Silicofossils and Dinocysts of the Lower Paleogene Siliceous–Terrigenous Deposits, South Russian Plate: Their Significance for Dating of Sedimentary Sequences

Eocene silicofossils (diatoms and silicoflagellates), dinoflagellate cysts, and continental palynomorphs of two boreholes in the Cis-Donetsk and Pavlovsk–Kantemirovka structural-facies zones of the Donets Syncline were studied. The Veshenskaya Formation, characterized by the dinocyst assemblage of the Stenodinium meckelfeldense Zone, is assigned to the early Ypresian. The Tishki and Kasyanоvka formations, with assemblage of the Bipalla oamaruensis diatom zone and first appearance of silicoflagellate Corbisema hexacantha, as well as a dinocyst assemblage with Enneadocysta pectiniformis, are dated as the late Lutetian–early Priabonian. The microfossil assemblages are typical of shallow-water marginal parts of the epicontinental paleobasin.