The Vardar zone as a suture for the Mirdita ophiolites, Albania: Constraints from the structural analysis of the Korabi-Pelagonia zone

The Dinarides-Hellenides result from underthrusting of the Adriatic margin during Africa-Europe convergence. In Albania, they consist of (1) a western zone of nappes derived from Adria; (2) a central belt made up of the Mirdita ophiolites; and (3) an eastern zone, the Korabi-Pelagonia zone, of Variscan basement overlain by Permian to Mesozoic rift deposits and carbonates. Some authors interpret the Korabi-Pelagonia zone as a microcontinent between the Mirdita-Pindos oceanic basin to the west and the eastern Vardar oceanic basin to the east; other regard the Korabi-Pelagonia zone as a tectonic window below a single ophiolitic nappe. This contribution argues for a far-traveled thrust sheet. The Mirdita ophiolites are 165-160Ma. The metamorphic sole yielded 40Ar/39Ar ages of 171 to 162Ma. The Korabi-Pelagonia zone is subdivided into the Korabi and Gjegjan subzones. The structural analysis of these rocks supports the rooting of the Mirdita ophiolites in the Western Vardar zone. The post-Variscan cover sequence of the Korabi subzone records two phases of deformation: D-1 is associated with a SE dipping to flat-lying schistosity axial planar to NW verging folds and thrust faults, related to ophiolite obduction; D-2 is a postobduction NNE trending crenulation cleavage. Published zircon fission track analyses yielded 150-125Ma, suggesting that regional metamorphism is Early Cretaceous or older. K-Ar mica ages from correlative rocks of Macedonia cluster between 148 and 130Ma, indicating that D-1 is Late Jurassic. A west directed obduction is favored, as is a rooting east of the Mirdita ophiolites because of the top-to-the-west structural polarity of obduction-related deformation.