Petrostratigraphic evolution of the Thrace Basin (Bulgaria, Greece, Turkey) within the context of Eocene-Oligocene post-collisional evolution of the Vardar-İzmir-Ankara suture zone

Eocene-Oligocene paleogeographic/paleotectonic reconstructions of the Rhodopian – northern Aegean – western Black Sea region largely ignore the Thrace Basin, a large sedimentary basin up to 9 km thick that has been long interpreted as a forearc basin developed in a context of northward subduction. Recent structural, stratigraphic, petrologic, and sedimentologic data challenge this notion and may instead be interpreted within a context of upper-plate extension during the complex transition between the collisional tectonic regime related to the closure of Vardar-Izmir-Ankara oceanic realm and the extensional regime characterizing the Oligocene-Neogene evolution of the Aegean and peri-Aegean regions. The detritus filling the Thrace Basin was derived from two main sediment source areas: (i) the mostly metamorphic terrains of the Rhodopes to the west and (ii) the Vardar-Izmir-Ankara and Biga (intra-Pontide?) subduction-accretion prisms to the southwest. During most of the Eocene-Oligocene, the entire basin was...