U-Pb zircon and Sm-Nd dating of Moldanubian H P /H T granulites from South ohemia, Czech Republic

Conventional multigrain U-Pb systematics of zircon and single-grain evaporation data of zircons in combination with Nd model ages are presented for pyroxene-free, felsic, garnetiferous granulites and orthopyroxene-bearing granulites of felsic, mafic and intermediate composition from the Blansky Lés mountains granulite complex, S Bohemia. Zircons from mafic and intermediate granulites yield Concordia intercept ages between 346 ± 5 and 351 ± 6 Ma as well as a single-grain evaporation age of 346 ± 12 Ma. These ages define the time of Variscan high-grade metamorphism in S Bohemia and are supported by an internal Sm-Nd garnet-zircon-plagioclase-whole rock isochron age of 343 ± 21 Ma. Euhedral zircons from felsic granulites of probable granitic derivation yield U-Pb ages of 366 ± 5 Ma and 373 ± 12 Ma interpreted as intrusion ages of the granitic precursor. An inherited Proterozoic crustal component is documented by poorly defined Concordia upper intercept ages around 1700 Ma and Nd-model ages between 1.3 and 2.1 Ga.