PLEISTOCENE-HOLOCENE (MIS 5-1) CLIMATIC CHANGES IN SW BLACK SEA: PALYNOLOGY OF DSDP SITE 380

Site 380 of the Deep Sea Drilling Program [DSDP] is located in the southwestern region of the Black Sea (42°05.94’, 29°36.82’E; 2115m water depth). The location of this site is important due to its proximity to the narrow Bosphorus strait, the only present-day connection between the Black Sea and the Aegean Sea. Major drops in eustatic sea level during extensive late Pleistocene glacial episodes following MIS 5 disconnected the Black Sea from the Aegean Sea at the Bosphorus strait. The water levels created changes from low salinity marine to brackish or freshwater within the Black Sea during these intervals. Organic-walled phytoplankton (dinoflagellate cysts, acritarchs, and fresh-water algae) were investigated to better constrain these glacio-eustatic sea-level changes associated with extensive Pleistocene glacial episodes that resulted in interruption of water exchange between the Black Sea and the Aegean Sea. A combination of high-precision analysis of morphological changes seen in two of the most abundant dinoflagellate cyst species present, Galeacysta etrusca and Spiniferites cruciformis, was undertaken and combined with dinoflagellate assemblage changes to evaluate a possible morphological response of the cysts to changes in sea-surface salinity and better quantify the impact of sea level changes on the history of the connection. New data on modern salinity associations of S. cruciformis and Pterocysta cruciformis in the Black Sea corridor indicate surface water salinities ranging mainly between about 2 and 13 (rarely up to 18) psu.