Heterogeneidade composicional dos ciques máficos subvulcânicos, tardi a pós-variscos do norte de Portugal (Zona Centro Ibérica)

ABSTRACT: This study is dedicated to the presentation and interpretation of whole-rock geochemical data concerning a few mafic subvolcanic dykes located in northern Portugal, related to the late to posttectonic stages of the Variscan orogeny. Overall, the analyzed rocks are reasonably fresh, ultrabasic to intermediate, metaluminous to moderately peraluminous, and calc-alkaline or alkaline. There is no evidence implying the occurrence of crustal contamination, but crystal fractionation is likely to have played either a minor or more meaningful role on the petrogenetic evolution. While most dykes were probably generated from subduction-modified, metasomatically-enriched lithospheric sources, others possibly derived from the asthenosphere. There are also important differences regarding the residual mineralogy of the sources, as well as the melting degrees.