Climate and vegetation change during the late Miocene in southwest Bulgaria based on pollen data from the Sandanski Basin

Late Miocene sediments from the Sandanski Basin in southwest Bulgaria are studied by means of the spore and pollen analysis. Vegetation in the studied basin is described and its dynamics and development are traced out. The main vegetation types are distinguished. The flora of this time interval was characterized by a change in the structure of communities and of the dominant species. Quercus, Castanea, Corylus, Ulmus, and Carya used to prevail in the composition of mesophytic forest paleocoenoses. Paleogeographic and climatic changes at the beginning of late Miocene had determined the emergence of suitable conditions for a broader participation of herbaceous coenoses. The first herbaceous coenoses were comparatively poor in their taxonomic composition, which became enriched for the first time in the late Tortonian. The traced-out dynamics of paleoclimatic data testify to notable climatic changes. The beginning of the late Miocene witnessed a certain drying and slight cooling, resulting in a moderately warm climate. It had a distinct seasonality with respect to temperature and precipitation.