An overview of the evolution of the internal hellenides (Albania, Republic of North Macedonia, Greek Central Macedonia): obductions, collisions and North Aegean extension

Abstract

The geological analysis of the Albanian-Macedonian transect constraints a framework of the Internal Hellenides in which 3 or 4 Jurassic oceanic basins opened at 174–160 Ma; they bordered the Western European Continent. During the Late Jurassic, the oceanic crusts subducted eastward, the Mirdita basin below the Pelagonian continent, the Almopias basin below the Malarupa-Veles continent and the Thessaloniki ophiolitic basin below the Continental Margin of the basin. A Paikon Volcanic tholeiitic Island Arc formed above the Almopias subduction and subsequently subducted below the rhyolitic volcanic centre of the Arc; the Guevgueli ophiolitic back-arc basin opened above the subduction of the Paikon Volcanic Arc (164–160 Ma). The top-to-the-W Late Jurassic obduction of the oceanic crusts (D1 event) is followed by a gravitational exhumation (D2 event). A new Mid-Late Cretaceous Almopias marine basin formed; the Late Cretaceous-Palaeocene continental subduction (=collisions, D3-4 events) re-activated the Jurassic subductions and a dacitic Paikon Volcanic Arc formed in the Palaeocene-Early Eocene (56–45 Ma). The Vardar Trough opened at 45 Ma in the back of the dacitic Paikon Volcanic Arc, above the subduction of Vardar and Apulia units; it was submitted in the Late Priabonian to a tectonic event (D5 event, 36–34 Ma) and to the Early Miocene compression (D6 event). The N. Aegean WNW-ESE extension began at ∼21–20 Ma; change from the WNW to the NE-SW/N-S extensional directions occurred between the Tortonian (∼12 Ma) and the Pliocene (∼6 Ma); it was probably driven by hundreds kms of NE-SW/N-S stretching of the Central and Southern Aegean basins.