Estructura del sector norte de la Cuenca de Almazán (Cordillera Ibérica)

Abstract

The Tertiary compressional structure of the northern sector of the Almazan basin is defined by several E-W to NW-SE trending folds. These folds extend from the northern and eastern basin borders to the central part. Ceometrical reconstructions obtained from the study of seismic reflection profiles and outcrop observations indicate that the folds in the Paleogene beds can be followed to the Mesozoic strata below them and to the Palaeozoic basement. Their wavelength varies between 7 and 5 l<m, and their mean amplitude between 250 and 500 m. At surface most folds are asymmetric, the northern limbs of the anticlines reaching dips of 70-, whereas at depth they are gentler and more symmetric. Disharmonic folding is due to minor detachments in the upper part of the sections. Other structures present in the northern part of the Almazan basin are normal faults, unconformably covered by the Paleogene units, and related to Mesozoic extension giving rise to the Cameros basin