A detailed textural and geochemical study was carried out on a suite of anhydrous, spinel-bearing peridotitic xenoliths hosted in alkaline basic lavas from the Veneto Volcanic Province (VV P). Lherzolites and harzburgites show metasomatic textures superimposed on primary, protogranular textures. On the basis of textural relationships, relative modal percentages and grain size between primary and secondary parageneses, three metasomatic textures were distinguished: Type A characterized by reaction areas around orthopyroxene and spinel, generating olivine, clinopyroxene and spinel secondary crystals; Type B by the abundant presence of glassy patches closely intergrown with olivine, clinopyroxene, spinel and feldspar; and Type C by reaction areas around clinopyroxene, giving rise to spongy or completely recrystallized clinopyroxenes. Unmetasomatized lherzolites display flat REE patterns at about 2-3 x chondrite, while metasomatized lherzolites and harzburgites show a classic spoon-shaped ...
Metasomatism in the lithospheric mantle and its relationships to magmatism in the Veneto Volcanic Province, Italy
Bonadiman C.;Coltorti M.;Milani L.;Salvini L.;Siena F.;Tassinari R.
2001
Abstract
A detailed textural and geochemical study was carried out on a suite of anhydrous, spinel-bearing peridotitic xenoliths hosted in alkaline basic lavas from the Veneto Volcanic Province (VV P). Lherzolites and harzburgites show metasomatic textures superimposed on primary, protogranular textures. On the basis of textural relationships, relative modal percentages and grain size between primary and secondary parageneses, three metasomatic textures were distinguished: Type A characterized by reaction areas around orthopyroxene and spinel, generating olivine, clinopyroxene and spinel secondary crystals; Type B by the abundant presence of glassy patches closely intergrown with olivine, clinopyroxene, spinel and feldspar; and Type C by reaction areas around clinopyroxene, giving rise to spongy or completely recrystallized clinopyroxenes. Unmetasomatized lherzolites display flat REE patterns at about 2-3 x chondrite, while metasomatized lherzolites and harzburgites show a classic spoon-shaped ...I documenti in SFERA sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
