CONSTRAINS ON GEOCHEMISTRY OF ORE FORMING SOLUTIONS AT KORU PB-ZN DEPOSIT, CANAKKALE,TURKEY

The Koru ore deposits is part of the Serbo-Macedonian metallogenic belt that extends from Serbia through Greece and Bulgaria and into the Biga Peninsula which is situated 46 km North-East of Canakkale, Turkey. Oligocene rhyolitic volcanics consisting of porphyritic, locally massive, autobrecciated and flow-banded rhyolite lavas and domes host the mineralization of the Koru ore deposit. Ore minerals occur in veins ranging in width from few millimeters to about 3 centimeters. The dominant ore mineralogy includes pyrite, sphalerite, galena, hematite and minor amounts of chalcopryrite. The main gangue minerals are barite and quartz. 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 -51 to -44 within the pH range of 4 to 8.