Abstract
In an attempt to better constrain the timing of Variscan HP-HT metamorphism in the SE Bohemian Massif we have dated zoned zircons from a garnet-kyanite granulite of granitic composition from the Dunkelsteiner Wald Massif, Lower Austria, by means of sensitive high-resolution ion microprobe (SHRIMP) technique. In order to combine isotopic information with crystal growth textures, CL and BSE images were systematically taken from the dated zircons. A characteristic threefold concentric zoning was found in many zircons. This involves pre-Variscan protolithic cores followed by two distinct metamorphic/anatectic overgrowth shells of Variscan age. The inner overgrowth shell is characterized by a weak CL but bright BSE signal, and yields high contents of uranium (0.1 to 0.2 wt.%). A pooled U-Pb Concordia age for this zone is 342.0 ± 3.0 Ma (n = 11, MSWD = 0.12). The second, outer, overgrowth shell is always bright in the CL image, dark in the BSE image, and has generally low uranium contents (mostly <500 ppm). A pooled U-Pb Concordia age for this zone is 337.1 ± 2.7 Ma (n = 11, MSWD = 0.22). These results imply that the Variscan HT crystallisation history of the Moldanubian granulites took place over a period of a few million years and was not an extremely rapid subduction-exhumation process.
SHRIMP measurements in the protolithic cores yield a cluster of (sub)concordant ages between ∼390 and 460 Ma and a few outliers at higher ages mostly represented by cores in cores. Core domains, which are large, homogeneous and with undisturbed igneous oscillatory zoning, yielded preferentially ages between 430 and 460 Ma. We therefore consider that granitic protolith formation took place at that time. The still older inner cores are interpreted as inherited into the granitic melt.
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References
Becker RH (1997) Sm-Nd-garnet ages and cooling history of high-temperature garnet peridotite massifs and high-pressure granulites from Lower Austria. Contrib Mineral Petrol 127:224–236
Carswell DA (1991) Variscan high P-T metamorphism and uplift history in the Moldanubian Zone of the Bohemian Massif in Lower Austria. Eur J Mineral 3:323–342
Carswell DA, Jamtveit B (1990) Variscan Sm-Nd ages for the high-pressure metamorphism in the Moldanubian Zone of the Bohemian Massif, Lower Austria. N Jahrb Mineral Abh 162:69–78
Carswell DA, O’Brien PJ (1993) Thermobarometry and geotectonic significance of high-pressure granulites: examples from the Moldanubian Zone of the Bohemian Massif in Lower Austria. J Petrol 34:427–459
Compston W, Williams IS, Meyer C (1984) U-Pb geochronology of zircons from Lunar Breccie 73217 using a sensitive high mass-resolution ion microprobe. J Geophys Res 89:B525–B534
Cooke RA (2000) High-pressure/temperature metamorphism in the St. Leonhard Granulite Massif, Austria: evidence from intermediate pyroxene-bearing granulites. Int J Earth Sci 89:631–651
Cooke RA, O’Brien PJ (2001) Resolving the relationship between high p-T rocks and gneisses in collisional terranes: an example from the Gföhl gneiss-granulite association in the Moldanubian zone, Austria. Lithos 58:33–54
Cooke RA, O’Brien PJ, Carswell DA (2000) Garnet zoning and the identification of equilibrium mineral compositions in high-pressure-temperature granulites from the Moldanubian Zone, Austria. J Metamorph Geol 18:551–569
Dallmeyer RD, Neubauer F, Höck V (1992) Chronology of Late Paleozoic tectonothermal activity in the northeastern Bohemian Massif, Austria (Moldanubian and Moravo-Silesian zone): 40Ar/39Ar mineral age controls. Tectonophy 210:135–153
Faryad SW, Nahodilová R, Dolejs D (2010) Incipient eclogite facies metamorphism in the Moldanubian granulites revealed by mineral inclusions in garnet. Lithos 144:54–69
Fiala J, Matějovská O, Vaňková V (1987) Moldanubian granulites: source material and petrogenetic considerations. Neues Jahrb Mineral Abh 157:133–165
