Orbital and millennial-scale environmental changes between 64 and 25 ka BP recorded in Black Sea sediments.

High-resolution pollen and dinoflagellate cyst records from marine sediment core 25-GC1 were used to reconstruct vegetation dynamics in Northern Anatolia and surface conditions of the Black Sea between 64 and 25 ka BP. During this period, the dominance of Artemisia in the pollen record indicates a steppe landscape and arid climate conditions. However, the presence of temperate and warm-temperate arboreal pollen suggests the existence of glacial refugia in Northern Anatolia. A general cooling trend towards 25 ka BP is evidenced by the decrease of Quercus and increase of Pinus. There is evidence of orbital-driven vegetation dynamics in Northern Anatolia during 64-25 ka BP with spread of steppe during precession minima (insolation maxima) and development of forests during precession maxima (insolation minima). Dansgaard-Oeschger (D-O) events are characterized by a marked increase in temperate tree pollen, indicating a spread of forests due to warm and wet conditions in Northern Anatolia. The dominance of Pyxidinopsis psilata and Spiniferites cruciformis in the dinocyst record indicates a rather brackish Black Sea during the last glacial period. The decrease of marine indicators (marine dinocysts, acritachs) at ~ 54 ka BP and increase of freshwater algae (Pediastrum, Botryococcus) from 32 to 25 ka BP reveals freshening of the Black Sea surface water, related to orbital-driven arid/humid phases in the region, influencing hydrology and level changes of the Black Sea. D-O interstadials are characterized by high dinocyst concentrations and calcium carbonate content, as a result of an increase in primary productivity in the Black Sea. Heinrich events show a similar impact on the environment in Northern Anatolia/Black Sea region as D-O stadials. [ABSTRACT FROM AUTHOR]