The role of lithospheric heterogeneities in the location of the Cenozoic intraplate deformation of Iberia from finite element modeling

Abstract

The Cenozoic evolution of the Central System basement uplift and of the continental Duero and Madrid basins on the Iberian Peninsula occurred in a compressive context triggered by the Alpine orogeny. Although several models of deformation have been suggested, the factors that led to the development of these have not been analyzed to date. We present here finite element modeling of the intraplate deformation of the Iberian lithosphere during the Cenozoic. This modeling has taken into account the role played by (1) the tectonic shortening originating from the Pyrenean and Betic collisions, (2) the weight of Tertiary continental sediments, and (3) thermomechanical heterogeneities present in the lithosphere. The numerical model represents a lithospheric section, with a creep-type mechanical behavior, perpendicular to the Central System, and the two sedimentary basins. Both initial conditions and the results obtained have been specified based on the available geophysical and geological data. This study has enabled us to simulate the present lithospheric structure of the central Iberian peninsula: (a) the formation of the Central System relief and its horizontal shortening, (b) the basement folding in the Duero and Madrid basins, (c) the development of the root of the mountain range, and (d) the depth of the lithosphere-asthenosphere border in the interior of Iberia. The deformations occurred through a large-scale folding and thickening mechanism, by the shortening of a lithosphere that was initially thinner, and with lateral contrasts in temperatures and composition.