Studio mineralogico di un filone pegmatitico della Valchiavenna (SO)Mineralogical study of a pegmatitic dyke from Valchiavenna (SO)

This work consists of preliminary analyses of a Tertiary pegmatitic dyke from Valchiavenna (SO). Its purpose is to contribute to a research project about Tertiary pegmatites of the Central Alps. The pegmatitic dyke taken into account is situated in the western part of the Gruf Complex, which represents a deep Pennidic nappe included in the Lepontine Barrovian metamorphic dome, in the zone of the Alpine migmatization. The genesis of this pegmatite and of the nearby ones is related to the Oligocenic intrusion of the Bergell pluton, situated south-east of the Gruf’s migmatitic gneiss. The macroscopic analysis provided information about the structure of the champion and its relation with the surrounded body; the study of the mineralogical composition and the preliminary investigation into the microstructures have been realized by means of a microscopic analysis. Thereafter, backscatter images (BSE) revealed the presence of zircons that are useful for geochronological datings, which will be object of forthcoming studies