Western versus Eastern Black Sea tectonic evolution: pre-rift lithospheric controls on basin formation

Abstract

We demonstrate the key role of pre-rift rheology on the kinematics of basin formation in the Western and Eastern Black Sea basins. Constraints on modelling results are provided by a large data-set based on more than 50,000 km of multichannel seismics, offshore and onshore wells, regional gravity and magnetic surveys, refraction seismics and field studies. The model supports the presence of important differences in the thickness and in the thermal state of the lithosphere which rifted to form the Western (middle Barremian) and the Eastern (middle Paleocene) Black Sea subbasins. A 200 km and a 80 km thick pre-rift lithosphere appear to have driven the deformation in the Western and in the Eastern Black Sea, respectively. Differences in the geometry and in the mechanical properties of the pre-rift lithosphere have a strong control on the depth of necking and, thus, on the basin morphology. The model sheds light on palaeotectonic and palaeogeographic reconstructions, duration of rifting events, location of subsiding areas and erosional surfaces. The western and the eastern parts of the Black Sea appear to be two distinct basins, characterised by different evolutionary paths determined by different pre-rift conditions.