On the possible role of strike-slip related tectonics in the Ronda-Málaga area (southern Spain)

The Landsat Thematic Mapper (TM) image of the area between Ronda and Malaga in southern Spain reveals a number of northeast-southwest trending lineaments dissecting older and younger rock units. These lineaments are not represented in recent geologic maps of the area nor are they dealt with in the literature. Geomorphic evidence suggests that the lineaments are in fact the surface expression of major strike-slip faults running in the Iberian basement. This suggestion is supported by various types of geologic field data. The infill of the Ronda neogene basin located just north of Ronda demonstrates its orgin in wrenching tectonics. Furthermore, kinematic analysis of the Jurassic limestones of the Sierra Blanquilla block situated east of Ronda indicates fold rotation and a fault system that can be explained in a horizontal shear model. Further evidence for strike-slip deformation is found in the results of stress analysis using striated fault planes, yielding three successive stress tensors. Local field evidence shows that strike-slip deformation postdates the compressional and extensional phases of deformation. Absolute timing of strike-slip deformation is derived from subsidence analysis, restricting this tectonic period to late Langhian and Serravalian. A geodynamic cause for this strike-slip deformation is found when presenting the subsidence history of the Ronda-Málaga area within the context of western Mediterranean plate tectonics.