Is the impact of the Messinian Salinity Crisis in the Black Sea comparable to that of the Mediterranean?

Erosional features have been observed along the Black Sea shelf in wells and on seismic reflection profiles that are broadly similar to the seismic stratigraphic signature of the Messinian Salinity Crisis (MSC) in the Mediterranean. In particular, the intra- (or Middle) Pontian unconformity has been suggested by some as the manifestation of the MSC in the Black Sea Basin. Missing strata and prominent lithological changes associated with the inferred MSC unconformity indicate erosional removal of parts of the underlying Cenozoic deposits in the shelf areas of the entire Black Sea. The magnitude of the relative sea level drop associated with this unconformity has been much debated, and ranges from tens of meters to thousands of meters. The suggestion of a very large (1600 m!) sea level drop in the Black Sea during the MSC is primarily based on the findings of shallow-water clastics and carbonates in Deep Sea Drilling Project (DSDP) wells 380 and 381. However, recently acquired long-offset seismic data clearly show that both of these wells penetrated gravity-driven mega-slumps and mass transport complexes. Therefore the interpreted shallow water MSC units in these deepwater wells do not represent in situ rock formations, but rather allochthonous strata derived from the basin margin. Moreover, compared to the typical seismic expression of the MSC in the Mediterranean, detailed interpretation of 2D/3D seismic data sets in the Bulgarian and Turkish Black Sea revealed considerably more complexity. This marked difference is tentatively attributed to the extent of erosion associated with the MSC in the Black Sea, i.e. the multiple MSC incisions occurred in a submarine setting, not on a subaerially exposed palaeoslope. Therefore the magnitude of the sea level drop and the overall impact of the MSC in the Black Sea appear to be significantly less than in the Mediterranean. •In the Black Sea, the MSC signature is critically dependent on the DSDP 380 and 381 wells.•The “pebbly breccia” has been incorrectly interpreted as a fluvial/tidal deposit.•The “pebbly breccia” is the basal part of a large mass transport complex.•The MSC sea-level drop should have been much less than 1600 m.•The footprint of the MSC is less dramatic in the Black Sea than in the Mediterranean.