A post Younger Dryas Black Sea regression identified from sequence stratigraphy correlated to core analysis and dating

摘要

The north-western Black Sea shelf is the widest continental shelf of the Black Sea, where the Danube delta/prodelta system includes important records on the Black Sea water level fluctuations. This study integrates newly acquired high-resolution single channel seismic reflection profiles and Calypso piston cores recovered along a transect extending from the Danube delta deep into its deep sea fan. The correlated results provide information on the Late Quaternary architecture of the Danube Black Sea shelf and on the role of global glacio-eustatic fluctuations on the building of the Danube delta/prodelta. The sedimentary sequences in the Black Sea are strongly affected by water level changes. For the whole duration of Late Glacial-Holocene period, the level of the Black Sea was controlled by the regional climate modifications rather than the global eustatic changes. The seismic sequences recognized on a very high-resolution seismic profile were dated by two Calypso piston cores. Based on the obtained data, during the Last Glacial Maximum the Black Sea was a land locked lake with the level below -120 m. In the course of the deglaciation the lake level rose up to -40 m, which is confirmed by occurrence of the prodelta lobes formed after the rise in water level originated from the melt water. Following the Younger Dryas, 11 000-8500 ~(14)C BP, there occurred a new level lowering to the level of -100 m, identified by the forced regression deposits recorded on the Romanian shelf. This last lowstand previously recognized by a pronounced shoreline with a characteristic beach profile and a belt of coastal dunes is also indicated by the prodelta at -100 m depth. All these coastal features as well as the incised anastomosed channel system remained preserved on the shelf resulting from a rapid ultimate transgression starting immediately after 8500 ~(14)C BP.