The demise of Paratethys in the time of the Messinian Salinity Crisis: impact on Eurasian paleogeography and Mediterranean environments

Abstract

During the Messinian Salinity Crisis (MSC), as the Mediterranean realm experienced partial desiccation, water levels in Paratethys, a vast waterbody in the middle of Eurasia, remained largely unaffected except in its easternmost domain, the Caspian basin, which experienced a severe partial desiccation. Still, its relation and role in the dynamics of the MSC are controversial.Here we reconstruct the paleogeographic evolution of the Paratethys region during the MSC. We  show that the Paratethys realm irreversibly fragmented into smaller basins (Dacian, Black Sea, Caspian) triggering a reorganization of the Paratethys watershed during the MSC. The Paleo-Don River, the main river flowing in Paratethys, was captured by the Black Sea basin enhancing the excess of water was spilled in the Mediterranean and affecting the hydrology of the Mediterranean during the Lago Mare phase of the MSC. The Caspian basin, isolated and deprived of major river inflows, became partially desiccated, experiencing a ~400m base level drop. Extensive canyons developed and expanded in the central-northern Caspian Basin forming a new river - the Volga, that would later capture the eastern watershed of the Paleo-Don and partially refill the Caspian basin. These findings reveal that the MSC had extensive, continental consequences: destabilizing the Paratethys realm and reorganizing the river networks of Eastern Europe. This paleogeographic reorganization and the shifts in freshwater budgets may represent a key piece of the puzzle of the water balance in the Mediterranean basin during the MSC.