Abstract
AbstractThe present-day topography in Iberia is related to geodynamic processes dealing with lithospheric-scale deformation. However, little attention has been paid to the role of inherited crustal- or lithospheric-scale structures involved in the recent observed large-scale topographic patterns. Whereas the analysis of brittle structures focuses on the evolution of Mesozoic sedimentary basins and their subsequent response to tectonic inversion, their contribution to mountain building has been underestimated. Large numbers of structures, from ductile to brittle, which affected the whole lithosphere, were developed during the evolution of the Cantabrian orocline (ca. 310–300 Ma). The contribution of these Paleozoic post-Variscan structures, together with lithospheric mantle evolution and replacement during orocline development in the Mesozoic and Cenozoic geological evolution of Iberia, remains unexplored. To explore the role of these inherited structures on the final configuration of topography during N-S Pyrenean shortening, we carried out a series of analogue experiments complemented by surface velocity field analyses. Our experiments indicate that strain was concentrated along preexisting crustal- to lithospheric-scale discontinuities, and they show several reactivation events marked by differences in the velocity vector field. Differences in fault displacement were also observed in the models depending upon preexisting fault trends. The obtained results may explain the different amount of displacement observed during the reactivation of some of the post-orocline structures in Iberia during the Cenozoic, indicating the key role of unveiled structures, which probably have accommodated most of the Alpine shortening.
Highlights
Since the advent of the Wilson cycle concept (Wilson, 1968), reactivation of previous structures represents one of the main controls in the tectonic evolution of continents
In order to understand the effects of the possible lateral strength variations caused by the putative differences in the post–Cantabrian orocline lithosphere underlying Iberia, we propose a kinematic model based on an integrated approach that combines analogue modeling, particle image velocimetry (PIV) analysis, and regional geology
The Mesozoic–Cenozoic tectonic evolution of Cantabrian orocline– related structures remains controversial and varies from east to west Iberia according to variations in lithospheric strength attributed to inheritance from the Mesozoic rifting episode together with changes in the mantle derived from orocline-triggered lithospheric delamination (Gutiérrez-Alonso et al, 2004)
Summary
Since the advent of the Wilson cycle concept (Wilson, 1968), reactivation of previous structures represents one of the main controls in the tectonic evolution of continents. Not much attention has been paid to the putative changes produced in the Iberian lithospheric mantle during orocline development (i.e., Gutiérrez-Alonso et al, 2011a, 2011b), and the meaning and origin of late orocline structures attributed to the tightening of the 180° bend that defines the Cantabrian orocline These structures, including faults observable at the present-day erosion level, controlled the basement structural grain in northern Iberia (Fig. 1A), and their imprint is noteworthy on the subsequent Mesozoic and Cenozoic belts and basins development, on the Alpine evolution of the northern and central Iberia mountain chains, and probably on the present-day relief of western continental Europe
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