Fold and fault interactions during the development of an elongated narrow basin: The Almanzora Neogene-Quaternary Corridor (SE Betic Cordillera, Spain)

Abstract

Elongated corridors grow in different tectonic settings, mainly in areas deformed by fold and fault sets parallel to the borders. The Almanzora Corridor, however, is a good example of an E-W elongated asymmetrical narrow basin developed in a changing stress scenario, generated by the interaction of fold and fault sets oriented parallel and oblique to the corridor borders. The initial crustal thickening process was mainly related to the development of the E-W oriented Sierra de Los Filabres large antiform, which constitutes a major heterogeneity. During the Tortonian, a NW-SE convergent tectonic setting, oblique to this already emerged antiform, gives rise to a large dextral simple shear band that determines: the development of a major fold (Las Estancias antiform), the asymmetrical location of minor tectonic structures (faults and minor folds), and the distribution of sedimentation/denudation areas that finally configure the Almanzora Corridor synform. Furthermore, development of NW-SE oriented normal faults points to NE-SW orthogonal extension in a new stress field oblique to the corridor borders. This region illustrates that the elongated character of the corridors may persist, inherited from the orientation of previous crustal rheological heterogeneities. In addition, marine transgression may be produced in compressional settings, favored by the synform development during initial stages of crustal thickening, finally led to the relief uplift. Copyright 2007 by the American Geophysical Union.