The black Sea back-arc basin: Insights to its origin from geodynamic models of modern analogues

The Black Sea is generally thought to be a back-arc basin with active extension (rifting) beginning in late Early Cretaceous times - although some fundamental issues such as the presence or absence of a related magmatic arc and the orientation of the related, driving, subduction zone remain vaguely defined at best. However, as shown here, the regional structure of the Black Sea is consistent with that predicted by geodynamic models of modern back-arc basin formation, in which extension is driven by slab roll-back. This includes an asymmetric distribution of horst and graben structures in the back-arc basin, the distribution and spacing of which is related to the strength of the underlying lithosphere, which forms the hanging wall of the subduction zone. By analogy, the intrabasinal structure of the Black Sea as a whole is explicable as the consequence of a single phase of asymmetric back-arc basin formation, not two separate phases independently responsible for its western and eastern segments, and its underlying lithosphere is rheologically strong, as predicted by recent models of Precambrian Europe and present-day tomography.