Finger F, Steyrer HP (1995) A tectonic model for the eastern Variscides: indications from a chemical study of amphibolites in the southeastern Bohemian Massif. Geol Carpath 46:137–150
Finger F, von Quadt A (1995) U/Pb ages of zircons from a plagiogranite-gneiss in the south-eastern Bohemian Massif, Austria—further evidence for an important early Paleozoic rifting episode in the eastern Variscides. Schweiz Mineral Petrogr Mitt 75:265–270
Finger F, Roberts MP, Pöschl-Otrel K, Haunschmid B (1996) Anzeichen für partielle Anatexis und späte Zirkonkristallisation in Moldanubischen Hochdruck-Granuliten aus Niederösterreich. Terra Nova 96:48–51
Finger F, Gerdes A, Janoušek V, René M, Riegler G (2007) Resolving the Variscan evolution of the Moldanubian sector of the Bohemian Massif: the significance of the Bavarian and the Moravo-Moldanubian tectonometamorphic phases. J Geosci 52:9–28
Franěk J, Schulmann K, Lexa O (2006) Kinematic and rheological model of exhumation of high pressure granulites in the Variscan orogenic root: example of the Blanský les granulite, Bohemian Massif, Czech Republic. Mineral Petrol 86:253–276
Franke W (1989) Tectonostratigraphic units in the Variscan belt of central Europe. In: Dallmeyer RD (ed) Terranes in the circum-Atlantic Paleozoic orogens. Geol Soc Am Spec Pap. pp 67–90
Franke W (2000) The middle-European segment of the Variscides: tectonostratigraphic units, terrane boundaries and plate tectonic evolution. In: Franke W, Haak U, Oncken O, Tanner D (eds) Orogenic processes: quantification and modelling in the Variscan belt. Geol Soc Spec Publ 179:35–61
Friedl G, Von Quadt A, Finger F (1994) 340 Ma U/Pb Monazitalter aus dem niederöster-reichischen Moldanubikum und ihre geologische Bedeutung. Terra Nostra 3(94):43–46
Friedl G, Finger F, Paquette JL, von Quadt A, McNaughton NJ, Fletcher IR (2004) Pre-Variscan geological events in the Austrian part pf the Bohemian Massif deduced from U-Pb zircon ages. Int J Earth Sci 93:802–823
Fuchs G (1976) Zur Entwicklung der Böhmischen Masse. Jb Geol BA 129:41–49
Fuchs G, Matura A (1976) Zur Geologie des Kristallins der südlichen Böhmischen Masse. Jb Geol BA 119:1–43
Hermann J, Spandler C, Hack A, Korsakov AV (2006) Aqueous fluids and hydrous melts in high-pressure and ultrahigh pressure rocks: implications for element transfer in subduction zones. Lithos 92:399–417
Hoppe G (1966) Zirkone aus Granuliten. Ber dt Ges Geol Wiss, B Miner Lagerstättenf 11:47–81
Hoskin PWO, Schaltegger U (2003) The composition of zircon and igneous and metamorphic petrogenesis. Rev Mineral Geochem 53:27–55
Janoušek V, Holub FV (2007) The causal link between HP-HT metamorphism and ultrapotassic magmatism in collisional orogens: case study from the Moldanubian Zone of the Bohemian Massif. Proc Geol Assoc 118:1–12
Janoušek V, Finger F, Roberts MP, Frýda J, Pin C, Dolejš D (2004) Deciphering petrogenesis of deeply buried granites: whole-rock geochemical constraints on the origin of largely undepleted felsic granulites from the Moldanubian Zone of the Bohemian Massif. Trans Roy Soc Edinb Earth Sci 95:141–159
Janoušek V, Gerdes A, Vrana S, Finger F, Erban V, Friedl G, Braithwaite CJR (2006) Low-pressure granulites of the Lišov Massif, Southern Bohemia: Visean metamorphism of Late Devonian plutonic arc rocks. J Petrol 47:705–744
Keppler H, Wyllie PJ (1990) Role of fluids in transport and fractionation of uranium and thorium in magmatic provinces. Nature 348:531–533
Kotková J, Harley SL (1999) Formation and evolution of highpressure leucogranulites: experimental constraints and unresolved issues. Phys Chem Earth, Solid Earth Geod 24:299–304
Kotková J, Harley SL (2010) Anatexis during high-pressure crustal metamorphism: evidence from garnet-whole-rock REE relationships and zircon-rutile Ti-Zr thermometry in leucogranulites from the Bohemian Massif. J Petrol 51:1967–2001
Kotková J, Gerdes A, Parrish R, Novak M (2007) Clasts of Variscan high-grade rocks within Upper Visean conglomerates. Constraints on exhumation history from petrology and U-Pb chronology. J Metamorph Geol 25:781–801
