Quantitative structural analyses and numerical modelling of ...

EXTRUSIONOFLOWERCRUSTINVARISCANOROGEN 57Fig. 3. Relevant P–T data from Bohemiangranulites and surrounding metasedimentaryrocks; from the Moldanubian domain,if not specified from some other unitbelow. The P–T data and related radiometricages (Ma) are assembled from thepublications 1–11, according to the labelsat each polygon. Citations for P–T data –1, Kalt et al. (1999); 2, Kotkova´ (1993) –Eger Crystalline Complex; 3, Kro¨ ner et al.(2000); 4, Linner (1996); 5, Pitra et al.(1999); 6, Racek et al. (2006); 7, Sˇtı´pska´et al. (2004); 8, Sˇtı´pská & Powell (2005);9, Tajcˇmanova´ et al. (2006); 10, Verneret al. (2008); 11, Ro¨ tzler & Romer (2001) –Saxonian Granulites. Citations forgeochronology: 1, Kalt et al. (1997); 2,Kotkova´ et al. (1996) – Eger CrystallineComplex; 3, Kro¨ ner et al. (2000); 5,Gebauer et al. (1989); 7, Sˇtı´pska´ et al.(2004); 9, Schulmann et al. (2005); 10,Verner et al. (2008); 11, Romer & Ro¨ tzler(2001) – Saxonian Granulites.Moldanubian geochronologyMost of the existing U–Pb zircon ages from theBohemian Massif granulites cluster at c. 340 Ma(Fig. 2; for review, see e.g. Janousˇek & Holub, 2007),interpreted as a time of HP metamorphism and subsequentretrogression. The older ages, widely scatteredbetween 450 and 350 Ma, are interpreted usually asprotolith ages (e.g. Wendt et al., 1994; Kro¨ ner et al.,2000; Friedl et al., 2003). Sm–Nd garnet data revealslightly older ages than 340 Ma (e.g. Prince et al.,2000), but their significance is problematic (Romer &Ro¨ tzler, 2001). Janousˇek et al. (2004) suggested anOrdovician granitic protolith with a model age ofc. 450 Ma for the Variscan felsic granulites, supportedalso by radiometric U–Pb zircon ages of Kro¨ ner et al.(2000) and Friedl et al. (2004). The Rb–Sr biotite andmuscovite cooling ages span between 330 and 310 Ma(Van Breemen et al., 1982; Svojtka et al., 2002) similarto 40 Ar– 39 Ar ages on amphibole, muscovite and biotite(Kosˇler et al., 1999). The exposed Moldanubian rocksreached the surface during the Permian, when theywere locally covered by undeformed sedimentaryrocks. Moldanubian Varied and Monotonous Groupsrecord metamorphic events from 355 ± 2 Ma (U–Pbon sphene, Wendt et al., 1993) or the 367 ± 19 Ma forthe Kaplice paragneiss (U–Pb on zircon, Kro¨ ner et al.,1988). A minimum age for the ductile deformationis restricted by syndeformational pegmatites that yieldan age of 331 ± 5 Ma (Rb–Sr on muscovite, VanBreemen et al., 1982).There is a range of syn- to post-tectonic granitoidsintruded into the Moldanubian rocks. The oldest calcalkalineintrusions of the Central Bohemian PlutonicComplex were syntectonically emplaced into uppercrustallevels during regional transpression from c. 354Ó 2010 Blackwell Publishing Ltd209