OCCURRENCE AND GENESIS OF THE FERROMANGANESENODULES AND CRUSTS IN THE ARCTIC OCEAN

The distribution, chemistry, mineralogy and chronology of ferromanganese nodules and crusts in the Arctic Ocean are studied in this paper through a thorough review of published papers. There are two types of ferromanganese deposits in the Arctic. The shallow water type of ferromanganese deposits occur in the Kara Sea and Chukchi Sea, while the deep water type located in the Chukchi Plateau, Canada Basin, Mendeleev Ridge and Alpha Ridge. The deep water type is mainly formed by hydrogenetic precipitation. The contents of critical metals in the deep water ferromanganese deposits are much higher than those in the shallow water type except for Mn. The contents of critical metals are comparable with the ferromanganese deposits with great economic potential found in the other parts of world ocean. Therefore, the deep water ferromanganese deposits in the Arctic Ocean are regarded in this paper as a kind of potential resource for these metals. According to the dating data, the deep water ferromanganese deposits in the Arctic Ocean began to form in Miocene about 15 Ma, when the Fram Strait opened up and the deep water exchange initiated between the Arctic Ocean and North Atlantic Ocean. Shallow water ferromanganese deposits are formed by diagenetic process, the excessive supply of terrigenous nonmetallic materials accelerated its growth rate. Therefore, it has a lower potential to be a mineral resource.