Early Eocene Diatoms and Silicoflagellates of the Cis-Donets Monocline (Russian Plate): Biostratigraphical and Paleogeographical Approaches

Abstract

Abstract The diatom assemblage of the Veshenskaya Formation studied in the borehole P-321 of the Cis-Donets monocline (southern part of the Russian Plate) is assigned to the lower Ypresian Moisseevia uralensis Zone. According to the available data, this zone corresponds to the Deflandrea oebisfeldensis and Dracodinium (=Wetzeliella) astra dinocyst zones and, accordingly, to the nanoplankton NP10 Zone. The presence of the zonal silicoflagellate species Naviculopsis foliacea confirms the Early Eocene age of the Veshenskaya Formation. The taxonomic similarity of diatoms and silicoflagellates of the region under consideration with silicofossil assemblages of Northern Europe suggests a stable link between these paleobasins at the beginning of the Early Eocene.