Zn-Pb mantos and veins at Domo de Yauli, Central Peru: two products of one hydrothermal system with common Pb & S sources, but contrasting fluid inclusion characteristics.

Lead and sulphur isotopes reveal that Zn-Pb veins and mantos at Domo de Yauli were formed by the same hydrothermal systems. Miocene intrusions are the predominant source of lead and other metals. Sulphur is also of magmatic origin with a local input from sedimentary sulphate. Based on contrasting fluid inclusion data, it is concluded that the veins hosted by silicate rocks were formed during cooling, dilution and CO₂-degassing of a moderately saline fluid. By contrast, ore in the mantos was precipitated due to the pH increase during interaction of the hydrothermal fluid with the carbonate host rocks. The fluid inclusion data indicate either mixing with another fluid (basinal brine or magmatic fluid) or intermittent boiling in the mantos.