Sedimentation and basin evolution of the Oligocene-Miocene Mesohellenic basin, Greece

The Oligocene-Miocene Mesohellenic basin of northern Greece and southern Albania is filled with up to 4 km of marine turbidites and basin margin strata. Surface outcrops include fa deltas, prodeltaic facies, and sandy and shaly submarine fan facies. All these facies in outcrop can be directly correlated with seismic facies in the subsurface, which in turn are compared with seismic facies in modern sandy submarine fans. Twelve seismic markers provide a stratigraphic framework that has been dated by new nannofossil biostratigraphy. Lowstand facies include erosional channels on the basin slope that aggrade basinward with sandy overbank levees to give composite sand bodies with an overall lobelike character. Distally, these pass into sandy channel-termination depositional lobes. Highstand facies are characterized by shaly basin slopes and shaly turbidites in the basin, with irregular reflections interpreted to represent shallow channels and slumps. The stratigraphic occurrence of lowstand facies compares closely with published eustatic sea level curves. The basin has the potential for significant gas, principally in stratigraphic traps. The Mesohellenic basin developed as a strike-slip half graben, synchronous with the Ionian foreland basin to the west of a mountain belt formed by the Pindos nappes.