Late Cenozoic Evolution of Northern Eurasian Marginal Seas Based on the Diatom Record

Abstract

Based on an analysis of fossil diatom assemblages in the upper Cenozoic beds of the northernmost Eurasian coast and adjacent shelf areas and their correlation with zonal stratigraphical subdivisions of the sub-Arctic regions of North Atlantic and North Pacific the spatial-temporal evaluation of the main paleoceanological events in the Arctic have been established.The similarity of the Late Cenozoic diatom floras of the eastern Arctic and the North Pacific existed since the Middle Miocene.The end of the Middle Miocene as well as the Late Miocene were the epochs of transgressions on the eastern Eurasian Arctic shelf.Sea basins occupied coastal lowlands of northern Chukotka, the shelves of the East Siberian and Laptev Seas, and the region around the New Siberian Islands.A deep ingressive bay occupied the North Siberian lowland and reached the Ust' -Yenisei region.The Middle Miocene diatom assemblages of the eastern Arctic seas are charactcrized by a high taxonomic diversity of the warm water species, the Late Miocene ones by the abundance of cold water species and the appearance of Arctic-boreal species including sea-ice species.The end of the Late Pliocene and early to middle Pleistocene epochs in the Eurasian Arctic shelf regions were marked by marine transgressions.Paleoceanological and ice conditions in the Arctic seas during this time were close to the modern ones, being affected by continuous intensive advection of North Atlantic and Pacific waters.