A groundbreaking study published in Nature Communications has shed light on the ancient Mediterranean Salinity Crisis, revealing its profound effects on the region's flora and fauna. Conducted by an international research team led by Giovanni Aloisi from the CNRS and the Institute of Physics of the Globe of Paris, the study utilized stable chlorine isotopes to reconstruct the precipitation of salt deposits over time.
The Mediterranean Salinity Crisis, which occurred between 5.97 and 5.33 million years ago, was marked by a drastic reduction in water inflow from the Atlantic Ocean. This led to the Mediterranean transitioning from a sea to a hypersaline basin and eventually to a freshwater or brackish lake. The research indicates that this process unfolded in two distinct phases, with significant implications for the region's ecosystem.
During the initial phase, lasting around 35,000 years, salt accumulation occurred primarily in the eastern Mediterranean due to reduced water outflow towards the Atlantic. In the second phase, a rapid evaporation event caused widespread salt deposition across the entire Mediterranean in less than 10,000 years, resulting in dramatic sea level drops of up to 2.1 kilometers in the eastern basin.
The study's findings resolve long-standing scientific debates regarding the mechanisms of salt deposition and highlight how the crisis led to the separation of the eastern and western Mediterranean. This division influenced the biological and geological evolution of the region, including the emergence of a land bridge between Africa and Europe, facilitating the exchange of species that shaped the biodiversity of the Balearic Islands.
Moreover, the reduction of water mass on the lithosphere likely triggered widespread magmatic uplift across the Mediterranean area. Ongoing research efforts, supported by various international collaborations, continue to explore the implications of this ancient crisis on current climate and ecological dynamics.