Palaeoclimatic reconstruction of the last deglaciation (18-8 ka B.P.) in the Adriatic Sea region; a land-sea correlation based on palynological evidence

Abstract

Current latest Pleistocene-early Holocene palaeoclimatic reconstructions for the Adriatic Sea region (Eastern Mediterranean) are still controversial, suggesting either dry or humid conditions for the interval between 18 and 8 ka B.P. These reconstructions are derived from either marine or terrestrial records which are rarely considered together and are often based on only few datapoints. Intercorrelation of both marine and terrestrial, high time-resolution records is required to obtain a more realistic reconstruction. In this paper a palynological approach to such a high resolution, land-sea correlation is presented. Sediments from a well-dated core in the southern Adriatic Sea have been studied for their dinoflagellate cyst and pollen content. Changes through time in the composition of the dinoflagellate cyst association, provide information about palaeoenvironmental change in the marine realm, whereas changes in the pollen association provide information about environmental changes on the continent. Correlation of these records indicates that from 18 to 13.2 ka B.P. (glacial period) cold, dry climatic conditions existed in the Adriatic Sea region. At the end of this period increased discharge by the Po river can be identified, corresponding to a melting phase of glaciers in the Alps and Apennines. Between 13.2-11 ka B.P. (Bölling/Allerød) temperatures increased. Two additional intervals with steadily increasing Po river discharge have been identified between 12.8-12.2 ka B.P. and 12-11.2 ka B.P. with maximum discharge at 12.2 ka B.P. and at 11.2 ka B.P. These increases in discharge are probably due to enhanced winter precipitation since vegetation reconstructions, based on pollen records from terrestrial deposits, indicate no increase in spring/summer precipitation; moreover, there is no evidence of increased melting of glaciers in the Alps and Apennines in these intervals. Between 11-10 ka B.P. (Younger Dryas) the climate became cold and dry again. At the end of the Younger Dryas a fourth interval with increased Po river discharge can be observed which correlates to a second melting phase of Alpine and Apennine glaciers. After 10 ka B.P. (Holocene) climatic conditions became more warm and humid.