Estructura cortical de la cordillera y margen continental cantábricos: perfiles ESCI-N

Abstract

The aim of this study is the N-S crustal structure of the Cantabrian Mountains and the North Iberian margin along a transect close to the 5°W meridian. The geological transect is based on all geological and geophysical data available, especially the onshore and offshore deep seismic reflection profiles ESCIN-2 and ESCIN-4. The structure of the orogen results from the superposition of the Alpine deformation, related to the partial closure of the Bay of Biscay during the Tertiary, on the Variscan crust. The N-S structure is that of an orogenic prism, with opposite vergences at both ends where two foreland basins developed: the Duero Basin in the S and the North Iberian platform basin in the N. The lower crust from the North Iberian margin slided southwards along a detachment and indented between the upper and middle Iberian crust. This forced the delamination and northwards underthusting of the middle and lower Iberian crust. As a result, the crust thickened under the Cantabrian Mountains and a 55 km thick crustal root developed. Simultaneously, the Cantabrian Mountains were uplifted by several north vergent crustal thrusts rooted at 14-15 km deep. Shortening of the margin during the Tertiary has been estimated in 96 km.