UPLIFT AND EMPLACEMENT OF UPPER-MANTLE ROCKS IN THE WESTERN MEDITERRANEAN

The emplacement of mantle peridotites at crustal levels in southern Spain and northern Morocco has traditionally been explained by mantle diapirism in an area now occupied by the Alboran Sea. However, such models are inconsistent with many of the internal features of the Peridotite and cannot be related directly to the tectonics of the western Mediterranean. The structure and mineral chemistry of the Ronda peridotite combined with other geological and geophysical data indicate that the peridotite represents lithospheric mantle from the hanging wall of a Late Cretaceous to Paleogene zone of lithosphere-scale underthrusting (subduction), exhumed in the early Neogene in response to detachment of cold, gravitationally unstable lower lithosphere.