 1990. Melting behavior of fluid inclusions in laboratory-grown halite crystals in the system NaCl-H2O, NaCl-KCl-H2O, NaCl-MgCl2-H2O and NaCl-CaCl2-H2O. − Geochimica et Cosmochimica Acta 54, 591-601. https://doi.org/10.1016/0016-7037(90)90355-o
DEMÉNY, A., SHARP Z.D. & PFEIFER H-R. 1997. Mg metasomatism and formation conditions of Mg-chlorite-muscovite-quartzphyllites (leucophyllites) of the Eastern Alps (W. Hungary) and their relations to Alpine whiteschists. − Contributions to Mineralogy and Petrology 128, 247-260. https://doi.org/10.1007/s004100050306
DICKENSON, M.P. & HEWITT, D. 1986. A garnet-chlorite geothermometer. − Geological Society of America, Abstracts with Program 18, 584.
DRAGANITS, E., 1998. Two crystalline series of the Sopron Hills (Burgenland) and their correlation to the lower Austroalpine in Eastern Austria. − Jahrbuch der Geologischen Bundesanstalt 141, 113-146 (in German with English abstract).
FAZEKAS, V., KÓSA, L. & SELMECZI, B. 1975. Rare-earth element mineralisation in the crystalline schists of the Sopron Mountains. − Földtani Közlöny 105, 297-308 (in Hungarian with English abstract).
FERRY, J.M. & SPEAR, F.S. 1978. Experimental calibration of the partitioning of Fe and Mg between biotite and garnet. − Contributions to Mineralogy and Petrology 66, 113-117. https://doi.org/10.1007/bf00372150
GREEN, T.H. & HELLMAN, P.L. 1982. Fe-Mg partitioning between coexisting garnet and phengite at high pressure and comments on a garnet-phengite geothermometer. − Lithos 15, 253-266. https://doi.org/10.1016/0024-4937(82)90017-2
GREGUREK, D., ABART, R. & HOINKES, G. 1997. Contrasting Eoalpine P-T evolutions in the southern Koralpe, Eastern Alps. − Mineralogy and Petrology 60, 61-80. https://doi.org/10.1007/bf01163135
HODGES, K.V. & CROWLEY, P.D. 1985. Error estimation and empirical geothermobarometry for pelitic systems. − American Mineralogist 70, 702-709.
KERTÉSZ, ZS., FURU, E., ANGYAL, A., FREILER, Á., TÖRÖK, K. & HORVÁTH, Á. (2015) Characterization of uranium and thorium containing minerals by nuclear microscopy. − Journal of Radioanalytical and Nuclear Chemistry. 306, 283–288. https://doi.org/10.1007/s10967-015-4175-5 DOI 10.1007/s10967-015-4175-5
KISHÁZI, P. & IVANCSICS J. 1985. Genetic petrology of the Sopron Crystalline schist sequence. − Acta Geologica Hungarica 28, 191-213.
KISHÁZI, P. & IVANCSICS J. 1987. Genetic petrology of the Sopron Micaschist Formation. − Földtani Közlöny, 117, 203-221 (in Hungarian with English abstract).
KISHÁZI, P. & IVANCSICS, J. 1989. Petrogenesis of the Sopron Gneiss Formation. − Földtani Közlöny, 119, pp. 153-166.
LELKES-FELVÁRI, GY., SASSI, F.P. & VISONÁ, D. 1984. Pre-Alpine and Alpine developments of the Austridic basement in the Sopron area (Eastern Alps, Hungary). − Rendiconti della Societá Italiana di Mineralogia e Petrologia 39, 593-612.
MILLER, C. 1990. Petrology of the type locality eclogites from the Koralpe and Saualpe (Eastern Alps) Austria. − Schweizerische Mineralogische und Petrographische Mitteilungen 70, 287-300.
NAGY, G., DRAGANITS, E., DEMÉNY, A., PANTÓ, GY. & ÁRKAI, P. 2002. Genesis and transformations of monazite, florencite and rhabdophane during medium grade metamorphism:examples from the Sopron Hills, Eastern Alps. − Chemical Geology 191 (1-3), 25-46. https://doi.org/10.1016/s0009-2541(02)00147-x
NEUBAUER, F., DALLMEYER, R.D. & TAKASU, A. 1999. Conditions of eclogite formation and age of retrogression within the Sieggraben unit, Eastern Alps: Implications for Alpine-Carpathian tectonics. − Schweizerische Mineralogische und Petrographische Mitteilungen 79, 297-307.
