Dense shelf water cascading and Messinian Canyons: A new scenario for the Mediterranean salinity crisis

• DOI: 10.2475/05.2014.03
• Publication Date: 2014-05-02T17:29:41Z
• Authors: M. Roveri; V. Manzi; A. Bergamasco; F. M. Falcieri; R. Gennari; S. Lugli; B. C. Schreiber
• Keywords: 550; Messinian salinity crisis; evaporite; submarine canyons; evaporites; 01 natural sciences; 3. Good health; Messinian salinity crisi; 13. Climate action; Messinian salinity crisis; Mediterranean Sea; dense shelf water cascading; evaporites; submarine canyons; Mediterranean Sea; 14. Life underwater; dense shelf water cascading; 0105 earth and related environmental sciences

he salt giant beneath the deep Mediterranean seafloor is the impressive record of the Messinian salinity crisis, a dramatic event that occurred about 6Ma ago following the reduction of the connections with the Atlantic Ocean. According to the shallow-water deep-basin model, developed for these deposits (Hsü and others, 1973a, 1973b, 1978a, 1978b), the Messinian evaporites formed in a deep but desiccated Mediterranean, while shelves and slopes underwent subaerial erosion due to fluvial rejuvenation triggered by a 1500 m sea level drawdown. Deeply incised Messinian canyons in the continental slopes surrounding the Mediterranean are the main argument supporting this scenario. Using a state of the art model and idealized but realistic numerical simulations, here we demonstrate that the activation of downslope flows of hypersaline, dense waters, in a process similar to present-day dense shelf water cascading, but much more energetic, may account for both slope erosion and progressive salinity rise leading to the formation of deep-seated supersaturated brines. Our findings support a deep-water deep-basin model (Schmalz, 1969, 1991; De Benedetti, 1976, 1982; Dietz and Woodhouse, 1988), thus implying that evaporite deposition may have occurred in a non-desiccated basin with strongly reduced ocean connections.