Petrology and evolution of the Hercynian Pieria Granitoid Complex (Thessaly, Greece): paleogeographic and geodynamic implications

The Upper Carboniferous Pieria Granitoid Complex (PGC) and associated Pelagonian basement units are remnants of a Hercynian orogenic belt incorporated into the alpine nappe systems of the central Hellenides. The granitoid rocks range from tonalite to granite and are mildly peraluminous. The lack of significant negative Eu and Sr anomalies suggests insignificant high-level crystal fractionation involving plagioclase. Meta-diorite sheets that cut and are deformed with the granitoids are characterized by metamorphic fabrics. Their trace element signatures are similar to enriched MORB and the high Ba/La is typical of subduction-related mafic rocks. They are interpreted as representing predominantly asthenosphere-derived melts intruded into the granitoids. The bimodal mafic–felsic association observed in the PGC is also found in other plutonic complexes throughout the Flambouron unit of the Pelagonian terrane. Geochemically and isotopically, these plutons resemble Hercynian plutons of western Europe interpreted to result from melting of lower crustal orthogneisses. The Flambouron unit plutons were situated paleogeographically on the northern margin of Gondwana. Mantle enrichment resulted from short-lived subduction during Devonian to early Carboniferous collision of Gondwana and Laurasia, whereas plutonism occurred during regional extension as Gondwana rotated clockwise with respect to Laurasia in the late Carboniferous.