Tectonics units of central Sardinia: s tructural evolution and related ores

Many studies consider the Variscides of Sardinia as the result of the Lower Carboniferous amalgamation between the north Gondwana margin and the ribbon of Gondwana-detached terranes. The orogenic wedge in Sardinia is best preserved in the Nappe zone, where a huge stack of tectonic units, is well exposed from NW to SE. Though this zone was satisfactory outlined under stratigraphic and structural point of view, several questions still remain open for the lack of basic modern geological maps and for the lack of geochronological data on the sequences of some tectonic units (Barbagia Units) where the metamorphism erases any fossil record. Bridging this gap made necessary undertaking the detailed mapping of the nappe zone in the southern slope of the Gennargentu using new tools, such as gamma ray portable spectrometry, able to discrimate undistinguishable units on geochemical base. In this way a new vast area was mapped.The study and dating of detrital zircons was performed on some metamorphic units. In this way a maximum age to the Barbagia Units was assigned and the formations of the Meana Sardo unit were discriminated. The provenance of the clastic component was located in the cratonic areas facing the Galatian Terrenes. These results allowed defining the structural frame and evolution of this sector of chain. Moreover he new knowledge on the structural, stratigraphic and geochronological scenario allowed a new hypothesis on the genesis of the ore deposits.