REPEATED FRESHWATER DISCHARGE EVENTS CAUSED RAPID SEA-LEVEL CHANGES IN THE BLACK SEA DURING THE HOLOCENE

Fluctuations of Black Sea level during the Holocene coincide with repeated ocean-atmosphere reorganizations (coolings) in the northern hemisphere and changes in the species composition of foraminiferal assemblage (“ecostratigraphic”) zones. We suggest that following the initial invasion of the Black Sea by marine Mediterranean waters during the Pleistocene-Holocene transition, climatic amelioration (warming) following each ocean-atmosphere reorganization resulted in shifting precipitation patterns that produced repeated, rapid freshwater discharges to the Black Sea from surrounding rivers, especially those of the northwest Black Sea shelf. In this scenario, excess runoff following each reorganization temporarily lowered salinity, blocking the entry of Mediterranean immigrants and altering the character of foraminiferal assemblages, as previously noted by Yanko (1990) and Yanko-Hombach (2007). Freshwater discharges to the Black Sea appear to have been insufficient to cause substantial (>~1 m) sea-level fluctuations, based on numerical models. Nevertheless, freshwater discharges may have affected sea-level sufficiently to alter coastal geomorphology and coastal aquifers, causing the translocation of settlements from areas where submarine archaeological sites are now located.