THE CARBONATE FLYSCH TRANSITION (LATE MAASTRICHTIAN LATE PALEOCENE) IN THE ARACHOVA SEQUENCE OF THE PARNASSUS-GHIONA ZONE, CENTRAL GREECE

The transition from the carbonate to the flysch facies in the Arachova sequence of the Parnassus-Ghiona Zone is represented by argillaceous limestone beds with flaser structures deposited during latest Maastric htian-Palaeocene time in a pelagic carbonate environment with a period ic elastic influx. Deposition was continuous except for a short interr uption during the K/T boundary interval and the earliest Palaeocene wh en the area was subaerially exposed. This interruption gave rise to th e development of a brecciated carbonate horizon through soil-forming p rocesses. The mineralogical composition of the elastic influx (i.e. qu artz, feldspars, clay minerals, amorphous iron oxides, amorphous phosp hatic compounds), in particular the clay mineral assemblages (i.e. ill ite, chlorite, irregularly interstratified illite-vermiculite), shows that the elastic supply represents erosional material that originated from a tectonically active continental setting of both carbonate and e lastic rocks, presumably the Pelagonian Zone, as for the flysch of the Beotian and Sub-Pelagonian Zones. The arrival of the first elastic ma terial in the Arachova area as early as latest Maastrichtian time, its Pelagonian origin and the persistence of pelagic conditions of sedime ntation throughout the Palaeocene, indicate that the Arachova area was situated along the northeastern margin of the Parnassus platform and that it subsided into the Beotian basin. While the central areas of th e platform remained tectonically stable during middle Palaeocene times and there was an extensive development of stromatolites, the northeas tern marginal areas transitional to the Beotian basin continued to sub side allowing pelagic carbonate sedimentation with periods of elastic influx. The total collapse of the platform in the late Palaeocene gave rise to the deposition of the flysch over the entire zone.