Genesis of polymetallic and precious-metal ores in the Western Mediterranean province (Cévennes,France

Abstract

An attempt has been made at correlation between the Lower Palaeozoic Iglesiente domain of southwest Sardinia and the southern Cévennes-Montagne Noire Variscan domain of France, with particular regard to the Cambrian-hosted economic lead-zinc concentrations and the spatially associated precious-metal (Au) occurrences. Geological, lithogeochemical and lead isotope investigations led to the following conclusions. (1) The major lead-zinc deposits of Iglesiente and southern Montagne Noire have a Mississippi Valley-type origin, which involved remobilization of pre-existing Cambrian syngenetic mineralization during the Ordovician distensive ‘Sardic phase'. Lead isotope evidence suggests mixed crustal sources for the Iglesiente lead. (2) The southern Cévennes stratiform Minerai Zéro of the Malines district is not syngenetic with the Cambrian host rocks. For this ore type a synto late-tectonic Variscan formation model is proposed, similar to the model indicated for the genesis of the Salsigne gold deposit in the Montagne Noire. A reevaluation of the Vigan gold occurrences, regionally associated with the Minerai Zéro economic lead-zinc bodies, is therefore suggested. (3) The newly discovered Tertiary epithermal gold province of Sardinia is genetically quite distinct from the Palaeozoic lead-zinc province of Iglesiente.

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

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