Abstract

This chapter presents a reconstruction of the geometry of the Guadalquivir Basin based upon the spatial position and morphology of isochronous surfaces defined by means of bio-events (i.e. discontinuities in the palaeontological record) apparent in the associations of calcareous plankton. It is possible to interpret the depositional history of the basin and to define five depositional sequences to correlate with cycles of global sea-level change.

Introduction

The Guadalquivir Basin is an ENE–WSW-elongated depression filled with Neogene sediments that crop out more than 800 m above sea level at the far eastern end. The topographic surface descends gradually to the west until it reaches the present coast of the Gulf of Cádiz. Sedimentation continues today below sea level in the Gulf of Cádiz.

The Guadalquivir basin separates an emergent foreland made up of Palaeozoic and Mesozoic rocks (the Variscian massif of the Spanish Meseta) to the North and the Betic Cordillera with Mesozoic and Cainozoic rocks to the South (Fig. 1). The Betic Cordillera (also referred to as the Betics) in the southern Iberian peninsula and the Rif in north Africa forms the westernmost major structure of Alpine age. The last Alpine deformation occurred during Serravallian and Early Tortonian times and several ‘postorogenic’ basins have developed under tectonic control of the major structural patterns of the Betics.