Structure and palaeogeography of the External Betic Cordillera, southern Spain

Abstract

A structural interpretation of the External Betic Cordillera in the Granada-Jaén area of southern Spain is proposed based on the interpretation of seismic reflection profiles, subsurface well control and a balanced cross-section. Restoration of this balanced cross-section results in a new palaeogeographical interpretation for the area and a total estimated shortening of approximately 200 km. Traditionally, the Betic fold-thrust belt has been described as a series of north-vergent, imbricate thrust sheets, each having relatively little displacement (10–15 km). Restoration of this structural model to an undeformed state results in a Mesozoic palaeogeographical scenario of three carbonate platforms separated by two deep basins. An alternative interpretation is presented in this paper — that the structural style of the Granada-Jaén area is characterized by large displacement thrust faults. Restoration of the proposed cross-section leads to the palaeogeographical interpretation of a single Mesozoic basin. Along the transect of the cross-section this palaeo-basin is bounded to the north and south by platformal margins. The major implication of this study is that the palaeogeographical interpretation of a fold-thrust belt can be highly dependent on the structural interpretation.