Palynostratigraphy of Paleogene and Neogene sediments of the Baraba-Kulunda facies zone of West Siberia

We report new data on stratigraphic validation of the age of marine Paleogene and continental Paleogene-Neogene sediments exposed in three boreholes in the Omsk Irtysh area, West Siberia. Based on dinoflagellate, spore and pollen specimens, we describe two formations, Lyulinvor and Tavda, in the marine Paleogene. Two dinocyst zones, termed Dracodinium varielongitudum-D. simile and Charlesdowniea coleothrypta rotundata-Ch. coleothrypta according to their index species, are established in the Lyulinvor Formation. These zones correspond to the nannoplankton zones 11-14. The sediments are dated Lower-early Middle Eocene (Ypresian-lower Lutetian). The Tavda marine formation also includes two dinocyst zones: Rhombodinium draco-Areosphaeridium dictyoplocus and Charlesdowniea clathrata angulosa, correlated with the nanoplankton zones 16-19. This formation is dated late Middle-Upper Eocene (upper Lutetian-Bartonian-Priabonian). We describe eight palynological assemblages from the continental Paleogene and Neogene deposits and substantiate the establishment of the Zhuravka, Abrosimov, Beshcheul', and Tavolga Formations in the boreholes. Three stages of vegetation development are described: tropical, Turgai, and post-Turgai.