Incision and uplift controlling water flow through the strait. Towards a mechanistic model for the Messinian Salinity Crisis

Abstract

Though many researchers envisage a primary tectonic control behind the onset and the termination of the Messinian Salinity Crisis, quantitative models have not yet evaluated the effect of the uplift of the barrier separating both oceanic domains, and neither have they addressed the counteracting effect of water-flow incision. Evidences for more than 300 m of incision across the Gibraltar strait, based on recent drilling cores and new seismic profiles, show that incision was a key control on the post-Messinian flood, the abruptness of which remains poorly constrained. A simple quantitative model is here proposed that couples hydrodynamic equations with an incision model constrained by previous calibrations in mountain rivers. The results indicate that the post-Messinian flood was a catastrophic event that reached peak discharges of about 108 m3/s (about 1000 times the present Amazon River), producing incision rates above 0.4 m/day, and raising the level of the Mediterranean rose at a peak rate of at ~10 m/day. The same formulation is then used to study the role of uplift during the process of isolation of the Mediterranean.