Abstract

The major structures of the Iberian margin of the Ebro basin are described, and their regional kinematics are discussed. Two types of alluvial fan system are distinguished. The paleogeographic and tectonic evolution of the margin is analysed in terms of the eight tecto-sedimentary units defined in the previous chapter. Rates of sedimentation averaging 10 cm/1000 years for the Paleogene dropped to 7 cm/1000 years for the Neogene.

Introduction

The sedimentation of the Tertiary of the Iberian margin of the Ebro basin was mainly controlled by tectonic activity. Tectonic activity controlled the horizontal and vertical evolution of the sedimentary fill (see Chapter E5), the geographic location and orientation of the thresholds and the depositional areas, the extent and relief of the source areas, and also certain aspects of the facies of the deposits.

Because of the controlling importance of tectonic activity, we start this chapter with an outline of the main tectonic structures that were active under general tectonic compression throughout the Tertiary. Some of these structures probably originated as strikeslip faults during the Late Paleozoic, and then controlled the Mesozoic sedimentary history of the Iberian Range (Alvaro et al., 1979).

We first describe the most important structures (Fig. 1).

In the western sector, to the NW of the Queiles river, the major structures (Muñoz, 1992) are the thrust front of the Sierra de Cameros–Demanda, the NE–SW prolongation of the Odemira–Avila basement-cutting fault, and the Arnedo, Baños de Río Tobía and Najera monoclinal folds.