THE MECINA EXTENSIONAL SYSTEM - ITS RELATION WITH THE POST-AQUITANIAN PIGGYBACK BASINS AND THE PALEOSTRESSES EVOLUTION (BETIC CORDILLERAS, SPAIN)

The Alboran Domain has undergone a west-southwestern-east-northeastern post-Aquitanian minimal extension of 104% in two stages. In the first one (Burdigalian-early Tortonian), the Mecina Extensional System was active, the Neogene Basins were piggy-back ones, and stress ellipsoids were oblate. In the second stage (Tortonian-Present), stress ellipsoids were prolate, and the original shape of the outcropping Neogene Basins was nearly the same as their present morphology. An orogenic wedge model is proposed in which the westward strain of the wedge has been produced by variations in the spreading rates of the Ligurian-Balearic and Tyrrhenian basin oceanic crusts.