Petrogenesis of the mafic igneous rocks of the Betic Cordilleras: A field,petrological and geochemical study

Mafic igneous rocks are widespread in the Nevado-Filabride Complex. the low ermost metamorphic unit of the internal zones of the Betic Cordilleras. The y form intrusive, small, discontinuous bodies, predominantly dikes with sub ordinate small lava flows. The entire complex underwent alpine compressiona l metamorphism during the Paleogene continental collision, resulting in ecl ogites and blueschists in the mafic bodies and high-pressure assemblages in the intruded metasediments. Locally, weakly metamorphosed or completely un metamorphosed igneous rocks with the same textural features occur as patche s surrounded by eclogitized igneous rocks. The bulk rock chemistry of unmet amorphosed and completely metamorphosed mafic igneous rocks is consistent w ith an alkaline to transitional tholeiitic magmatism with typical within-pl ate geochemical characteristics. All but a few samples are nepheline normat ive and display REE and trace element characteristics typical of continenta l, rift-related magmatism. This conclusion is strongly supported by the min eral chemistry of the major constituents, in particular the calcic Ti-rich character of clinopyroxene, the lack of orthopyroxene, and the occurrence o f kaersutitic amphibole. incompatible trace element abundances and Sr and N d isotopes support the provenance of these magmas from a variably metasomat ized previously depleted sub-continental lithospheric mantle source.