Excursion D - The Neogene of the Western Guadalquivir Basin (SW Spain)

Abstract

The Guadalquivir Basin is an important depression, elongated in the ENE-WSW direction, which is almost entirely made up of soft sediments. Starting at the eastern end it has an altitude of more than 800 m above sea level, descending gradually to the West, reaching the coast in the provinces of Huelva and Cadiz. Sedimentation continues today below sea level in the Gulf of Cadiz. Traditionally the Betic orogene has been divided by spanish Geologists into 3 regions, according to the different paleogeographic characteristics during deposition (Fig. 11). The Betic sensu stricto consists of Paleozoic and Triassic rocks that form the "internal zones". The Subbetic is the thrust belt formed by allochthonous, mainly deep pelagic sediments of the Mesozoic and Cenozoic, accumulated in the Basin, whereas the Prebetic constituted the northern passive margin, covered by shallower shelf sediments.