Palynological evidence for climatic change, anthropogenic activity and outflow of Black Sea water during the late Pleistocene and Holocene: Centennial- to decadal-scale records from the Black and Marmara Seas

Abstract

Previous marine palynology studies of pollen and dinoflagellate cysts (dinocysts) in the Black Sea–Mediterranean corridor were made on short cores, allowing only millennial-century scale reconstruction of past climates. We now describe pollen accumulation rates for 5 cores with eleven 14C ages over 30,000 years, and new decadal-scale data for a Holocene core with fourteen 14C ages. Pollen influxes show Pinus–Abies–Quercus forest-steppe and deteriorating climate from 29.8–24kyrBP, then colder, drier pre- and post-LGM conditions, with Artemisia, Cheno-Ams and Ephedra that lasted through the Bølling interstade. Deciduous oak returns by the Younger Dryas, and rapidly expands, followed by Pistacia by 9.3kyrBP. Foraminiferal δ18O shows 4°C cooler than present late glacial summers and rapid Holocene warming. By 9BP, influxes from Quercus cerris, Tilia, Fagus, Castanea, Ulmus, shade ferns, aquatics, swamp plants and δ18O indicate warm winters (5°C or more) and year-round precipitation (>600–1000mm), not the dry conditions that would be required for Black Sea drawdown. There is mid-Holocene expansion of Carpinus, evergreen Quercus and Pistacia. Walnut, olive and cereal pollen suggest early cultivation attempts, but no sustained farming before 4.5kyrBP.Dinocyst assemblages show major changes traceable throughout the Corridor. Variability in process length marks low diversity (N=13) Pleniglacial–early Holocene Spiniferites cruciformis assemblages, suggesting fluctuating salinity like the modern Caspian Sea, with brackish to saline conditions (∼5–16‰). Distributions of euryhaline cysts Spiniferites mirabilis and Spiniferites bentorii show the Aegean and Marmara Seas were connected by ∼11kyrBP and linked to Black Sea by 9.3kyrBP. There is no palynological evidence of either freshwater (salinity<3‰) for farming on the southwest shelf or of catastrophic marine flooding.