Age and origin of granitic rocks of the eastern Vardar Zone, Greece: new constraints on the evolution of the Internal Hellenides

摘要

The Vardar Zone is an integral part of the Internal Hellenides and has long been regarded as an ophiolite-decorated suture zone separating two distinct continental blocks, namely the Pelagonian Zone to the west and the Serbo-Macedonian Massif to the east. Several bodies of granites, gneisses and volcanic rocks are associated with the ophiolitic rocks and can provide additional constraints on the evolution of the suture. Single-zircon and monazite dating of felsic rocks yields accurate ages for the processes of accretion of the suture. The igneous formation ages obtained range from 155 to 164 Ma, suggesting an important magmatic phase in the Late Jurassic. The chemical and isotopic composition of these rocks is in accord with their formation in a volcanic-arc setting at an active continental margin. Older continental material incorporated in the Vardar Zone is documented by 319 Ma gneisses and by inherited zircons of mainly Mid-Palaeozoic ages. The Late Jurassic magmatic event overprinted such gneisses, as is evident in monazite ages of 158 Ma. The prevalence of Late Jurassic subduction-related igneous rocks indicates that arc formation and accretion orogeny were the most important processes during the evolution of this part of the Internal Hellenides.