Kinematics and Ophiolite obduction in the Gerania and Helicon Mountains, central Greece

New structural, petrofabric and palaeostress data from the Beotia area (central Greece) were used to investigate the tectonic evolution of the suture zone between the External (Parnassus microplate) and Internal Hellenides (Pelagonian microplate). Petrofabric studies of ultramafic rocks were done using conventional U-stage analysis and the electron backscatter diffraction (EBSD) technique. Detailed structural analysis enabled us to distinguish three main deformation phases that took place from the Triassic to the Eocene. Triassic–Jurassic deformation is related to continental rifting and the progressive formation of an ocean basin. Ophiolites formed above a westward-dipping supra-subduction zone (SSZ) in the Early–Late Jurassic. Trench–margin collision resulted in the southeastward emplacement of the ophiolite nappe over the Pelagonian margin. There is also evidence for a north-westward thrusting of ophiolitic rocks over the Gerania and Helicon units during Berriasian time. This latter tectonic process is closely related to the deposition of “Beotian flysch” into a foreland basin. An extensional phase of deformation accompanied by shallow-water carbonate sedimentation is documented in the Upper Cretaceous. Later, during Paleocene the area was subjected to a compressional deformation phase characterised by SW-directed thrusting and folding, as well as NE-verging backthrusts and backfolds. Our proposed geotectonic model suggests the consumption of the ocean between the Parnassus and Pelagonian microplates. This model includes Late Jurassic eastward ophiolite obduction followed by Early Cretaceous west directed ophiolite thrusting.

► Structural analysis in the Helicon, Gerania and Pelagonian zone in Beotia area.
► Petrofabric analysis in ultramafic rocks, slip system analysis in pyroxenes, olivines and amphiboles.
► Plate tectonic scenario in the Beotia area, central Greece.