Deep-sea metallic deposits

Intensive research activities of the past 20 years have revealed certain new ocean mineral resources, such as the ferromanganese deep-sea nodules and crusts as well as the massive sulphide deposits formed along parts of mid-ocean rift systems. Deep-sea metallic deposits might be mined in the 1990's, when various economic and technical factor become more favourable. First, a balanced solution for the legal problems should be found through the UN Conference on the Law of the Sea to safeguard the interests of both industrialized and developing countries. A more liberal regime for marine scientific research and the incorporation in tenets of ocean governance of more economic considerations related to the exploration and exploitation of the deep-sea deposits would enhance benefits for all countries and for the international community as a whole.

Hydrothermally formed massive sulphide occurrences have been described in the axial regions of the East Pacific Rise and the Galapagos Rift system. Some of these deposits have contents of up to 21% Cu, 50% Zn, and 45% Fe and may sometimes be located within the 200-mile limits. The principal marine minerals of great economic potential are ferromanganese nodules and crusts. Although it has been estimated that there are some 10¹² tons of nodules in the Pacific Ocean alone, only a small percentage of these deposits contains 2% of Ni + Cu + Co and occurs in abundances greater than 10 kg m⁻² over an area sufficient for the production of a “20-years mine site”. The highest quality nodule fields with respect to metal grade (Ni + Cu) and abundance exist in the NE Pacific nodule belt. The chemical composition and distribution of nodules and crusts are controlled by certain geochemical and environmental factors. Types of nodules and crusts reflect different processes for formation and different sources of metals. Ferromanganese encrustations from seamount regions are particularly rich in Co and exist in shallower water depth. Considering the regional abundance, there is no indication that economic-grade nodule fields occur within national EEZs; however, Co-rich ferromanganese seamount deposits are sometimes located close to 200-mile limits.