History of Paratethys

The history of the formation, evolution, and disappearance of the inland giant Paratethys sea is considered from the time of its formation in the middle of the Cenozoic (34 million years ago) to the final separation of its waters into the Black and Caspian seas at the end of the Miocene epoch (5.6 Ma). The history of Paratethys and the organisms inhabiting it was mainly determined by its connections with oceans. Their expansion led to the uprising of the Paratethys water level to that of the World Ocean, and subsequently, its colonization by marine organisms. The drying of the straits turned Paratethys into a huge lake. The level and salinity of its waters depended on the ratio of river runoff and evaporation: with a positive water balance, the basin began to expand and desalinate, with a negative one, it regressed, saline bays and lagoons appeared in it. Obviuosly, marine biota had died in such conditions and only some organisms were able to tolerate abrupt changes in salinity, ion and oxygen regimes promoted development of specific brackish-water groups of fauna. The existing ideas about the paleogeography of this basin well reflect the intervals of high sea water levels, but do not address the results of rather signifi cant drops in sea level during its trapped episodes. Until recently, paleogeography had no appropriate methods to reconstruct such stages. Only now, with the development of seismostratigraphy, it has become possible to assess the scale and spatial patterns of paleogeographic changes with signifi cant basin reductions during regression periods.

Paleogene, Neogene, sea level, transgression, regression, seismostratigraphy