Krenn E, Finger F (2010) Unusually Y-rich monazite-(Ce) with 6–14 wt.% Y2O3 in a granulite from the Bohemian Massif: implications for high temperature monazite growth from the monazite-xenotime miscibility gap thermometry. Mineral Mag 74:217–225
Kröner A, O’Brien PJ, Nemchin AA, Pidgeon RT (2000) Zircon ages for high pressure granulites from South Bohemia, Czech Republic, and their connection to Carboniferous high temperature processes. Contrib Mineral Petrol 138:127–142
Kryza R, Pin C, Vielzeuf D (1996) High-pressure granulites from the Sudetes (south-west Poland): evidence of crustal subduction and collision thickening in the Variscan belt. J Metamorph Geol 14:531–546
Linner M (1996) Metamorphism and partial melting of paragneisses of the Monotonous Group, SE Moldanubicum (Austria). Mineral Petrol 58:215–234
Ludwig KR (2003) User’s manual for Isoplot 3.00: a geochronological toolkit for Microsoft Excel: Berkeley Geochronology Center, Special Publ 4:71 pp
Matte P, Maluski H, Echtler H (1985) Variscan eastward ductile shearing in the Waldviertel nappes (South eastern Bohemian Massif, Austria)—39Ar/40Ar data. Comptes Rendus de l’academie des Sciences serie II 301:721
Matte P, Maluski H, Rajlich P, Franke W (1990) Terrane boundaries in the Bohemian Massif: Result of large-scale Variscan shearing. Tectonophysics 177:151–170
Miller CF, McDowell SM, Mapes RW (2003) Hot and cold granites? Implications of zircon saturation temperatures and preservation of inheritance. Geology 31:529–532
Morishita T, Arai S, Ishida Y (2007) Trace element compositions of jadeite (+omphacite) in jadeitites from the Itoigawa-Ohmi district, Japan: implications for fluid processes in subduction zones. Island Arc 16:40–56
Neumann W (1984) Zur erdgeschichtlichen Entwicklung des sächsischen Granulitmassivs. Z Angew Geol 30:183–190
Novák M, Černý P, Kimbrough DL, Taylor MC, Ercit TS (1998) U-Pb Ages of monazite from granitic pegmatites in the Moldanubicum and their geological implications. Acta Univ Carol Geol 42:309–310
O’Brien PJ, Carswell DA (1993) Tectonometamorphic evolution of the Bohemian Massif: evidence from high-P metamorphic rocks. Geol Rundsch 82:531–555
O’Brien PJ, Rötzler J (2003) High-pressure granulites: formation, recovery of peak conditions and implications for tectonics. J Metamorph Geol 2:3–20
O’Brien PJ (2000) The fundamental Variscan problem: high-temperature metamorphism at different depths and high-pressure metamorphism at different temperatures. In: Franke W, Haak V, Oncken O, Tanner D (eds) Orogenic processes: quantification and modelling in the Variscan belt. Geol Soc London Spec Publ 179:369–386
Pin C, Vielzeuf D (1983) Granulites and related rocks in Variscan median Europe: a dualistic interpretation. Tectonophysics 93:47–74
Pöschl-Otrel K (1995) Untersuchungen an Zirkonen aus Granuliten des niederösterreichischen Waldviertels. MSc thesis, University of Salzburg
Putnis A (2002) Mineral replacement reactions: from macroscopic observations to microscopic machanisms. Mineral Mag 66:689–708
Putnis A (2009) Mineral replacement reactions. Thermodynamics and kinetics of water-rock interaction. Rev Mineral Geochem 70:87–124
Roberts MP, Finger F (1997) Do U-Pb zircon ages from granulites reflect peak metamorphic conditions? Geology 25:319–322
Rubatto D (2002) Zircon trace element geochemistry: partitioning with garnet and the link between U-Pb ages and metamorphism. Chem Geol 184:123–138
Schaltegger U, Fanning CM, Günther D, Maurin JC, Schulmann K, Gebauer D (1999) Growth, annealing and recrystallization of zircon and preservation of monazite in high-grade metamorphism: conventional and in-situ U-Pb isotope, cathodoluminescence and microchemical evidence. Contrib Mineral Petrol 134:186–201
