The margin of the northeastern Black Sea is formed by the Crimea and Kerch peninsulas separating it from the Azov Sea to the north. The age and architecture of the sedimentary successions in this area are described from exploration reflection seismic profiling acquired in the area as well as the "one-off" regional DOBRE-2 CDP profile acquired in 2007. The sediments range in age from Mesozoic to Quaternary and can be divided into five "seismostratigraphic" complexes linked to the tectono-sedimentological evolution of the area. The present regional basin architecture consists of a series of basement structural highs separating a series of sedimentary depocentres and is mainly a consequence of the compressional tectonic regime affecting the area since the Eocene and which has focused shortening deformation and uplift along the axis of the Crimea-Caucasus inversion zone on the Kerch Peninsula and Kerch Shelf of the Black Sea. Two major sedimentary basins that mainly formed during this timethe Sorokin Trough in the Black Sea and the Indolo-Kuban Trough to the north of the Kerch Peninsula in the Azov Sea-formed as marginal troughs to the main inversion zone.

The tectonic evolution of the Eastern Black Sea Basin has previously been explained based on offshore and onshore data, some of the latter from the Crimean Mountains (CM). However, changes in the stratigraphy of the CM have recently been proposed: the Late Triassic–Early Jurassic Tauric Group was assigned as younger (Albian). To clarify the stratigraphy and the tectonic evolution of this area, we sampled the eastern CM for micropalaeontological datings (nannoplankton). The results demonstrate an Early Cretaceous age for the Tauric Group in the eastern CM. The samples contained substantial amounts of volcanic ash, indicating a period of magmatic activity along all the eastern CM. Our field observations allowed us to propose a new structural map and cross-sections, using which three main tectonic units were distinguished. We define a phase of extension during the Early Cretaceous and one of shortening during the Paleocene–Early Eocene, before the main Middle Eocene limestone unconformity. These two phases are related to: (1) the opening of the Eastern Black Sea Basin along NNW–SSE-trending normal faults and the associated magmatism; and (2) north–south shortening that could be comparable with the inversion in Dobrogea and/or with north–south shortening linked to the collision of continental blocks in the Pontides and Taurides domains.

The southern part of the Eastern European continental landmass consists mainly of a thick platform of Vendian and younger sediments overlying Precambrian basement, referred to as the East European and Scythian platforms (EEP and SP). Some specific geological features, such as the Late Devonian Pripyat-Dniepr-Donets rift basin, the Karpinsky Swell, the Permo(?)-Triassic troughs of the SP, and the deformed belt running from Dobrogea to Crimea and the Greater Caucasus, in which rocks as old as Palaeozoic crop out, form a record of the geodynamic processes affecting this part of the European lithosphere. Hard constraints on the Palaeozoic history of the SP are very sparse. The conventional view has been that the SP is a Late Palaeozoic orogenic belt. However, it is shown that the few available data are also consistent with an alternative interpretation in which it is the thinned margin of the Precambrian continent, reworked by Late Palaeozoic-Early Mesozoic rifting events. The geodynamic setting of the margin is classically reported as one of active convergence throughout the Late Palaeozoic and Early Mesozoic, with subduction of the Palaeotethys Ocean beneath Europe. Actually, there are no direct observations constraining the polarity of Palaeotethys subduction in this area although indirect evidence is not inconsistent with the conventional model. In such a case, the sedimentary-tectonic record of the SP suggests that convergence during the Permo-Triassic(?) and certainly during the Early and Mid-Jurassic was oblique. An Eo-Cimmerian (Late Triassic-Early Jurassic) event is widespread and implies a tectonic compressional regime with systematic inversion of most sedimentary basins. There is also a widespread unconformity at the end of the Mid-Jurassic and in the Late Jurassic. These can be interpreted as indicators of compressional tectonics; however, nowhere is there evidence of intense shortening or other orogenic processes. A revised tectonic model is proposed for the area but, given the degree of uncertainty characterizing the geology of this area, it is best considered as a basis for further discussion.

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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)