Late Oligocene and Miocene climate and vegetation in the Eastern Paratethys area (northeast Bulgaria), based on pollen data

The results of palynological studies of the Oligo-Miocene in the western part of the Euxinian Basin (Eastern Paratethys) are based on the analysis of 57 samples from core C-136A drilled near the town of Balchik, Varna district. Some samples were barren or contained very little pollen and were not included in the analysis. Quantitative data are thus confined to 26 polleniferous samples. We present results for the Upper Oligocene as well as the Tarkhanian, Karaganian, Bessarabian, and Chersonian stages of the middle to upper Miocene.Mixed deciduous forests were widespread during the time period studied. Swamp forests are also recorded, with distribution maxima observed in the Oligocene and in the Bessarabian. The widest extent of herbaceous vegetation is recorded in the late Bessarabian and Chersonian, when it occupied open landscapes after a marine regressional phase.The climatic data reconstructed by the Coexistence Approach indicate mean annual temperatures (MATs) of ca. 15–17 °C and mean annual precipitation (MAPs) of 800–1300 mm for the Upper Oligocene. The narrowest coexistence intervals of the Tarkhanian and Karaganian display MATs of 14–17 °C and MAPs of 800–1300 mm. The most substantial data are for the Bessarabian, in which the lower part is characterized by MATs of 15.6–16.6 °C and MAPs from 800–1200 (1300) mm. The results for the upper part of the Bessarabian are more variable, especially with respect to precipitation that is generally lower (700–800 mm). The same is true for the Chersonian, where besides lower precipitation, lower annual temperature and temperature of coldest month are observed. These results correlate with previous vegetation and palaeoclimate data from the Forecarpathian Basin (NW Bulgaria).