--> --> The Geological Framework of the Offshore Greece (-Hellenides and Hellenic Arc until eastern Crete): a Novel Insight from a New Regional Seismic Survey

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The Geological Framework of the Offshore Greece (-Hellenides and Hellenic Arc until eastern Crete): a Novel Insight from a New Regional Seismic Survey


The geological framework of the Offshore Greece from the Dinarides to the Hellenic Arc is the result of a complex tectonic history. It started by the fragmentation of the Pangea with formation of margins and deep basins by rifting from the Triassic to the Middle Jurassic and spreading in the Upper Jurassic and Lower Cretaceous. The resulting thick Mesozoic basins are still preserved in the Eastern Mediterranean with the Levant Basin and in the offshore Greece, the western Herodotus Basin and the Ionian Basin. As in the whole Tethys realm, a major change occurred in the Upper Cretaceous with the change of motion of Africa relative to Eurasia leading to a compressional regime. Subduction of Africa below Eurasia, creation of back-arc basins and collision resulted in fold and thrust belts.

Another change occurred at the Late Eocene-Early Oligocene (30–35 Ma), when the northward motion of Africa decreased and the subducting slab started to retreat southward with migration of the trench, beginning of the formation of the Mediterranean Ridge accretionary complex and extension in the Aegean region. From the Late Miocene- to- Present, the Anatolian plate was individualized, moving to the West and Southwest in the Aegean area. It is bounded to the North by the North Anatolian strike-slip Fault which crosses the Aegean until the Offshore Greece through the Corinth graben, cutting the Apulian Platform until the Ionian deep basin, along the Keffalonia Fault Zone, where it is bounding westward the Mediterranean Ridge. During this period, the front of the thrust wedge of the Mediterranean Ridge came in contact with the Cyrenaica Promontory. Offshore Greece was also affected in its NE part by the development from the late Miocene to Present, of the Calabrian Arc and its accretionary prism to the SE, linked to the subduction of the Ionian basin. The development of the Mediterranean Ridge and of the Messina Cone resulted in the almost disappearance of the Ionian Mesozoic Basin which, however can extend below these wedges.

The Messinian salinity crisis affected the Offshore Greece with deposition of thick evaporites in the deep basin undisturbed in the remnant Ionian Basin but imbedded in the accretionary prisms which developed during their deposition. Of importance for Exploration is the fact that the whole slope of the Hellenic Arc constituted by a thick stack of thrusts was sub aerially exposed with probable karstification of the carbonates composing the thrusts.

As a result of this complex history, the Offshore Greece along the Hellenic Arc is subdivided into several panels of different structural complexity and water depths. The first regional seismic survey acquired by PGS shed a new light on the Offshore Greece and will allow its hydrocarbon assessment.