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

Abstract

We demonstrate the key role of pre-rifl 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.

Heterogeneous structure of the lithosphere in the Black Sea from a multidisciplinary analysis of geophysical fields

“…40 Ma years to Coniacian. Constraints from seismic reflection data suggest that rifting phase in the WBSB occurred over up to 30 Ma after beginning in the Middle Barremian [Spadini et al, 1996]. These durations are also consistent with modeling thermal history of rifting event (ca.…”

“…This inference does not contradict the model involving rifting of thermally and mechanically different lithosphere beneath the Black Sea subbasins [Spadini et al, 1996]. Seismic tomography revealed different structure velocity of the lithosphere up to 150 km depth in the EBSB and WBSB [Bugaenko et al, 2008;Yegorova, Gobarenko, 2010;Yegorova et al, 2013].…”

“…Despite abundant consideration that the Black Sea is a back-arc basin, there are still strong debates about the details of its origin and evolution [e.g. Zonenshain, Le Pichon, 1986;Finetti et al, 1988;Okay et al, 1994;Spadini et al, 1996;Cloetingh et al, 2003;Nikishin et al, 2003;Kutas, 2003;Besutiu, Zugravescu, 2004;Afanasenkov et al, 2007;Hippolyte et al, 2010;Çinku et al, 2013;Kaymakci et al, 2014;Nikishin et al, 2015a, b]. The key differences among the models for kinematics history of the region address the timing for opening of the Black Sea and the determining of the location, number, size and kinematics of original Neotethyan fragments related to the tectonic development of the region.…”

“…Thermo-mechanical and gravity modeling, seismic tomography have revealed the different lithospheric structure as a whole in the Western and Eastern Black Sea Basins without addressing separate and distinct tectonic elements of the crust [Spadini et al, 1996;Cloetingh et al, 2003;Bugaenko et al, 2008;Nikishin et al, 2011;Yegorova et al, , 2013. The available information is however insufficient to determine comprehensively the relationship between the geological units in the crust and upper mantle that governs substantially the tectonic setting and evolution of the basins.…”

“…They were made during 55 years by various industrial and academic organizations from the Former Soviet Union including the Institute of Geophysics of the National Academy of Sciences of Ukraine [Starostenko et al, 2004a]. The map is much more detailed and informative than those of published earlier [Belousov et al, 1988;Spadini et al, 1996;Starostenko et al, 2004a;Sandwell, Smith, 2009;Yegorova, Gobarenko, 2010].…”