Limit Cycle Model of Messinian Salinity Crisis Incorrect and Irreproducible

Abstract

<p>During the Messinian Salinity Crisis (5.97-5.33 Ma), evaporite deposition throughout the Mediterranean basin records a<br>series of dramatic environmental changes as flow through the Strait of Gibraltar was restricted. In the first stage of<br>evaporite deposition, cycles of gypsum appear in shallow basins on the margins of the Mediterranean. The complex<br>environmental history giving rise to these cycles has been investigated for decades but remains somewhat mysterious.<br>Notably, whether the evaporites are connected to significant changes in Mediterranean sea level is an open question.<br>In one proposed model, competition between tectonic uplift and erosion at the Strait of Gibraltar gives rise to self-sustaining<br>sea-level oscillations, or limit cycles, which trigger evaporite deposition. I show that limit cycles<br>are <strong>not a robust result of the proposed model</strong> and discuss how any oscillations produced by this model depend on<br>an <strong>unrealistic formulation of a key model equation</strong>. A more realistic formulation would render sea-level limit cycles improbable,<br>if not impossible, in the proposed model.</p>