COPPER MINERALIZATION IN ZHEZKAZGHAN ORE FIELD, CENTRAL KAZAKHSTAN: INSIGHTS INTO ORE-GENESIS AND STRUCTURALLY CONTROLLED MINERALIZATION SYSTEM

The world-class Zhezkazghan Ore Field is a prominent Sedimentary-Hosted Stratabound Copper (SSC-type) mineralization system located in the northern Chu Sarysu basin (Central Kazakhstan). These copper deposits occur within an Upper Carboniferous (Pennsylvanian) fluvial clastic red bed sequence. The mineralization system shows two significant zones of chalcopyrite-dominated and bornite-dominated assemblages with minor chalcocite, digenite, covellite, and djurleite. Pyrite in both assemblages occurs in the form of framboidal pyrite and relict pyrite, showing the early stage of mineralization and being replaced by bornite in the late stage of mineralization. The petrographic evidence at the Zhezkazghan deposits includes the presence of copper sulfides as intergranular cement. Saryoba East deposit, part of Zhilandy Group deposits in the northern Zhezkazghan deposit, shows the occurrence of sulfides as clasts and within/along the calcite veins in addition to sulfide replacement. Known mineralization at deposit sites in the Zhezkazghan Ore Field is structurally controlled at the intersection of syn-depositional folding F1 anticlines (E-NE-trending) crossed by F2 anticlines (N-NW-trending). The structure can be likened to the egg-carton model, facilitating the movement of dense ore brines through the petroleum-bearing anticlines. This interaction leads to the formation of copper sulfides at the points where these fluids are mixed.