The metamorphic-hosted siderite-Cu deposit of Frigido: structural setting and isotopic data

The Palaeozoic basement of Apuane Alps core complex hosts a variety of are deposits including the Cu-siderite deposit of Frigido, that was exploited until the 1960's, Mineralisation is represented by siderite veins, hosted by metamorphosed schist and ryolites. Sulphides associated with siderite are: pyrite, pyrrotite, chalcopyrite, galena and sulphosalts; quartz is the main gangue mineral. The siderite vein is emplaced along S2 foliation, and presents deformation textures, suggesting a synkinematic deposition. C-O isotope composition of siderite indicates a mineralising fluid equilibrated with basement rocks. The basement appear to be chemically heterogeneous but, at the same scale, isotopically homogeneous. Metamorphic (mineralising) fluids inherited their chemical composition in response to local scale features.