Lithospheric structural control on inversion of the southern margin of the Black Sea Basin, Central Pontides, Turkey

To illustrate the structural evolution of the Black Sea Basin in the context of Neotethyan subduction and subsequent continental collisions, we present the first lithosphere-scale, similar to 250-km-long, balanced and restored cross section across its southern continental margin, the Central Pontides. Cross-section construction and restoration are based on field, seismic-reflection, geophysical, and apatite fission-track data. The structure of the onshore Pontides belt is predominantly controlled by inverted normal faults, whereas the offshore areas are devoid of large structural inversion. The restored section indicates that Cretaceous crustal thinning occurred synchronously with ( probably buoyancy-driven) exhumation of a forearc high-pressure blueschist wedge likely during Neotethyan slab retreat. Apatite fission-track data show that structural inversion of the forearc zone, which formed the Central Pontides fold-and-thrust belt, started at ca. 55 Ma. This Eocene structural inversion followed upon collision of the Kirsehir continental block and the arrest of Neotethyan oceanic subduction below the Central Pontides. Compared to the Central Pontides belt, which underwent significant shortening (similar to 28 km, i. e., similar to 33%), the relatively colder and stronger Black Sea lithosphere prevented the northern offshore areas from undergoing inversion. We propose that the location of Cenozoic contractional deformation is related to the absence of lithospheric mantle below the southern Pontides ( forearc) zone as a consequence of the Cretaceous high-pressure wedge exhumation.