Ophiolites from the Grammos-Arrenes area, Northern Greece: geological, paleontological and geochemical data

The Grammos-Arrenes ophiolites between the Pindos Flysch to the east and the Mesohellenic basin to the west represent the northernmost outcrop of the Pindos Ophiolite belt in Greece. The analyses on key outcrops of the Sub-ophiolitic Mélange allow adding new data on the age of the oceanization and on the geochemistry of the effusive products. Basalts samples show a N-MOR affinity and are associated with late Bajocian-early Bathonian radiolarian cherts. The emplacement of the ophiolites onto the sequences of the continental margin is preceded by mass flow deposition of ophiolitic material in the basins facing the advancing ophiolitic nappe. Ophiolite-bearing debris flow deposits and slide blocks are recognized in the Lower Cretaceous deep water sediments of the Beotian Unit and in the upper portion of the Tertiary Pindos Flysch. The intercalations of ophiolitic material in the Beotian flysch before, and in the Pindos Flysch later, are interpreted as the forerunners of the Ophiolitic Nappe which, coming from the Vardar Ocean located to the east, emplaced westward onto the continental margin of Adria. The collected data allow consolidating the constraints for the timing and mechanism of ophiolite emplacement in the Pindos-Grammos area. In addition, taking in consideration the geometry of tectonic stack in the Grammos-Arrenes and the ages of the involved sedimentary deposits it is possible to reconstruct a geodynamic history comparable to the other zones studied along the Dinaric-Hellenic chain