History and Causes of Variations in the Caspian Sea Level: the Miopliocene, 7.1–1.95 Million Years Ago

Abstract

It is shown that the awareness of the regularities and causes of variations in the Caspian Sea level from the moment of its origin as an isolated lake basin in the Late Miocene (7.2 mln years ago) is of great importance for paleohydrology. Out of the seven principal hydrologic stages of the Caspian Sea history, four stages are considered in this paper: two lake stages (the Late Miocene and Middle Pliocene), the intermediate stage when the Caspian and Zanklinian basins were connected, and the stage of the Manych runoff. An important fact in the Caspian Sea history is emphasized: penetration of the Akchagylian fauna forebears into the Caspian Sea Basin through the Black Sea and the nowadays nonexistent Kuban–Terek Channel (between 5.3 and 3.3 mln years ago). Three phases of penetration of the Mediterranean Zanklinian fauna into the Caspian Basin are recognized. The channel became “closed” during the Middle Pliocene phase of the Great Caucasian Range elevation (3.3–2.5 mln years ago). This isolation of the Caspian Basin caused the formation of the Great Akchagylian Lake. Its water washed out the New Manych Channel 2.5 mln years ago. From this moment on, the events that occurred in the Caspian Basin and in the Black and Mediterranean seas can be correlated in greater detail, “link by link”, within the 413-thousand-year period of water abundance.