Analisi strutturale della deformazione alpina nei granitoidi dei Tauri nell'area delle Mesule (Alto Adige-Südtirol, Italia): interazione fra deformazione fragile e duttile durante condizioni metamorfiche in facies anfibolitica

The aim of the present work is the study of the Alpine deformation in the area of the Mesuler glacier, near the Neves Lake, in Alto Adige –Südtirol (Italy). In the Neves area the deformation is localized within metagranitoids belonging to the Zentralgneiss Penninic unit of the Tauern Window; the pre-Alpine granitoids were deformed during the Alpine orogeny under amphibolites facies metamorphic conditions, and were converted to orthogneiss and mylonites. Specific objectives of the thesis are: i) the study of the interaction between ductile and brittle deformation during the high-grade metamorphic conditions, with a particular focus on the development of quartz veins during a prevailing ductile deformation; ii) the organization of a database and analysis in a GIS environment of the bulk structural data collected in numerous previous investigations of the area. With regard to the quartz veins, it was performed an analysis of different types of geometries and their kinematic relationships associated with ductile structures. Unfortunately a preliminary attempt at reconstructing 3D geometry of the veins by Ground Penetrating Radar (GPR) failed. We also analyzed the field geometry of veins in terms of the kinematics of vein opening and cycles of fluid pressure during ongoing deformation. The fluid-rock interaction during vein formation was investigated by the analysis of thin sections of the alteration haloes surrounding the veins and by geochemical analysis of the altered zones. Some quartz veins were used for the study of fluid inclusions to constrain the conditions of formation.