Iberia, a natural laboratory for the quantification of the large scale erosional response to the fluvial capture processes

Abstract

Due to its geological location and diversity, Iberia is a key natural laboratory for the study of tectonic and geological processes. Within those it is especially suitable for the study of large-scale fluvial capture processes, and their influence on topography and landscape evolution. Nowadays, Iberia is characterized by the presence of highly elevated extensive flat surfaces (Iberian Mesetas). Those high plains correspond to planation surfaces developed mainly on Palaeozoic and Mesozoic rocks, and sedimentation surfaces of Neogene rocks. These last mostly represent the sedimentary deposits related to infill of the, formerly closed Foreland Basins. Three main rivers (Duero, Ebro and Tajo) which watersheds cover an area over 250 km2, drain almost half of the total Iberia surface. For these basins the development of the present-day drainage network was related to the opening of formerly closed fluvial systems, developed within ancient Cenozoic basins. In The Iberian Peninsula, the signature of that change in drainage conditions is still preserved in some areas, and can be studied through the analysis of longitudinal profiles shapes and the relief characterization. The analysis of present and former topography represents a powerful qualitative tool for a relative quantification of fluvial dissection and basin denudation, allowing to illustrate the spatial distribution of surface erosion, associated to the exorheic history of the basins. This work approaches the analysis of the denudation processes for the main formerly endorheic Iberian basins.