Problem of Stratigraphic Boundary between the Paleogene and Neogene Systems in the Eastern Paratethys

摘要

To clarify the problem of boundary between the Paleogene and Neogene Systems within the limits of the Eastern Paratethys on the territory of Georgia the sections represented by coastal and deep-marine facies were studied comprehensively (micro- and macrofauna, nannoplankton). The stratotype section represented by coastal facies is exposed in Eastern Georgia in the vicinity of the village of Uplistsikhe and it contains numerous (more than 10) mollusk forms of Aquitanian age (=Uplistsikhe stage). According to mollusk fauna preserved in this section the stratiform boundary in the above-mentioned sections is to be drawn between the Upper Oligocene (Pharekhi suite) sediments containing subsaline fauna and norm marine ones that are characterized by mollusk species of Aquitanian age (=Uplistsikhe stage). Good results were obtained during the study of carbonate nannoplankton when investigating the so-called mute clays of the Maikop series represented by deep-sea fades. Based on the data of this group we managed to draw the boundary between the Paleogene and Neogene sediments on the considerable territory of Georgia; NP25 (Spenolithus ciperoehsis) nannoplankton zone of uppermost Oligocene and NNI (Triquetrorhabdulus carinatus), it pass between the nannoplankton zones - NP25 (Spenolithus ciperoehsis) of uppermost Oligocene and the lowermost NNI (Triquetrorhabdulus carinatus) of the Miocene.