Marine mitieral occurrences include a large number of metallic, nonmetallic, and energy minerals which occur throughout the ocean regimes from shallow (sea-level) beach deposits to deep-ocean (> 5,000 meters) manganese nodules. Although many of the marine minerals have been, and continue to be, commercially exploited, many others require changes in economics or technology before they can be commercially developed. In particular, manganese nodules, cobalt-rich manganese crusts, and polymetallie sulfide occurrences, which are the focus of the present paper, must all be considered as possible future sources of metals because no commercial mining operation now exists for these occurrences.
In order to evaluate the potential of both the marine metallic occurrences that are exploited at present and those that may be developed in the future, we will use the McKelvey (1972) classification of resources and the definition of a resource as, ''A concentration of naturally occurring solid, liquid or gaseous material, in or on the Earth's crust in such form that economic extraction of a commodity is currently or potentially feasible" (V.S. Dept. of Interior, 1973, 1974). The term resource will be used in this article to denote both the currently and potentially economic concentrations of marine min rals. Utilizing this definition to include both present and future developments, we will see that the role of marine mineral resources in international minerals supply may increase significantly in the next two decades and beyond.
The objective of this paper is to present a concise summary of a limited subset of marine metallic resources, emphasis being placed on the economic geology of known occurrences of metallic minerals, primarily those that have formed in the newly defined jurisdictional zones of nations within the Asia-Pacific region. The discussion is specifically limited to these minerals and avoids a discussion of hydrocarbons which are covered elsewhere in this issue (Valencia and Marsh).
This paper is organized into five sections, including ihis introduction. In the next section we present a brief historical sketch ofthe development of marine mineral (including petroleum)resources under the assumption that these facts are not part of the general knowledge. Next, in what is perhaps the most important section, we survey three relatively deep ocean metallic mineral occurrences, manganese nodules, cobalt-rich manganese crusts, and polymetallie massive sulfides. In the fourth section we look at the potential impact of hypothetical future marine mineral mining opprations on projected markets. In the concluding fifth section the results are summarized and evaluated.
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