Relaciones entre la zonalidad petrológica y metalogénica de los macizos lerzolíticos de las cadenas alpinas del Mediterráneo Occidental (Cordillera Bético-Rifeña y Kabylias)

Abstract

Gamet-lherzolite facies, Ariegite and Seiland subfacies of the spinel-lherzolite facies and plagioclase-lherzolite facies have been identified in the Serranía de Ronda, Beni Bousera and Collo lherzolitic massifs. These petrological facies occur in a zonal arrangement: gamet lherzolite are in contact with the overlaying metapelitic sequence and spinel then plagioclase lherzolite occur inwards, representing the innermost zones in the former mantle body. The various occurrences of mineralizations can be classified in two main groups: one of them is essentialIy made up of chromite and Ni arsenides with pyroxene and/or cordierite as gangue minerals; the other consists Qf Fe-Ni-Cu sulfides and graphite, with pyroxene, plagioclase and phlogopite as gangue minerals. In both groups, the ores with the more refractory composition were the first to crystallize in the hotter core of the diapir while those other with a more differentiated composition were formed later within the external zones. The close correlation between petrological and metallogenical roning supports a magmatic origin of the mineralizations related to the petrologic evolution of the mantle bodies. The mineralizing liquids• originated from magmas generated by partial melting of the peridotites. The former migrated outwards, from the internal part of the bodies, during which marked interaction with the enclosing rocks and complex fractionation processes took place under moderate to low pressure conditions.