Lead and sulfur isotope constraints on the genesis of the polymetallic mineralization at Oued Maden, Jebel Hallouf and Fedj Hassene carbonate-hosted Pb–Zn (As–Cu–Hg–Sb) deposits, Northern Tunisia

• Oued Maden, Jebel Hallouf and Fedj Hassene deposits are located in Northern Tunisia.
• Polymetallic mineralization is hosted by Upper Cretaceous limestones.
• The sulfur is derived through thermochemical and/or bacterial reduction of sulfate.
• The lead in galena has been derived from a crustal source during Upper Miocene time.

The Oued Maden, Jebel Hallouf and Fedj Hassene Pb–Zn (Ba–Sr–F–Fe–Hg) hydrothermal ore deposits are located in the Nappe zone of Northern Tunisia. These ore deposits occur as epigenetic veins, karst and stockwork fillings in Upper Cretaceous limestones. The ore mineralogy consists mainly of galena and sphalerite, accompanied by minor amounts of jordanite, pyrite, chalcopyrite, orpiment, realgar, and other sulfosalts. Sulfur isotope data from sphalerite and galena indicate that the reduced sulfur was derived through thermochemical and/or bacterial reduction of dissolved sulfate resulting in metal precipitation. Lead isotope ratios and corresponding calculated age models indicate that the Pb in galenas has been derived from a homogenous crustal source during Upper Miocene time.