Home – Home – Jornals – Russian Geology and Geophysics 2003 number 4

A combined palynological and paleomagnetic study of core samples of Upper Cretaceous and Cenozoic deposits from four boreholes drilled in the Upper Ob' region has been carried out to provide materials for the State Geological Map-200. Palynological and paleomagnetic descriptions have been performed. Fourteen spore-and-pollen assemblages have been recognized in the deposits under study. They characterize the marine Eocene (Lyulinvor and Tavda Horizons), continental Paleogene (Atlym, Novomikhailovka, and Zhuravka Horizons), and Neogene (Abrosimovka, Beshcheul, Tavolzhan, and Pavlodar Horizons). Features of flora changes at Cenozoic borderlines (Eocene-Oligocene, Oligocene-Miocene, and Middle-Late Miocene) and their stratigraphic significance are outlined. A paleomagnetic section has been compiled for borehole 10. It includes 19 major magnetozones of different polarities: nine in the Paleogene, eight in the Neogene, and two in the Quaternary. They correspond to the rank of orthozones, paleobotanically characterized and referred to the regional stratigraphic scheme. Some of these orthozones are referred to the Berggren time scale. All these data allowed subdivision of the Upper Cretaceous and Cenozoic deposits under consideration, estimation of the completeness of the section, rock dating, and refinement of the stratigraphic volume of the Upper Cretaceous and Cenozoic formations and regional horizons exposed in the boreholes.