The Southern Baltic Seas in the Paleogene according to the study of the foraminifera

The changes in the paleocomplexes of the foraminifera, the remains of other organisms, and the lithological composition of the Paleogene deposits in the Kaliningrad region made it possible to reconstruct the sedimentation conditions during the Paleogene. In the Early Paleocene, within the territory of the Southern Baltic region, there was a shallow lightly salted bay of the Northwestern European Sea. In the Middle Paleocene, as a result of the intensive but short-lived transgression, it was transformed into a wide normally salted sea basin up to 200 m deep. At the end of the Middle Paleocene, it gradually became shallow, which caused the sea’s disappearance in the Late Paleocene. The new transgression from the west started in the second half of the Middle Eocene, and, after the Mazuro—Belorus Rise and the Poless saddle sank, the South Baltic became a part of the latitudinal communication system that connected the North Atlantic and the Tetis Ocean. The influence of the Tetis Ocean became stronger in the Late Eocene, when the water temperature was the highest in the northern part of the sea bay during the whole Paleogene. In the early Oligocene, the connection of the South Baltic Sea and the Tetis Ocean discontinued, and, in the Late Oligocene, the continental conditions were established in the South Baltic.