The gold mineralization of Baccu Locci (Sardinia, Italy): origin, evolution and concentration processes |
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| Authors: | F Bakos G Carcangiut S Faddat A Mazzella R Valera |
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| Institution: | Agip Miniere S.p.A., V.le Brenta 29, 20139 Milano (Italy);Centro Studi Geominerari e Mineralurgici del C.N.R.;Istituto di Giacimenti Minerari, Geofisica e Scienze Geologiche, Piazza D'Armi, 09123 Cagliari (Italy) |
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| Abstract: | As-Fe-Cu-Pb-Zn-Ag-Sb sulphides and sulphosalts, with native gold as a frequent accessory (locally concentrated with high values) are the ore minerals of a deposit occurring in a Silurian volcanosedimentary sequence, either as concordant bedded orebodies, or as discordant veins and split fillings at the contact between shales and lamprophyres of the late Hercynian magmatism. Scheelite, mainly bound to acid metavolcanics, is occasionally scattered as isolated grains in the sulphides. The local geological setting together with correlations with other deposits occurring along the same regionally distributed Lower Paleozoic sequence, permit the proposal of the following scheme for the origin and evolution of the Baccu Locci Au-bearing mineral deposit: (1) Base-metal sulphide deposition, with gold, in the Silurian volcanosedimentary sequence: protore. (2) Hercynian tectonometamorphic activity, accompanied by multiphase ore mobilization and concentration processes, stratabound. (3) Hercynian magmatism, locally represented by lamprophyre dikes and by the effects of multiphase hydrothermal activity: ore mobilization and redeposition. |
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