The Ushkatyn-III deposit is located in Central Kazakhstan, 300 km west of Karaganda. It is ascribed to the weakly metamorphosed Atasu-type hydrothermal–sedimentary ore deposits. The Upper Devonian (D₃fm₂) carbonate sequence of this deposit comprises stratiform barite–lead, iron, and manganese orebodies. The study was focused on the iron– and manganese–bearing deposits. New data were obtained on the content of major (Si, Ti, Al, Fe, Mn, Mg, Ca, Na, K, P), trace (Li, Be, Sc, V, Cr, Co, Ni, Cu, Zn, Ga, Ge, As, Rb, Sr, Y, Zr, Nb, Mo, Cd, Sn, Sb, Cs, Ba, Hf, W, Tl, Pb, Th, and U), and rare-earth elements (REE) in all rocks of the ore-bearing unit. It is shown that all rocks, including host limestones, are enriched in Mn, As, Zn, Ba, and Pb, while normalization to aluminum revealed excessive Li, Be, Sr, Y, Mo, Cd, Sb, W, and Tl contents relative to the terrigenous part of sediment. REE variations point to a change of redox settings for accumulation of initial metalliferous sediments. Geological and geochemical data show that the genesis of the barite–lead, iron and manganese ores is related to the evolution of a single hydrothermal system. The ores were formed near or on the seafloor surface: the barite–lead ores are confined to venting sites on reefal buildups, while iron and manganese ores are formed from matter dispersed in the water column at some distance from hydrothermal vents.