Paleontological and magnetostratigraphic data on Upper Cretaceous deposits from borehole no. 8 (Russkaya Polyana District, Southwestern Siberia)

This work presents results of complex research (palynological, macro- and microfaunistic, and paleomagnetic) of Upper Cretaceous deposits, opened by borehole no. 8 in the Russkaya Polyana District (the southern margin of the Omsk Depression, Southwestern Siberia). The paleontological data obtained allowed us to establish the age of deposits. Based on dinocysts, nannoplankton and spore-pollen complexes, the section of borehole no. 8 has been divided into Pokur, Kuznetsovo, Ipatovo, Slavgorod, and Gan’kino Formations. This work gives data on the composition of zonal palynomorphs, nannoplankton, and microfaunistic complexes. Based on the complex data obtained, the magnetostratigraphic section of Upper Cretaceous deposits has been developed. The section consists of three magnetozones: normal and two reversed polarity magnetozones. The Pokur, Kuznetsovo and Ipatovo Formation (Cenomanian-Santonian) belong to the long normal polarity magnetozone; the Slavgorod and Gan’kino Formations (Campanian-Maastrichtian), separated by a stratigraphic break, belong to reversed polarity magnetozones. The magnetostratigraphic section has been correlated with the general magnetostratigraphic and magnetochronological time scales.