Genesis of polymetallic and precious-metal ores in the Western Mediterranean province (Cevennes, France-Sardinia, Italy)

Synopsis An attempt has been made at correlation between the Lower Palaeozoic Iglesi ente domain of southwest Sardinia and the southern Cevennes-Montagne Noire Variscan domain of France, with particular regard to the Cambrian-hosted ec onomic lead-zinc concentrations and the spatially associated precious-metal (Au) occurrences. Geological, lithogeochemical and lead isotope investigat ions led to the following conclusions. (1) The major lead-zinc deposits of Iglesiente and southern Montagne Noire have a Mississippi Valley-type origi n, which involved remobilization of pre-existing Cambrian syngenetic minera lization during the Ordovician distensive 'Sardic phase'. Lead isotope evid ence suggests mixed crustal sources for the Iglesiente lead. (2) The southe rn Cevennes stratiform Minerai Zero of the Malines district is not syngenet ic with the Cambrian host rocks. For this ore type a synto late-tectonic Va riscan formation model is proposed, similar to the model indicated for the genesis of the Salsigne gold deposit in the Montagne Noire. A re-evaluation of the Vigan gold occurrences, regionally associated with the Mineral Zero economic lead-zinc bodies, is therefore suggested. (3) The newly discovere d Tertiary epithermal gold province of Sardinia is genetically quite distin ct from the Palaeozoic lead-zinc province of Iglesiente.