Mantle resistance against Gibraltar slab dragging as a key cause of the Messinian Salinity Crisis

Abstract

The Messinian Salinity Crisis (5.97–5.33 Ma) was caused by the closure of the Atlantic-Mediterranean gateways that cut through the Gibraltar orogenic system. The geodynamic drivers underlying gateway closure and re-opening are still debated. Here, we interrogate the gateway successions to find the imprints of surface deformation, infer the timing and nature of associated geodynamic drivers, and test such inferences against numerical simulations of slab dynamics. We find that since the latest Miocene, a tectonic framework was established in the gateway region dominated simultaneously by (a) relative plate convergence, (b) slab tearing under the eastern Betic Cordillera and (c) mantle resistance against north-northeastward dragging of the Gibraltar slab by the African plate's absolute motion. We propose that mantle-resisted slab dragging and slab tearing operated in concert closing the gateways that caused the Messinian Salinity Crisis, whereas sinking of heavy oceanic lithosphere located between buoyant continental plates re-opened the Strait of Gibraltar at 5.33 Ma.