Petrology and geochemistry of granitic intrusions in the Viana do Castelo area, northern Portugal

Abstract

Granitic intrusions in the Viana do Castelo map-area in northern Portugal are part of the Hercynian plutonic belt of the Iberian peninsula. They consist predominantly of muscovite-biotite granite of varied textures with minor granodiorite and quartz monzonite. Chemically they exhibit typical calcalkalic differentiation trends and appear to represent a co-magmatic suite. They are peraluminous and show typical characteristics of S-type granites. An age of 316 ± 4 Ma was obtained from a Rb-Sr whole-rock isochron.