Tectonic Setting and Landscape Development

Abstract

The Mediterranean is the westernmost part of the global-scale Alpine-Himalayan orogenic belt which stretches from Spain to New Zealand. The landscapes of the region have a long and complex history that includes both horizontal and vertical crustal movements and the creation and destruction of oceans. This began with the break up of the super-continent Pangea around 250 Ma, which generated the Tethys Ocean—the forerunner to the present-day Mediterranean Sea. Collision of the African and European tectonic plates over the last 30 Ma led to the destruction of the Tethys Ocean, although a few remnants of its geology are preserved within the eastern Mediterranean. It is the collision of Africa and Eurasia, and the associated tectonics that have been largely responsible for generating the Mediterranean Sea, its subsequent history, and the landscapes that surround it. This collisional history progressively reduced the connectivity of the Mediterranean Sea with surrounding marine bodies by closing and restricting marine gateways. During the Miocene, for example, the Mediterranean basin became completely isolated from surrounding marine bodies in what is known as the ‘Messinian Salinity Crisis’. This period saw major changes to the regional water balance leading to evaporation and draw-down of the Mediterranean Sea. This had profound impacts on all aspects of the physical geography of the region including the climatology, biogeography, and geomorphology and its legacy can be seen across the region today. The more recent Quaternary geodynamics of the Mediterranean have generated an area which includes a complex mixture of zones of plate subduction of various ages and stages (Figure 1.1b). The modern Mediterranean includes zones of active subduction associated with volcanic activity—such as the Calabrian arc—and older zones of now quiescent subduction such as the Betic-Rif arc. There is a wide range of seismic activity associated with these regions from deep (600 km) to shallow (<50 km) and ranging in magnitude up to 8.0Mw (earthquake moment magnitude; a quantitative and physically based scale for measuring earthquakes).