GEOCHEMISTRY OF DISSEMINATED ORE MINERALIZATION AT KORU PB-ZN DEPOSITS IN CANAKKALE,TURKEY

The Koru ore lead-zinc deposits is part of Serbo-Macedonian metallogenic belt which is situated 46 km North-East of Canakkale, Turkey. Geologic history of sphalerite and galena vein deposits is complicated. Initially, disseminated ore has been brought up to near surface by Tertiary volcanic rocks. This was followed by dissolution and precipitation of sphalerite and galena by sulfur and chloride-bearing hydrothermal solutions. The dominant ore mineralogy includes pyrite, sphalerite, galena, hematite and minor amounts of chalcopryrite. The main gangue minerals are barite and quartz. We have used the MELTS algorithm to confirm that ore-bearing volcanic rocks are genetically related to each other. Fluid inclusions in sphalerite give a temperature range of 120-160 ⁰C. Using SUPCRT software we established log fO₂-pH diagram at 150 ⁰C and ∑S= 10^-3 for the H-S-O system and superimposed stability limits of galena, sphalerite, magnetite, hematite and barite. Stability field of ore and gangue minerals indicate that ore forming solutions straddle the HS^- and SO₄^-2 fields indicating fO₂ fluctuated between reduced and oxidized conditions from -55 to -45 within the pH range of 5 to 9.