Дундговь болон Хэрлэнгийн төмрийн металлогений бүсэд тархсан төмрийн ордууд

Abstract

Iron Oxide Apatite and Iron Oxide Copper Gold deposits generally consist of Fe and Cu-Au ore, and some deposits occasionally are recognized P, REE, Co, Ag and U. IOCG deposits are divided into magnetite and hematite subtypes by general ore mineral. Magnetite type IOCG has Na-Ca or, Na and potassic alteration zones, ore bodies are breccia and veins in shapes, ore-forming fluid was δ18O light supplied by magmatic and metamorphic waters. Hematite IOCG has a little potassic alteration zone, and ore bodies are formed breccia and lens in shapes in sericitic-chloritic alteration zone. Ore-forming fluid was δ18O heavy supplied by magma with a significant contribution of meteoric water. Banded Iron Formation is divided into Algoma, Superior and Rapitan sub types. The Algoma type BIF has δ18O of primary silica changed from +8‰ to +20‰ at temperatures below 100°C during diagenesis, indicating that although O isotope exchange occurs during diagenesis, low concentrations of rare earth and trace elements in siliceous shale do not change in ocean water-derived fluids. The Rapitan type, when the Earth’s oceans were almost completely covered by ice and cut off from the atmosphere, the ferruginous quartzite was deposited in the water at a time when the oceans were re-oxygenated. Prominent deposits of superior-type ferruginous quartzite occur in Paleoproterozoic sedimentary basins or in shallow-water sedimentary rocks of the continental shelf (Dartsagt, Ereen). Iron skarn deposits are divided into calcic, magnesian, and scapolite (albite) by their general chemical composition. Calcic iron skarn is developed at contact of carbonate bearing rocks and basic intrusion, and ore consists of magnetite, chalcopyrite, cobaltite, and pyrrhotite. Host rocks of magnesian iron skarn are typically dolomite, or limestone, quartzite, and schist associated with dolomitic. Ore minerals are recognized as magnetite, chalcopyrite, pyrite, sphalerite, arsenopyrite, and pyrrhotite in these type deposits (Bargilt). Host rocks are andesite, tuff, limestone, argillite at the scapolite (albite) iron skarn, then magnetite, hematite, pyrite, marcasite, chalcopyrite, sphalerite, pyrrhotite, and arsenopyrite are ore minerals.