Ranges and basins in the Iberian Peninsula: Their contribution to the present topography

The Iberian Peninsula, at the western end of the Alpine - Himalayan Belt, displays a complex structure with mountain ranges of diverse structural trends and sedimentary basins between them. The Iberian Peninsula also shows an elevated mean topography, the highest in Europe. In this short paper, we investigate the Alpine evolution of the Iberian Peninsula since Mesozoic times, when Iberia was isolated as an independent plate. This occurred from Albian (formation of the northern plate boundary) to Oligocene times (end of the Pyrenean Orogeny). Iberia was squeezed between Africa and Europe during Tertiary times and all previously established Mesozoic extensional basins were inverted, as were some of the Hercynian structures. The opening of the Valencia Trough, cutting the eastern margin of the Iberian Peninsula, began in Oligocene times. Concomitant crustal and lithospheric stretching during the Neogene along the eastern margin of Iberia produced limited uplifts, some of which are still active. The modern topography of the Iberian Peninsula was developed mainly as the result of three main tectonothermal mechanisms since late Palaeozoic times: variations in crustal densities, and possibly mantle depletion, inherited from the Hercynian Orogeny; crustal and lithospheric thickening during Tertiary compression; and upper mantle thinning during the Neogene - Quaternary.