Geological, geochemical and fluid inclusion investigations on the Duna Pb-Ba-(Ag) deposit, Central Alborz, North Central Iran

The Duna Pb-Ba-(Ag) mine is located ca. 155 km north of Tehran in the central Alborz structural zone, northern Iran. ore mineralization occurs as stratabound, epigenetic, E-W and WSWENE trending veins veinlets fracture-controlled well massive open-space filling textures within a Permian dolomitic limestone host rock. Field observations mineralogical petrographic studies show dolomitization, silicification possibly haematisation In galena barite are main minerals, followed by pyrite, quartz, chalcopyrite, tetrahedrite, sphalerite, calcite supergene minerals such covellite, malachite, azurite, cerussite, anglesite, Fe-oxides. chemical analyses highgrade samples an average grade 18.66 wt. % for Pb, 19.99 Ba, 120 ppm Ag together with substantial quantities Zn (0.15 %), As (690 ppm), Cu (0.86 Sb (0.25 Sr (0.56 %). amount silver some from tunnel discordant layers up to 7030 ppm. positive Eu/Eu⃰ ratio weak negative Ce/Ce⃰ anomaly were most likely inherited magmatic water. presence pyrite chalcopyrite co-precipitation sphalerite suggest high-temperature mineralizing fluids. homogenization temperatures fluid inclusions concordant span between 135 165 ºC salinities 18.54 23.65 NaCl equivalent, while 113 285 7.34 equivalent. structural, geological, geochemical, paragenesis inclusion data allow consideration two stage scenario; 1st /older/MVT-type (Early Cimmerian tectonic phase), second stage/younger/Irish-type (Laramide orogenic movements). data, high temperature inclusions, content, especially layers, indicate involvement water mixed meteoric connate fluids comparable Irishtype stage, which formed along brecciated zones thrust faults. was influenced Akapol granitoid intrusive mass, overprinted stage/older/MVT-type.