Schaltegger U, Brack P, Ovtcharova M, Peytcheva I, Schoene B, Stracke A, Marocchi M, Bargossi GM (2009) Zircon and titanite recording 1.5 million years of magma accretion, crystallization and initial cooling in a composite pluton (southern Adamello batholith, northern Italy). Earth Planet Sci Lett 286:208–218
Scharbert HG (1963) Die Granulite der südlichen niederösterreichen Moldanubikums I. Neues Jb Mineral Abh 100:59–86
Scharbert HG, Kurat G (1974) Distribution of some elements between coexisting ferromagnesian minerals in Moldanubian granulite facies rocks, Lower Austria, Austria. Tschermaks Mineral Petrogr Mitt 21:110–134
Schenk V, Todt W (1983) U-Pb-Datierungen an Zirkon und Monazit der Granulite im Moldanubikum Niederösterreichs (Waldviertel). Fortschr Mineral 61:190–191
Schoene B, Guex J, Bartolini A, Schaltegger U, Blackburn TJ (2010) Correlating the end—Triassic mass extinction and flood basat volcanism at the 100 ka level. Geology 38:387–390
Schulmann K, Konopasek J, Janoušek V, Lexa O, Lardeaux J-M, Edel JB, Stipska P, Ulrich S (2009) An Andean type Palaeozoic convergence in the Bohemian Massif. C R Geosci 341:266–286
Smith JB, Barley ME, Groves DI, Krapez B, McNaughton NJ, Bickle MJ, Chapman HJ (1998) The Scholl shear zone, west Pilbara: evidence for a terrane boundary structure from integrated tectonic analyses, SHRIMP U-Pb dating and isotopic and geochemical data of granitoids. Precamb Res 88:143–171
Stacey JS, Kramers JD (1975) Approximation of terrestrial lead isotope evolution by a two stage model. Earth Planet Sci Lett 26:207–221
Steiger RH, Jäger E (1977) Subcommission on geochronology: convention on the use of decay constants in geo- and cosmochronology. Earth Planet Sci Lett 36:359–362
Tajcmanová L, Konopásek J, Schulmann K (2006) Thermal evolution of the orogenic lower crust during exhumation within a thickened Moldanubian root of the Variscan belt of central Europe. J Metamorph Geol 24:119–134
Tollman A (1982) Großräumiger variszischer Deckenbau im Moldanubikum und neue Gedanken zum Variszikum Europas. Geotekt Forsch 64:1–91
Van Breemen O, Aftalion M, Bowes DR, Dudek A, Misar Z, Povandra P, Vrana S (1982) Geochronological studies of the Bohemian Massif, Czechoslovakia, and their significance in the evolution of Central Europe. Trans Roy Soc Edinb Earth Sci 73:89–108
Vellmer C (1992) Stoffbestand und Petrogenese von Granuliten und granitischen Gesteinen der südlichen Böhmischen Masse in Niederösterreich. PhD thesis. Georg-August University, Göttingen
Vielzeuf D, Pin C (1989) Geodynamic implications of granulitic rocks in the Hercynian belt. In: Daly JS, Cliff RA, Yardley BWD (eds) Evolution of metamorphic belts. Geol Soc Spec Pub 43, pp 343–348
Vrána S, Šrámek J (1999) Geological interpretation of detailed gravity survey of the granulite complex in southern Bohemia and its structure. Bull Geol Surv Prague 74:261–277
Watson EB, Wark DA, Thomas JB (2006) Crystallization thermometers for zircon and rutile. Contrib Mineral Petrol 151:413–433
Wendt JI, Kröner A, Fiala J, Todt W (1994) U-Pb zircon and Sm-Nd dating of Moldanubian HP/HT granulites from South Bohemia, Czech Republic. J Geol Soc Lond 151:83–90
Xia QX, Zheng YF, Hu Z (2010) Trace elements in zircon and coexisting minerals from low –T/UHP metagranite in the Dabie orogen: implications for action of supercritical fluid during continental subduction-zone metamorphism. Lithos 114:385–412
Acknowledgements
Two careful reviews by Javier Rodriguez and Wali Faryad helped to improve this paper and are gratefully acknowledged. Parts of the work were supported through FWF projects P 12248 and P 15133 (to F.F.).
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Friedl, G., Cooke, R.A., Finger, F. et al. Timing of Variscan HP-HT metamorphism in the Moldanubian Zone of the Bohemian Massif: U-Pb SHRIMP dating on multiply zoned zircons from a granulite from the Dunkelsteiner Wald Massif, Lower Austria. Miner Petrol 102, 63 (2011). https://doi.org/10.1007/s00710-011-0162-x
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DOI: https://doi.org/10.1007/s00710-011-0162-x