Petrología y mineralogía de los xenolitos mantélicos del volcán la Banya del Boc (Girona)

Abstract

Type I mantle xenoliths enclosed in alkaline mafic lavas and pyroclastic materials from La Banya del Boc volcano are studied in order to assess the nature of the subcontinental lithospheric mantle in the Catalan area. Anhydrous spinel lherzolites and harzburgites are the dominant lithologies, but pyroxenites are also found. Amphibole as accessory mineral is occasionally observed in peridotites. Protogranular is the most characteristic texture, but peridotites also show porphyroclastic and equigranular textures. All major mineral and spinel compositions indicate depletion by partial melting in peridotites, but metasomatism is also inferred. Decreasing of jadeite component in clinopyroxene with the degree of melting suggests that this could be related to decompression and upwelling of the mantle. The pyroxenites do not follow the melting trend