OAKES, C.S., BODNAR, R.J. & SIMONSON, T.M. 1990. The system NaCl-CaCl2-H2O: I. The ice liquidus at 1 atm total pressure. − Geochimica et Cosmochimica Acta, 54, 603-610. https://doi.org/10.1016/0016-7037(90)90356-p
OLSEN, S.N. 1987. The composition and role of the fluid in migmatites: a fluid inclusion study of the Front Range rocks. − Contributions to Mineralogy and Petrology 96, 104-120. https://doi.org/10.1007/bf00375531
PROCHASKA, W., HUBER, M. & BECHTEL, A. 1997. Alpidic formation of leucophyllite at the eastern margin of the Alps. − Archiv für Lagerstättenforschung der Geologischen Bundesanstalt 20, 37-52. (in German with English abstract).
SCHUSTER, R. & THÖNI, M. 2001. Austroalpine basement units (AAB). In Dunkl, I., Balintoni, I., Frisch, W., Janák, M., Koroknai, B., Milovanovic, D., Pamic, J., Székely, B., Vrabec, M. (eds) Metamorphic map and database of Carpatho-Balkan-Dinaride area. − http://www.met-map.uni-goettingen.de
SPRÁNITZ, T., JÓZSA, S., KOVÁCS, Z., VÁCZI, B. & TÖRÖK, K. 2018. Magmatic and metamorphic evolution of tourmaline-rich rocks of the Sopron area, Eastern Alps. − Journal of Geosciences 63, 175 – 191. https://doi.org/10.3190/jgeosci.263 DOI: 10.3190/jgeosci.263.
THÖNI, M. 1999. A review of geochronological data from the Eastern Alps. − Schweizerische Mineralogische und Petrographische Mitteilungen 79, 209-230.
TOLLMANN, A. 1977. Geologie von Österreich. Band I. Die Zentralalpen. Deuticke, Vienna.
TÖRÖK, K. 1996. High-pressure/low temperature metamorphism of the Kő-hegy gneiss, Sopron (W-Hungary); Phengite barometry and fluid inclusions. − European Journal of Mineralogy 8, 917-925. https://doi.org/10.1127/ejm/8/5/0917
TÖRÖK, K. 1998. Magmatic and high-pressure metamorphic development of orthogneisses in the Sopron area, Eastern Alps (W-Hungary) − Neues Jahrbuch für Mineralogie Abhandlungen 173, 63-91.
TÖRÖK, K. 1999. Pre-Alpine development of the andalusite-sillimanite-biotite-schist from the Sopron-Mountains (Eastern Alps, W-Hungary). − Acta Geologica Hungarica 42, 127-160.
TÖRÖK, K. 2001. Multiple fluid migration events in the Sopron Gneisses during the Alpine high-pressure metamorphism, as recorded by bulk-rock and mineral chemistry and fluid inclusions. − Neues Jahrbuch für Mineralogie Abhandlungen 177 (1), 1-36. https://doi.org/10.1127/007777502753418566
TÖRÖK, K. 2003. Alpine P-T path of micaschists and related orthogneiss veins near Óbrennberg (W-Hungary, Eastern Alps). − Neues Jahrbuch für Mineralogie Abhandlungen 179, 101-142. https://doi.org/10.1127/0077-7757/2003/0179-0101
VANKO, D.A., BODNAR, R.J. & STERNER, M.A. 1988. Synthetic fluid inclusions: VIII. Vapor saturated halite solubility in part of the system NaCl-CaCl2-H2O, with application to fluid inclusions from oceanic hydrothermal systems. − Geochimica et Cosmochimica Acta 52, 2451-2456. https://doi.org/10.1016/0016-7037(88)90303-1
VINCZE, J., FAZEKAS, V. & KÓSA, L. 1996. Uranium-thorium-rare earth mineralisations in the crystalline schist series, Fertőrákos, Sopron Mts., NW-Hungary. − Földtani Közlöny 126, 359-417. (in Hungarian with English Abstract)
WANG, P. & SPEAR, F.S. 1991. A field and theoretical analysis of garnet+chlorite+chloritoid+biotite assemblages from the tri-state (MA, CT, NY) area, USA. − Contributions to Mineralogy and Petrology 106, 217-235. https://doi.org/10.1007/bf00306435
YANATIEVA, O.K. 1946. Polythermal solubilities in the systems CaCl2-MgCl2-H2O and CaCl2-NaCl-H2O. − Zhurnal Prikladnoi Khimii 19, 709-722 (in Russian).
