Small metagabbro bodies are enclosed in the metasedimentary sequence of NW Sardinia. The metagabbro represents the last magmatic episode before the continent-continent collision which built up the Variscan chain of north Sardinia. The metagabbro are composed up of variable proportions of plagioclase and pyroxene igneous relics and metamorphic minerals. Major and trace element data, i.e high TiO2, P2O5 and low K, Rb content, as well as LREE, Nb, Ta enrichment, suggest an alkaline affinity for the gabbro and emplacement in a within-plate tectonic setting. The gabbro was derived from an island alkali basalt-like asthenospheric mantle source enriched with incompatible elements and uncontaminated by crustal or subducted materials. Non-modal modelling indicated a 5-7% partial melting of the asthenospheric mantle.
Pre-Variscan metagabbro from NW Sardinia, Italy: evidence of an enriched asthenospheric mantle source for continental alkali basalts
FRANCESCHELLI, MARCELLO;CRUCIANI, GABRIELE;
2003-01-01
Abstract
Small metagabbro bodies are enclosed in the metasedimentary sequence of NW Sardinia. The metagabbro represents the last magmatic episode before the continent-continent collision which built up the Variscan chain of north Sardinia. The metagabbro are composed up of variable proportions of plagioclase and pyroxene igneous relics and metamorphic minerals. Major and trace element data, i.e high TiO2, P2O5 and low K, Rb content, as well as LREE, Nb, Ta enrichment, suggest an alkaline affinity for the gabbro and emplacement in a within-plate tectonic setting. The gabbro was derived from an island alkali basalt-like asthenospheric mantle source enriched with incompatible elements and uncontaminated by crustal or subducted materials. Non-modal modelling indicated a 5-7% partial melting of the asthenospheric mantle.
I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
