Geology, mineralogy and the Pb, S isotope study of the Kalkim Pb-Zn +/- Cu deposits, Biga Peninsula, NW Turkey

WOS: 000329991100004Three main Pb-Zn +/- Cu deposits (Handeresi, Bagirkacdere, and Firincikdere) occur south of Kalkim in the southeastern part of the Biga Peninsula (NW Turkey). Massive and disseminated Pb-Zn mineralization consists of ore veins in fault zones and replacement bodies in carbonate layers in metamorphic rocks. Garnet (similar to Ad(64)Gr(36)), pyroxene (similar to Di(30)Hd(45)Jo(25)), epidote and rare tremolite-actinolite are found as gangue minerals in ore zones. The garnets often show oscillatory zoning and correspond to grossular, andradite and grandite in composition. The pyroxene minerals are manganiferous hedenbergite, johannsenite and diopside. The Mn/Fe ratios of the pyroxene range between 0.3 and 0.9 (mean 0.5). Such compositions of the garnet and pyroxene and gangue assemblages are typical of distal Pb-Zn skarns. The ore minerals are pyrite, sphalerite, chalcopyrite, galena, magnetite, hematite, and arsenopyrite. The mean lead isotopic values for galena are Pb-206/Pb-204 similar to 18.760, Pb-207/Pb-204 similar to 15.689, and Pb-208/Pb-204 similar to 38.935. The comparison of these isotope data with the host-rock samples (graphite schist, andesite and granodiorite) indicates that part of lead could have been leached from the schists. The delta S-34(VCDT) values for galena, sphalerite, and chalcopyrite are -1.1 to + 1.5 % (mean: -0.2 %), 0.7 to + 2.1 % (mean: + 0.7 %), and -0.6 to + 1.5 % (mean: + 0.4 %), respectively. Lead isotope data and delta S-34(VCDT) values close to 0 % indicate the formation of ores by magmatic processes. Taken together, the Oligo-Miocene magmatism in the area is taken responsible for the polymetallic mineralization. However, the metamorphic rocks and their protoliths may have contributed part of the lead.Scientific Research Office of Ankara University (BAPRO) [06B4343007]This study is a part of the Ph.D. thesis of the first author at the Geological Department of Ankara University supervised by third author and also was supported by Scientific Research Office of Ankara University (BAPRO), Project No. 06B4343007. The authors would like to thank Taner Unlu for critical reading and comments of an early version of the article, Ilkay Kuscu for fruitful discussions in the field, Ahmet Cagatay for helping with the interpretation of polished sections, Jean S. Cline and Haroldo Lledo for sharing significant views and also allowing us to use the EPMA laboratory facilities, and Oreks Co. Ltd. for allowing access to the study area. We are also grateful the reviewers' (Jiri Zacharias and an anonymous reviewer), handling editor's (Miroslav Stemprok) and editor-in-chief's (Vojtech Janousek) valuable and helpful comments that improved the manuscript