Zircon age dating

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It is noteworthy that acidic and basic magmatism of Neoproterozoic-Lower Cambrian times, in Calabria-Peloritani Terrane, is diachronous being mafic magmatic activity 20-40 Ma older than the acidic one [16-18,7]; both magmatic activity monitored the tectonic evolution of Panafrican orogen from compressional to collapse stages [72].Ordovician-Silurian ages (data ranging from 494±14 to 413±9 Ma) have been recorded in augen gneisses, fine-grained leucocratic gneisses and granulite-facies metabasites from Calabria (Table 1) [16-18, 7, 24].In all samples domains dated 564-593 Ma (n=4) showing magmatic oscillatory zoning and high Th/U ratio (0.16-0.19) are present (Fig. These domains show fractionated REE patterns interpreted as formed in absence of garnet considered as Variscan metamorphic phase [7,70].On this basis a magmatic origin of the zircons indicating the age of protoliths in the time range 564-593 Ma was suggested [17,7].

Only one sample (GO39, Table 1) preserves Devonian-Lower Permian ages interpreted as resetted ages due to thermal input of fluids relased by Late-Variscan plutonites [18].The inherited zircon age patterns in Calabria rocks indicate Gondwana domain pertinence.In particular, the similarities in age and chemistry of the protoliths of Calabria augen gneisses with the acidic magmatites from Anti-Atlas Moroccan domain point to a source derived from a reworking of the West African Craton (WAC) [48] showing similarities with other European Cadomian terranes [62-66].On this basis [23] suggest that the protoliths of augen gneisses were the hosting metasediments in which similar ages were detected.This acidic magmatic activity dated around 543-545 Ma seems to be diffused in the Calabria-Peloritani basement successively than basic magmatism described above.

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