Molasse Formations in the Hellenides

Abstract

The paleo-geodynamic areas of deposition of the synorogenic formations of flysch, flysch-molasse and molasse within the orogenic arc of the Hellenides are described. The Rhodope – North Aegean molasse was deposited unconformably on the metamorphic rocks of Rhodope. Its basal sediments are of Lower – Middle Eocene age and the sedimentary sequences reach up to the Oligocene/Miocene boundary. The Mesohellenic basin has been regarded as a back arc molassic basin of the Hellenides during Oligocene – Middle Miocene. The Early Miocene Cycladic molasse is characterized by folds and thrusts, as well as cataclasites at its base, along extensional detachments, above the metamorphic core complex of the Cyclades. The Late Oligocene – Early Miocene molasse of the Epirus – Acarnania syncline in western Greece lies on top of a large N-S syncline of flysch covering both the Ionian and Gavrovo units. The molasse of the Cretan Basin represents the actual back-arc basin, whose rifting begun during the Middle Miocene. Its sedimentary thickness reaches 1.5–2 km, while its depth ranges from 1.5–2 km and thus, a total subsidence of at least 3–4 km is estimated. Its crustal thickness is only 16-18 km and thus, it is underlain by thinned continental crust. The Oligocene-Early Miocene Giona flysch-molasse has been folded and ruptured by high-angle strike-slip faults. The Early - Middle Miocene Itea – Amfissa supra-detachment molasse basin was created on the hanging wall of the Eastern Giona extensional detachment, overlain by extensional nappes of Mesozoic limestones.