FIRST FINDS OF FOSSIL POLLEN OF THE DECODON GENUS IN THE OLIGOCENE AND MIOCENE IN THE SOUTH OF WESTERN SIBERIA AND THEIR BIOGEOGRAPHICAL DISTRIBUTION FEATURES

Palynological analysis of Upper Paleogene and Neogene deposits in the south of Western Siberia (Borehole 2, Novosibirsk Oblast) showed that pollen of the genus Decodon J.F. Gmel. (Lythraceae), previously unknown in this region, is present in the spore-pollen spectra. A morphological description and comparative analysis of the identified pollen grains with the pollen of modern Decodon verticillatus (L.) Ell. and with fossil pollen of the genus Decodon from Cenozoic deposits of North America, Europa and China are given. The distribution of Decodon sp. pollen in the Oligocene and Miocene section of the southern West Siberian Plain is shown: single specimens have been recorded in the Novaya Mikhailovka Formation (Lower Oligocene), such pollen was also noted in the Zhuravka (Upper Oligocene) and Abrosimovka (Lower Miocene) formations, and the largest amount of it comes from the Beshcheul Formation (Lower-Middle Miocene); such pollen has not been found in Upper Miocene deposits.

The fossil pollen finds of the Decodon genus in Western Siberia are important for determining the geological age of the deposits, as well as for reconstructing the sedimentation conditions in the Oligocene and Miocene. They will serve as a valuable addition to the generalization of the history of the distribution of representatives of this genus, which spans about 78 million years, their evolution and migration between continents in the Cenozoic.