Características petrológicas y edad K-Ar de las sienitas-nefelínicas del Morro del Recogedero (Fuerteventura,Islas Canarias)

Abstract

The nepheline syenites from the Morro del Recogedero outcrop represent the fractionated end member of the alkaline gabbro-ijolite associated rocks. Two K-Ar ages for the nepheline syenite rocks have been obtained. One of them (25 Ma.) corresponds to the magmatic crystallization age whereas the other (21.6 Ma.) is interpreted as a thermal resseting age. The latter is due to a thermal metamorphism produced by piroxenite-gabbro intrusive pluton, which has been dated indirectly. The nepheline syenite crystallization age is in the range of the ultra-alkaline Miocene serie, the oldest intrusion of the Basal Complex