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Presents research on zircon and garnet ages of a mafic granulite from the Variscan belt in the Black Forest of Germany. The isotope closure temperature of garnet Sm-Nd and U-Pb systems; The age of zircon grains found by the U-Pb and evaporation methods; The Sm-Nd and Pb-Pb isochron ages of garnet; Suggestion that many zircons might have lost radiogenic Pb due to metamictization or recrystallisation during the granulite-facies metamorphism at ∼340 Ma; Evidence of pro-grade metamorphism in the garnet Sm-Nd and U-Pb systems; Possibility of a fluid-absence metamorphic environment; Assertion that garnet mineral could be a better candidate than zircon when dating high-grade metamorphism by the U-Pb and Sm-Nd methods.