Vegetation, climate and environmental dynamics of the Black Sea/Northern Anatolian region during the last 134 ka obtained from palynological analysis

Abstract

As a part of the multidisciplinary project “Dynamics of Mid-latitude/Mediterranean climate in Northern Anatolia/Black Sea region during the last 150 kyr”, this research presents new pollen and organic-walled dinoflagellate cyst records from the SE Black Sea for the penultimate deglaciation – Eemian (134-119 ka), last glacial (64-23 ka) and last deglaciation – Holocene (18 ka – present) periods. The reconstruction is based on the records from the sediment cores 22-GC3, 22-GC8 and 25-GC1, and provides information on vegetation successions in Northern Anatolia and on changes in the Black Sea sea-surface conditions. The pollen data reveal the dominance of Artemisia steppe in Northern Anatolia during glacial stadials, suggesting rather dry/cold conditions. Temperature and humidity increased during the last and penultimate deglaciations and the last glacial interstadials, which is clearly indicated by development of oak and pines forests. This development can be explained by northwards movement of the summer position of westerlies. The onset of the interglacial conditions in Northern Anatolia is reflected by establishment of euxinian forests. The main difference in both interglacial pollen records is the relatively high amount of the submediterranean Ostrya-type during the Eemian, indicating warmer summer temperatures, compared to the Holocene. The wide distribution of Fagus in Northern Anatolia during the Eemian contrasts with the European records and could be explained by climatic and genetic factors. Pollen assemblages indicate a reduction in forest cover after 5 ka BP, possibly caused by an increased anthropogenic pressure on the vegetation. The dinocyst record indicates lacustrine conditions in the Black Sea during the glacials and shows a change from freshwater/brackish assemblages (Pyxidinopsis psilata, Spiniferites cruciformis) to more marine assemblages (Lingulodinium machaerophorum, Spiniferites ramosus complex) in the Eemian and the Holocene, due to the inflow of saline Mediterranean water. Dinoflagellate cyst assemblages (Tuberculodinium vancampoae, Spiniferites pachydermus, S. mirabilis, Bitectatodinium tepikiense) suggest relatively high sea-surface salinity (~28-30) and sea-surface temperatures during the Eemian, comparing to the Holocene (~15-20). The establishment of high sea-surface salinity during the Eemian correlates very well with relatively high global sea-level and is explained as a combined effect of increased Mediterranean supply and increased evaporation at the beginning of the last interglacial. The first results of the comparison of pollen spectra from surface of the Black Sea core 22-GC3 with such from surface samples collected in Northern Anatolia suggest that the main pollen source area for cores 22-GC3/8 is the adjacent coastal regions of Northern Anatolia and adjacent northern slopes of the Pontic Mountains.