Geochemistry of metabasites from the Nevado-Filabride complex, betic cordilleras, Spain: Relics of a dismembered ophiolitic sequence

Abstract

Major- and trace-element distribution, including REE data, in the metabasites of the Nevado-Filabride Complex (Betic Cordilleras, Spain) suggests that the whole mafic-ultramafic association represents a dismembered ophiolitic sequence. All the analyzed samples have been affected by sea-floor alteration. Yet only the fine-grained rocks have suffered some significant mobilization of the LREE. Life the other Western Mediterranean ophiolites, this sequence is related to the opening of the Liguro-Piemontese basin during Mesozoic times. However, the metabasites from Betic Cordilleras differ from the ophiolitic basalts by higher values of the more incompatible over less incompatible element ratios. The entire variation of these ratios in the Liguro-Piemontese basin is related to a dynamic melting process coupled with a diapiric uprise of the mantle source from the stability field of garnet peridotites. possibly up to the spinel-plagioclase facies transition. In this process, the ophiolites of the Betic Cordilleras would record the deepest stages and the lowest degrees of melting. This feature is related to the peculiar location of these ophiolites at the western end of the Liguro-Piemontese basin.