Chronology of vegetation and paleoclimatic stages of northwestern Russia during the late glacial and Holocene.

Abstract

We have studied 6 reference sections of bog and lake sediments in the Leningrad and Novgorod provinces to develop a geochronological scale for vegetational and paleoclimatic changes in northwestern Russia during the Late Glacial and Holocene. Every 10-cm layer along the peat and gyttja sections (4-8.5 m thick) was investigated palynologically and the great majority of them were radiocarbon dated. Using the data obtained, standard palynological diagrams were plotted and vegetation history reconstructed. The palynozones indicated on the diagrams were related to the climatic periods and subperiods (phases) of the Blytt-Sernander scheme. On the basis of 230 (super 14) C dates obtained, we derived the geochronology of climatic periods and phases, as well as the chronology for the appearance and areal distribution of forest-forming tree species. The uppermost peat layers were dated by using the "bomb effect". We compared the stages of Holocene vegetation and paleoclimatic changes discovered for the Leningrad and Novgorod provinces with the those obtained for Karelia, which we had studied earlier using the same methodology.