Apsheron Threshold and Its Role in the Processes of Sedimentation and Formation of Hydrological Regimes in the Southern and Middle Caspian Basins

It is shown that, in the Late Cenozoic, the Apsheron threshold was a natural boundary between the sea and lake–sea basins in the southern and middle Caspian regions. It is established that the lithological–petrographic composition and structure of the bottom sediments in the adjacent southern and middle Caspian basins were formed independently, or the interaction between them was very limited.