Combined lead, sulphur and oxygen isotopes have been analysed in ore (galena and sphalerite) and
associated (quartz, barite) minerals from the Mazarambroz Pb-Zn mineralization. Lead isotopic model ages
in galenas cluster around 121 ± 8 Ma in good agreement with previously suggested mesozoic age of this
Pb-Zn mineralization estimated by apatite fission tracks in mylonitic wall-rocks. Isotopic composition of
Mazarambroz mineralization suggests a high rock (metamorphic/granitic)/fluid interaction with minor
participation of meteoric waters. These fluids circulated deeply along fragile cracks of the major shear zone
of Toledo