Abstract
Abstract. High-resolution pollen and dinoflagellate cyst records from sediment core M72/5-25-GC1 were used to reconstruct vegetation dynamics in northern Anatolia and surface conditions of the Black Sea between 64 and 20 ka BP. During this period, the dominance of Artemisia in the pollen record indicates a steppe landscape and arid climate conditions. However, the concomitant presence of temperate arboreal pollen suggests the existence of glacial refugia in northern Anatolia. Long-term glacial vegetation dynamics reveal two major arid phases ~64–55 and 40–32 ka BP, and two major humid phases ~54–45 and 28–20 ka BP, correlating with higher and lower summer insolation, respectively. Dansgaard–Oeschger (D–O) cycles are clearly indicated by the 25-GC1 pollen record. Greenland interstadials are characterized by a marked increase in temperate tree pollen, indicating a spread of forests due to warm/wet conditions in northern Anatolia, whereas Greenland stadials reveal cold and arid conditions as indicated by spread of xerophytic biomes. There is evidence for a phase lag of ~500 to 1500 yr between initial warming and forest expansion, possibly due to successive changes in atmospheric circulation in the North Atlantic sector. The dominance of Pyxidinopsis psilata and Spiniferites cruciformis in the dinocyst record indicates brackish Black Sea conditions during the entire glacial period. The decrease of marine indicators (marine dinocysts, acritarchs) 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. This freshening is possibly related to humid phases in the region, to connection between Caspian Sea and Black Sea, to seasonal freshening by floating ice, and/or to closer position of river mouths due to low sea level. In the southern Black Sea, Greenland interstadials are clearly indicated by high dinocyst concentrations and calcium carbonate content, as a result of an increase in primary productivity. Heinrich events show a similar impact on the environment in the northern Anatolia/Black Sea region as Greenland stadials.
Highlights
The climatic conditions during the marine isotope stage 3 (MIS 3) are characterized by abrupt alternations of cold and warm intervals, known as Dansgaard–Oeschger (D–O) cycles or Greenland stadials (GS) and Greenland interstadials (GI), respectively (Dansgaard et al, 1993; Grootes et al, 1993; Svensson et al, 2006)
The last glacial pollen and algal records from Black Sea core 25-GC1 clearly reveal that the climate in the Black Sea/northern Anatolian region is strongly influenced by orbital, millennial- and multi-centennial-scale climate variability
The concomitant presence of temperate and warm-temperate arboreal pollen suggests the existence of glacial refugia in northern Anatolia
Summary
The climatic conditions during the marine isotope stage 3 (MIS 3) are characterized by abrupt alternations of cold and warm intervals, known as Dansgaard–Oeschger (D–O) cycles or Greenland stadials (GS) and Greenland interstadials (GI), respectively (Dansgaard et al, 1993; Grootes et al, 1993; Svensson et al, 2006). High-resolution pollen records from Greece mainland (Tzedakis et al, 2004; Müller et al, 2011) and the Aegean Sea island Lesbos (Margari et al, 2009), reveal a high sensitivity and rapid responses of vegetation to D–O cycles, whereas records from the Caucasus (Arslanov et al, 2007) and the Cretan basins (Geraga et al, 2005) do not show a clear D–O-like pattern These contradictory pollen data highlight the necessity for more high-resolution pollen studies in the eastern Mediterranean region, as pointed out by Fletcher et al (2010)
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