International audienceWe 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 subducting northward below the continental Eurasia plate. Based on the analysis of the obducted ophiolites that 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 subduction with the Neotethys plate. We argue that the subduction of the spreading center opened a slab window that allowed asthenospheric material 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 obducted onto the Taurides–Anatolides–South Armenia Microplate (TASAM), which then collided with Eurasia along a single suture zone (AESA suture)

The tectonic and geological evolution of Georgia and the Caucasus, on the whole, are largely determined by its position between the still converging Eurasian and Africa–Arabian lithosphere plates, within the wide zone of a continent–continent collision. The region in the Late Proterozoic–Early Cenozoic belonged to the now-vanished Tethys Ocean and its northern (Eurasian) and southern (Africa–Arabian) margins. Within this convergence zone there existed a system of island arcs, intra-arc rifts, back-arc basins characteristic of the pre-collisional stage. During syncollisional (the Oligocene–Middle Miocene) and post-collisional (the Late Miocene–Quaternary) stages, at the place of back-arc basins were formed fold and thrust belts of the Greater and Lesser Caucasus separated by the Transcaucasian intermontane lowland. Starting from the Late Miocene and as far as the end of the Pleistocene, in the central part of the region, simultaneously with formation of molassic basins and accumulation of coarse molasses there took place volcanic eruptions in subaerial conditions. According to the numerous data obtained during past decades we present a review on the lithological and structural characteristics of these collisional basins and on the coeval magmatic events.

The Kura foreland fold–thrust belt is located in the northern part of the active collisional Lesser Caucasus orogenic belt associated with Arabia–Eurasia convergence. This belt is the best example of mountain-building processes in late Alpine time. Seismic reflection profiles show that the Kura foreland fold–thrust belt of the eastern Caucasus is an active thin-skinned fold–thrust belt and is represented by fault-bend folds, fault-propagation folds and duplexes. Analysis of growth strata in seismic profiles and oil well data from the Kura foreland fold–thrust belt documents that the evolution of deformation has been continuing during the last c. 14–15 myr (since the Middle Miocene), together with the thrust system kinematics. The geometry of the growth strata is associated with footwall synclines and piggy-back basins. Compressional deformation on the Kura foreland began in the Middle Miocene (Chokrakian) and reached its maximum rate at the end of the Miocene (c. 5 Ma).

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