Stratigraphy of the Lower and Middle Turonian (Upper Cretaceous) of the Yenisei (Left Bank) Part of West Siberia by Inoceramids and Foraminifers

Abstract—: The results of lithobiostratographic study of the lower part of the Late Cretaceous marine section are presented for the territory of the Bol’shaya Kheta structural terrace on the left bank of the Yenisei River in its lower reaches (the upper parts of the Dolgan Formation, the Dorozhkovo Formation, and the lower parts of the Nason Formation; Turonian Stage). Eleven lithological members are traced in the territory and paleontologically characterized. The layers with fauna (inoceramids and foraminifers) are distinguished and compared with zonal Turonian subdivisions of West Siberia. It is found that the upper part of the Dolgan Formation belongs to the lower substage of the Turonian, Mytiloides labiatus Zone. The Dorozhkovo Formation in the region, which is close to its stratotypic locality, corresponds to the lower and middle Turonian.