TECTONOSEDIMENTARY SIGNIFICANCE OF THE MESSINIA CONGLOMERATES (SW PELOPONNESE, GREECE)
The marine fill of the Gavrovo-Tripolis foreland basin in the Messinia area (SW Peloponnese), includes facies and facies associations, deposited by sediment gravity flows in slope and inner fan settings. The above-mentioned gravity-driven sedimentary processes, resulted in the formation of thinning-upward sequences and fining fan facies associations, composed of impressive sheet-conglomerates at the base (Agia Mavra, Agia Varvara and Mali units), presenting mainly normal internal structure, while clay and sand-clay members predominate at the top. These conglomerates advocate a significant sediment supply and extended accommodation space, during periods of dramatic tectonic uplift, associated with the westward propagation of Pindos thrust front. In the prograding fan system, dominate paleo-currents with main flow direction to southwest. The finer fan facies associations show rapid lateral variations, both in lithology and thickness, indicating rapid changes in the inner, incised, part of the foredeep. Nannofossil analyses suggest that the sedimentation took place during Oligocene (NP22 to NP24 biozones). Three NNW-SSE trending thrust fault zones bound the above-mentioned units and they caused an important structural thickening of the fan facies associations. Biostratigraphic analyses date the end of the thrust activity in GavrovoTripolis zone in Late Oligocene (biozone NP24).