Magnesian-Magnetite Ore Formation

Abstract Iron mineralization is widely developed within the Angaro-Vilujsky ore belt [2]. In the Noril’sk region, it is found along the western border of the Tungussky syncline and also within the Noril’sk-Kharayelakh depression. The Angaro-Noril’sk metallogenic zone contains some iron mineralization (as deined by N. V. Pavlov [103]). This metallogenic zone is controlled by the Imangdinsky-Letninsky fault zone and is best developed in the basin of the Letnyaya, Severnaya and Kurejka rivers. Iron-bearing deposits of the Angaro-Vilujsky belt are localized within an area of volcano-tectonic structures which is 60 x 130 kilometers in extent. These deposits occur as shallow domes and basins within Paleozoic to early Mesozoic rocks; at the margins they are rimmed by multiple fractures, crush zones and associated hydrothermal alteration, by arcuate trap dykes and diatremes. The circularity of the structures is reflected in the magnetic fields, which are characterized by a simple pattern in the central part and by a complicated pattern at the periphery. They are connected with crustal magmatic chambers, which are believed to be 8 to 15 kilometers deep. The roots of the deposits are connected with the evolving intermediate chambers, which are probably very extensive vertically and interconnect with a mantle source. These considerations are based on geological data and on K-Ar dating of the volcanic pipes (220+/-25 million years) and the magnesian-magnetite hydrothermal mineralization (160 to 100 million years). The deposits formed as a result of the interaction between basaltic magma in the intermediate chamber and mantle fluid; this led to