THE PALEOGENE/NEOGENE BOUNDARY IN CONTINENTAL DEPOSITS OF THE WEST SIBERIAN PLAIN
V.S. Volkova1, O.B. Kuz’mina1, Z.N. Gnibidenko1, A.G. Golovina2
1A.A. Trofimuk Institute of Petroleum Geology and Geophysics, Siberian Branch of the Russian Academy of Sciences, pr. Akademika Koptyuga 3, Novosibirsk, 630090, Russia
2Siberian Research Institute of Geology, Geophysics, and Mineral Resources, Krasnyi pr., 67, Novosibirsk, 630091, Russia
Keywords: Continental lacustrine deposits, Turtas, Zhuravka, and Abrosimovka Formations, palynology, magnetostratigraphy, upper boundary of the Oligocene, West Siberia
Abstract
The paper presents palynologic and paleomagnetic characteristics of three West Siberian horizons are presented: Zhuravka (Upper Oligocene, Chattian), Abrosimovka, and Beshcheul (Lower-Middle Miocene, Aquitanian, Burdigalian, Langhian, and Serravallian). We consider the distribution of dinocysts of the genus Pseudokomewuia in the stratotype section of the Zhuravka Horizon (Zashchitino Village) and in the section of borehole 13 (Chelyuskintsev Village), which exposes the Turtas, Abrosimovka, and Beshcheul Formations. Similar compositions and structures of dinocyst assemblages and similar palynofloras in the Turtas and Abrosimovka Horizons, as well as the sedimentation environment and cyclic structure of lacustrine deposits, suggest that the Paleogene/Neogene boundary should be localized at the base of the Beshcheul Horizon. We propose to include the Abrosimovka Horizon into the Upper Oligocene (upper Chattian). The data are correlated with the regional paleomagnetic scale. These views should be reflected in a new regional stratigraphic chart for the Paleogene-Neogene deposits of the West Siberian Plain.
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