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International audience; The geodynamic evolution of the Black Sea Basin can be unravelled by structural and kinematic analyses along its inverted margins. In the frame of the Darius Programme we acquired structural data in the Pontides and in the Crimean Mountains. In the Western Pontides intense extensional faulting occurred during the Early Cretaceous and controlled the deposition of the siliciclastic sediments dated as Hauterivian to Albian (Hippolyte et al., 2010). Development of horst and graben structures resulted in the gravitational sliding of limestone olistoliths. The early Cretaceous fault blocks are unconformably overlain by a Late Cretaceous sequence that generally begins with Coniacian red pelagic limestones.Similar to the Western Pontides, in the Central Pontides intense extensional deformation took place during the Early Cretaceous when sedimentation was characterized by olistoliths and debris flows. Tectonic subsidence locally reached 3600 m. During the Cenozoic, inversion of normal faults created a doubly vergent orogenic wedge (Espurt et al., 2014).On the conjugate margin of the Black Sea, we mapped an array of collinear normal faults in the western part of the Crimean Mountains (Hippolyte et al, 2018). These faults trend parallel to the crustal-scale structures of the Black Sea Basin. Similar to the Pontides, extensional block faulting occurred during the deposition of debris flow and olistoliths, and the extension direction was NE-SW. The syn-rift sequence is dated as Valanginian-Late Albian. The post-rift sequence, that unconformably overlies the graben structures, starts in the Cenomanian. It is devoid of any normal faults or olistoliths. In the eastern Pontides we studied the onshore extension of the transfer faults of the eastern Black Sea Basin. From the Early Campanian to the Late Paleocene they only move with normal slip, possibly related to thermal subsidence in the Black Sea Basin (Hippolyte et al., 2017). Therefore, their strike-slip displacement, related to the opening of the Eastern Black Sea Basin, must predate the Campanian.Given the fact that extensional structures are presents on the two conjugate margins of the Black Sea, and that the directions of extension are normal to the crustal structures (mid-Black Sea High and Black Sea margins), we infer that the Early Cretaceous extension is related to the rifting phase of the Black Sea Basin. We conclude that rifting occurred from the Valanginian to the Late Albian. The age of the breakup unconformity in Crimea, and the Late Cretaceous evolution of the transfer faults, suggest a drifting period from the Cenomanian to the Santonian, a period of intense volcanic activity and weak extensional deformation along the southern margin of the Black Sea. Based on the directions of rifting we propose that the Black Sea Basin opened with rotations accommodated by transform faults at its western and eastern margins, as a consequence of two asymmetric rollbacks of the northward subducted Neo-Tethyan slab. The inversion of the Black Sea margins results from several shortening events related to the continental collisions that occurred to the south. We characterize these events by distinct compressional stress fields from the Eocene to the Quaternary.

International audience; We compared the stratigraphic formations along the southern margin of the Black Sea using 196 nannoplankton ages determined in the Western and Central Pontides, and 112 new samples from the Eastern Pontides. We inferred that the İstanbul and Sakarya zones were amalgamated prior to the Early Cretaceous. Extensional subsidence migrated eastwards along the Pontides from the Barremian to the Palaeocene. An eastwards younging of the Cretaceous magmatism suggested that the eastern Black Sea Basin is younger. Locally, angular unconformities and a stratigraphic gap testify to the Late Albian uplift of the Central Pontides, as the consequence of the collision of an oceanic edifice. Cretaceous Oceanic Red Beds are marker beds of Santonian age along the much of the Pontides, and are of mainly Campanian age within the Eastern Pontides. The Middle-Campanian-Paleocene was a non-volcanic period characterized by extensional subsidence mainly along the eastern Black Sea Basin. The end of Cretaceous volcanism can be correlated with a southwards subduction jump. Syn-compressional basins show that contraction started during the Ypresian along the entire Pontide belt. Eocene volcanism started earlier in the north (Lutetian) than in the south (Bartonian) of the Eastern Pontides. This propagation of syn-collisional volcanism could have resulted from slab steepening under the Eastern Pontides.

International audience; Geophysical data allowed the construction of a ~250-km-long lithospheric-scale balanced cross section of the southern Black Sea margin (Espurt et al. 2014). In this paper we combine structural field data, stratigraphic data, and fault kinematics analyses with the 70 km-long onshore part of the section to reconstruct the geodynamic evolution of the Central Pontide orogen. These data reveal new aspects of the structural evolution of the Pontides since the Early Cretaceous. The Central Pontides is a doubly vergent orogenic wedge that results from the inversion of normal faults. Extensional subsidence occurred with an ENE-trend from Aptian to Paleocene in a forearc setting. We infer that the Black Sea back-arc basin also opened during this period, which was also the period of subduction of the Tethys Ocean below the Pontides. As in the Western Pontides, the Cretaceous-Paleocene subsidence was interrupted from Latest Albian to Coniacian time by uplift and erosion that was probably related to a block collision and accretion in the subduction zone. The restoration of the section to its pre-shortening state (Paleocene) shows that fault-related subsidence locally reached 3600 m within the forearc basin. Structural inversion occurred from Early Eocene to Mid-Miocene as a result of collision and indentation of the Pontides by the Kırşehir continental block to the south, with 27.5 km (~28%) shortening along the section studied. The inversion was characterized by NNE-trending shortening that predated the Late Neogene dextral escape of Anatolia along the North Anatolian Fault and the modern stress field characterized by NW-trending compression within the Eocene Boyabat basin.

International audience; The Eocene uplift and inversion of a part of the Black Sea margin in the Central Pontides, allows to study the stratigraphic sequence of the Western Black Sea Basin. The revision of this sequence, with 164 nannoplankton ages, indicates that subsidence and rifting started in the Upper Barremian and accelerated during the Aptian. The rifting of the Western Black Sea Basin lasted about 40 Myr (from late Barremian to Coniacian). In the inner, inverted, Black Sea margin, the syn-rift sequence ends up with shallow marine sands. The uppermost Albian to Turonian was a period of erosion or non deposition. This regional mid-Cretaceous stratigraphical gap might result from rift flank uplift, as expected in the case of a thick and cold pre-rift lithosphere. However, coeval collision of the Kargi Block, along the North Tethyan subduction zone at the southern margin of the Pontides, might also have contributed to this uplift. A rapid thermal post-rift subsidence of the margin occurred during the Coniacian-Santonian. Collision of the Kirşehir continental block commenced in Early Eocene time (zone NP12) giving rise to compressional deformation and sedimentation in piggyback basins in the Central Pontides, whereas the eastern Black Sea was still opening.

Ce travail concerne la partie est de la chaine des Pontides et en fait une description géologique, stratigraphique, tectonique., pas de résumé

Etude géologique de cette région des Pontides., pas de résumé