The Massive Sulfide Deposit of Siirt Madenköy, South-Eastern Turkey

Abstract

The Siirt Madenköy massive sulfide ore deposit has been in operation since 2005. With its approx. 39 Mt reserves (2.40% Cu), it represents the largest Cu deposit and the largest mining operation in the country (1.5 Mt ore/year). The thickness of the adjacent rocks is composed of olivine-pyroxenite basalts pillow lava, which is spilite, interchangeable ore lenses of chalcopyrite and pyrite is about 170 m and reaches a depth of 350 m. The mid-Eocene aged porphyritic, strongly altered spilites are locally interspersed with diabase and covered by conglomerates. The ores appear massive, stock work and disseminated. Main ore minerals are idiomorphic pyrite, cataclastic chalcopyrite and fine-grained magnetite. The geochemical composition of the Cu ores of the Siirt-Madenköy deposit shows in places high levels of Cu, Fe and S, as important trace elements, As, Ba, Co and Ti are listed. In relation to Clarke values, Se, Bi, Cu, Mo and Co are strongly enriched, while Na, K and Ca as well as their coherent trace elements Rb, Sr and Cd are depleted due to hydrothermal alteration. The elemental distribution is characterized by log-normal distribution, proportionality effect, high Cu/Ni ratio and significantly positive correlation between the element pairs MgO-Ni, Cr-Ni and Co/FeO-Co. The dependence of Cu and SO 3 contents and Cu/FeO, SO 3 /FeO ratios are to be interpreted as an indication of the common origin of Cu, Fe and S. In general, Cu, Zn, Pb and S content decrease with depth, whereas those of Fe 3 O 4 increase. The variograms of the ore distributions are characterized by hole effect, trend and zonal anisotropy, which reflect alternation of ores with host rocks and changes in elemental contents. The Siirt Madenköy deposit is attributable to Cu and Zn ratios of the Cu class of ophiolitic massive sulfide deposits. Due to the very high Cu/Pb and Cu/Zn ratios, it can be described as an analogous deposit of the mid oceanic ridge, for example comparable to ores of Galapagos Ridge. The