Caracterización geoquímica y estudio comparativo de plagiogranitos de las Zonas Surportuguesa y Ossa-Morena (SO del Macizo Ibérico, España)

Abstract

Plagiogranites and albitic rocks belonging to contrasted magmatic associations of different ages and geodynamic environments outcrop in Ossa-Morena (OMZ) and Surportuguese (SPZ) Zones. OMZ plagiogranites are related with Cambrian-Ordovician rifting and represent a part of the felsic members of a bimodal magmatic suite and show oceanic plagiogranites affinities. SPZ plagiogranites are related with a Carboniferous volcano-plutonic calc-alkaline suite related with Variscan Orogeny. Both plagiogranites show many similar petrological and geochemical characteristics but display some different immobile elements ratios as La/Nb, Th/Nb, Th/La that are unaltered by metamorphism, magmatic differentiation and alteration processes and prove differences in their sources. SPZ plagiogranites show a more compositional homogeneity than OMZ ones. This is interpreted as a proof of cogenetic origin for SPZ plagiogranites and heterogeneous origin for OMZ plagiogranites, derived from the mix of different sources (astenospheric, lithospheric and crustal).