Integrated gravity and topography analysis in analog models: Intraplate deformation in Iberia

Abstract

Trends in the topography of the Iberian Peninsula show a pronounced contrast. In the western part of the Iberian microplate the main topographic highs trend E-W to NE-SW and are periodically spaced with wavelengths of 250 km. Conversely, in the northeastern part, the region of the Iberian Chain, topography is more irregular and strike directions vary from NW-SE to E-W and NE-SW. We relate this phenomenon to shortening of a continental lithosphere, which contains two different, well-defined domains of lithospheric strength. Our hypothesis is supported by physical analog models. A new processing method has been developed to assist the interpretation of the model results. It utilizes spectral analysis of gravity and topography data derived from the experiments. Folding of the crust and mantle lithosphere yields periodic gravity fluctuations, while thickening processes lead to localized gravity lows. In this way gravity data can be used to distinguish between the two forms of lithosphere deformation and to correlate areas that underwent the same type of deformation. Gravity modeling has been performed under full in-depth control of the experimental lithosphere structure. As such, gravity signals from the models may be compared to field gravity data for better understanding the underlying deformation mechanism.