Magmatism and hydrothermal processes in the Funtana Raminosa ore district (Central Sardinia, Italy): petrographic and geochemical features

A petrographic and geochemical study, centered on the numerous subvolcanic bodies cropping out as stocks, sills and dykes in the Funtana Raminosa ore field, is reported. Particular attention has been devoted to the widespread hydrothermal alteration phenomena involving such magmatites. The research has allowed us to recognize magmatic typologies, from andesites s.l. to dacites and rhyolites, likely connected with the Hercynian post-orogenic volcanism. The imprint of different types of hydrothermal alteration processes on these rocks and their temporal succession have been reconstructed. In addition, the results as a whole have allowed us to determine the intrusive sequence of the different magmatic products and their different styles of intrusion, which require a coupled structural evolution of the area. Finally, as regards a possible link between magmatism and mineralization, the study indicates that conditions suitable to ore deposition were limited to the first magmatic phase characterized by andesitic s.l. products.