A kinematic modelling approach to lithosphere deformation and basin formation: application to the Black Sea

Abstract

AbstractA kinematic model of lithosphere deformation has been developed that integrates the following components: structural deformation of the crust and mantle lithosphere; thermal conditioning, perturbation and subsequent re-equilibration of the lithosphere temperature field; flexural isostatic adjustments; and surface processes, including both lateral and temporal variations in basin fill and bathymetry. This approach enables the forward modelling of extensional basin evolution in two and three dimensions followed by deformation due to subsequent extensional and compressional (i.e. inversion) events.The model has been applied to the Black Sea, which is one of the deepest basins in the world and yet it is poorly understood in terms of the mechanisms that have controlled its evolution. Although it is widely accepted that this basin was initiated by Mesozoic back-arc extension related to the subduction of the Tethys Plate to the south, most of the subsidence observed today occurred within the Palaeogene and Neogene (i.e. within the framework of the Alpine–Himalayan orogenic belt). The modelling approach described above has been used to test possible geological and geodynamic mechanisms that have controlled the subsidence history of the Black Sea. In particular, the investigation has focused on trying to explain the anomalously thick post-rift subsidence that occurred in the basin. Models assuming uniform lithosphere extension do not generate the observed thickness of sediment infill in the basin. Similarly, modelling of the compressional deformation around the edges of the basin structure does little to explain the large magnitude of subsidence within the centre of the basin. Model results show that the observed basin depths can be attained only when the total magnitude of deformation is constrained from crustal thickness changes rather than by fault displacement measurements.