Angara-Ilim iron-ore basin

ANGARA-ILIM IRON-ORE BASIN (RU: Ангаро-Илимский железорудный бассейн) is situated within the Irkutsk province of RSFSR, between the Angara and Ilim rivers. The deposits (Korshunovskoe and Rudnogorskoe), which are developed within this basin, are located at 430 and 520 kilometres to the north of Irkutsk city, at the Tayshet-Lena railway. Within the limits of the basin, there have been explored or evaluated also the Octyabrskoe, Krasnoyarovskoe, and Sedanovskoe deposits within the Angara-Chunsky region, Tatyaninskoe and Koltsevoe deposits within the Angara-Ilim region.

All deposits and ore manifestations are situated at the south-eastern periphery of the Siberian platform, and are associated with the sedimentary rocks (dolomites, limestones, marls, mudstones, sandstones) of Cambrian and Ordovician, and with the traps of the Permian-Triassic. The ore depositions are enclosed within the steeply dipping structures of the tubular shape, which are coming out onto the surface. Besides the tubular ore bodies, there have been uncovered at the certain deposits the tabular ore depositions, which are outgoing from these deposits. The major ore-forming minerals are magnetite, less often hematite and martite, rarely pyrite and chalcopyrite. The textures of the ores are brecciated, interspersed, and reticulate-veined.

During the processes of the formation of the deposits, they distinguish the skarn-ore, hydrothermal, and supergene stages. The balance reserves of the iron ores (of the A+B+C1+C2 categories) of the Korshunovskoe deposit are 252 million tonnes (1981) down to the average depth of 500 metres, and with 29.3% average content of Fe, of the Rudnogorskoe deposit are 268 million tonnes, down to the depth of 600 metres, and with 43.3% content of Fe. The total forecasted reserves of the magnetite ores of the remaining deposits are approximately 2 billion tonnes down to the depth of 600-1200 metres, with 26-35% average content of Fe. Besides this, there are within the basin many ore manifestations, which have not been evaluated. The Korshunovskoe (1965) and Rudnogorskoe (1981) deposits are developed by the Korshunovskiy mining-beneficiation combined enterprise.