The eastern Black Sea-Caucasus region during the Cretaceous: New evidence to constrain its tectonic evolution

Abstract We report new observations in the eastern Black Sea-Caucasus region that allow reconstructing the evolution of the Neotethys in the Cretaceous. At that time, the Neotethys oceanic plate was subductingnorthward below the continental Eurasia plate. Based on the analysis of the obducted ophiolitesthat crop out throughout Lesser Caucasus and East Anatolides, we show that a spreading center (AESA basin) existed within the Neotethys, between Middle Jurassic and Early Cretaceous. Later, the spreading center was carried into the subductionwith the Neotethys plate. We argue that the subductionof the spreading center opened a slab windowthat allowed asthenosphericmaterial to move upward, in effect thermally and mechanically weakening the otherwise strong Eurasia upper plate. The local weakness zone favored the opening of the Black Sea back-arc basins. Later, in the Late Cretaceous, the AESA basin obductedonto the Taurides–Anatolides–South Armenia Microplate (TASAM), which then collided with Eurasia along a single suture zone (AESA suture).