Improvement of the Neogene Zonal Diatom Scale of Primorye (Russia)

To study diatoms from some Neogene stratotype sections of Southern Primorye—the Sineutesovskaya and Novokachalinskaya formations and the Shufansky Horizon, light and scanning electron microscopy were used. The data allowed corrections to the existing Zonal Diatom Scale of the Neogene of Primorye. Studies have shown the absence of some zone index species in the deposits: Alveolophora bifaria, A. jouseana, and A. areolata. As a result, the subdivisions of the scale were renamed: Alveolophora hachiyaensis–Aulacoseira elliptica Zone, Alveolophora khankaica Zone, Alveolophora khursevichiae Zone. The position of the Shufansky horizon zones has changed: the Aulacoseira praeislandica Zone now corresponds to the Early Pliocene, and the Alveolophora tscheremissinovae Zone—to the Late Pliocene. According to the International Stratigraphic Chart of the Cenozoic, the age of the upper boundary of the Alveolophora tscheremissinovae Zone is 2.58 Ma.