Zonas de falla y desarrollo de cataclasitas en la Unidad del Aljibe (Complejo del Surco de los Flyschs, Béticas)

Abstract

The Aljibe Unit is the largest tectonic element within the Flysch Trough Complex in the Betics. Its structure consists of an imbricate thrust system, developed on top of the Subbetic zone mainly during Middle Miocene. Strike-slip faults and normal-component faults developed at the same time and later. The study of representative deformation bands, a few to tens meters width and associated with all the type of faults, in terms of meso- and microstructures allow us to investigate the fault kinematics and conditions during deformation. In particular, the fault zones which affected the quartzose sandstones of the Aljibe Formation, show a high concentration ofbrittle deformation structures. Together with discrete fracture surfaces, joints and veins, and asymmetric folds, the more prominent structure corresponds to cataclastic slip bands (CSBs), 1 to 5 mm thick. They are either subparalell to the main fault surface or anastomosed. Fault rocks associated with CSBs are protocataclasites and cataclasites. Within the CSBs thicker than 2 mm, a cataclastic foliation oblique to CSB walls can develop. It provides a shear sense indicator coherent with other criteria observed in the same fault zone