Evidence of Pre-Apulian (Paxos) isopic Zone in the Filiatra-Pylos area (SW Peloponnese, Greece)

The studied area, for decades was regarded as belonging to the Gavrovo-Tripolis isopic zone. However, in last years the area has been the subject of extensive geological mapping reinvestigation, which has brought to light the fact that the features of this geographical part could geotectonically be correlated to the Pre-Apulian (Paxos) isopic zone of the external Hellenides.
   The observed lithostratigraphic successions of Filiatra-Pylos area, in comparison with those of Ionian and Gavrovo-Tripolis zones, are clearly and highly distinguishable. In the studied area, the whole Cretaceous to Tertiary sedimentary successions are composed of whitish shallow-water limestones, locally bituminous or rich in organic matter, with multiple emersions bearing scarcely bauxitic episodes, with absence of typical darkish platformal lithofacies like Gavrovo-Tripolis carbonate sequences or any deep-water limestone sequences with chert like Ionian carbonates. In addition to that, the entire examined sedimentary sequence is also developed over a Triassic evaporitic substratum, which is entirely absent within the Plattenkalk Series in Peloponnese. The exceptional thick siliciclastic flysch successions are normally developed over the marly limestones and the clastic deposits and cover by Miocene. Moreover, the flysch sequence in Gavrovo-Tripolis zone and the metaflysch sequence with the Plattenkalk Series are presented by highly restricted outcrops in overall Peloponnese.
   The whole area is also characterised by the presence of large anticlines, however the easternmost flysch sequence outcrops are deformed as thrust and fold structures, by the SW advancing propagation of the Hellenides. The dominant mesoscale structures are those of faulted anticlinal folds, which have roughly northwest-southeast-trending fold axes and overturn to the southwest. These structures are due to the overthrust caused by Mesozoic-Tertiary pelagic sequence of Pindos thrust belt and by conglomerate debris-flow mega-slivers. These slivers are originating from the deeply up-faulted, gravity sliding and collapse of the upper levels of the Gavrovo-Tripolis and Pindos thrust belts.
   Gavrovo-Tripolis and Apulian platforms formed during Early Mesozoic Tethyan opening and they developed as a part of the Early Cretaceous foreland-thrust belt system, which resulted from the collision of Apulia and Eurasia. During the Tertiary, the Apulian continental margin was affected by compressional tectonics due to the continuing collision. Subduction of Apulia beneath the Hellenic margin of the upper European Plate took place in the Miocene, which is responsible for the tectonic deformation due to the increasing west-toeast lithospheric shortening and gives rise to the intracontinental subduction formation of Plattenkalk and Phyllite-Quartzite Series.
   Consequently, the examined sedimentary features, in Filiatra-Pylos area, are well correlated with the lithostratigraphic successions of Paxos, Ithaki, Cephalonia, Lefkas and Zakynthos, but are also connected with those of Megisti Island in Dodecanese, which geotectonically belongs to the Pre-Apulian isopic zone of the External Hellenides.