The Zafarraya Polje (Betic Cordillera, Granada, Spain), a basin open by lateral displacement and bending

Abstract

The Zafarraya Polje is situated in the Subbetic (Betic External Zone), near the contact with the Betic Internal Zone. This is a small tectonic basin delimited by faults of which the main component is normal, but located among folds and reverse and dextral-reverse faults formed in a compressive context. One N–S fault marks the western border of the basin and shows major dextral displacements in its southern part (at the SW of the basin but directly outside the basin) and major normal movements in the northern part (on the west side of the basin). This fault took on great importance in the formation of the basin, and its movements are not compatible with the stress ellipsoids existing during the Neotectonic period. The basin appeared just at the end of the formation process of the compressive structures, probably at the beginning of the late Tortonian, as the result of the westward push of the Internal Zone in the southernmost part of the Subbetic in this area. This resulted in an intense local compression on the present southern border of the basin, causing a southward bending of this border and the dextral displacements of the N–S fault. Simultaneously, this movement created tension in the interior of the basin, forming different normal faults within the basin. The whole structure constitutes a basin formed by lateral displacement and bending. Nevertheless, the sinking process of the basin has continued until the present owing to the later radial extension in the region.