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

The emplacement of mantle peridotites at crustal levels in southern Sp ain and northern Morocco has traditionally been explained by mantle di apirism in an area now occupied by the Alboran Sea. However, such mode ls are inconsistent with many of the internal features of the Peridoti te and cannot be related directly to the tectonics of the western Medi terranean. 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 o f cold, gravitationally unstable lower lithosphere.