Problems of Stratigraphy of the Cenozoic Coal-Bearing Formation in Primorye, the Russian Far East

Analysis of paleobotanical data on the Cenozoic of the Pavlovka Coal Field as a typical coal-bearing formation in Primorye revealed the absence of Neogene coal-bearing deposits. In some Tertiary coal-bearing structures in Primorye, coal formation processes continued in the Oligocene–Miocene transition, albeit on a reduced scale. In younger parts of the Cenozoic complex, coal content is either reduced to noneconomic proportions (Lower Miocene) or is absent from the Middle Miocene onward. A similar situation is characteristic of regions adjacent to Primorye. Possible reasons for the cessation of coal formation processes at the Neogene transition are global climate deterioration, which reduced the bioproductivity of vegetative associations, and a change in sedimentation basin redox conditions from a reducing geochemical environment to an oxidizing one triggered by explosive volcanism, which blocked the preservation of plant mortmass.