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Abstract Four metasedimentary zircon populations from different tectonometamorphic units of the Central and the Northern Schwarzwald (Variscan belt, SWGermany) were investigated using SEM, cathodoluminescence and SHRIMP dating. Despite partially strong modifications of primary internal morphologies during Variscan metamorphism at amphibolite (750 °C, 0.40.6 GPa) and granulite-facies conditions (950-1,000 °C, 1.4-1.8 GPa), many grains show well-preserved protolith ages. The detritus indicates a northern Gondwana origin and different Palaeozoic episodes of sediment deposition and consolidation. Two of the studied sediments were deposited in Cambrian/early-Ordovician times and consolidated in positions close to northern Gondwana. Late Ordovician and rare Devonian detritus from sediments of two other tectonometamorphic units indicates much later sedimentation close to the leading edge of Gondwana or a terrane assemblage during northern drift towards Laurussia. Subsolidus growth of new zircon due to Variscan granulite facies metamorphism of one of the tectonometamorphic units is precisely dated at 335 ± 2 Ma. [ABSTRACT FROM AUTHOR]

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.