Source of lead in base- and precious-metal deposits and their volcanic host-rocks from the tertiary epithermal district of W-Sardinia

Lead isotope analyses have been performed on sulphides and host-rock samples form the Tertiary auriferous and base-metal epithermal system of W Sardinia. No lead-isotopic evidence of any filiation or mixing phenomena between the Tertiary district and the nearly Cambrian metallogenic province (Iglesiente) has been detected. Lead in Tertiary base-metal and precious ores is interpreted to be derived from mixing processes between a mantle-derived component and a crustal end-member shown to imprint the Pb isotopic compositions of the studies volcanic rocks. (authors). 13 refs., 3 Figs., 1 tab