Andradite From Pb-Zn Djurkovo Deposit, Central Rhodopes: Chemical Composition And U/Pb Dating

Recent advances in the U/Pb techniques revealed that the garnets from the grossular-andradite series are suitable for age determination due to the isomorphic incorporation of REE and U in the garnet structure (Seman et al., 2017; Salnikova et al., 2019). The occurrence of Ca-garnets is generally connected with skarn formation, resulting from the interaction of silicate melts and high-temperature hydrothermal fluids with carbonate host rocks. Consisting of calc-silicates, skarns commonly host economic Fe, Cu, Zn-Pb-Ag, Au, Sn, W or Mo mineralization (Meinert et al., 2005). The timing of formation of the skarn ore deposits often corresponds to the age of the related magmatism. In cases of distal ore deposits (such as Pb-Zn deposits in the Central Rhodopes), with uncertain genetic connection with possible source, the indirect timing could be acquired by postmagmatic (hydrothermal) minerals. In attempt to determine the age of ore formation in Bulgarian deposits, we have studied garnets from several localities. Here we present the mineralogical and geochemical characteristics of two types of andradite garnets from Djurkovo deposit, Laki region.