ABSTRACT

Cobalt-rich manganese crusts are known to occur in potentially economic concentration within the EEZ areas of several Trust and Affiliated Territories and are inferred to occur in many others. A resource assessment of the potential of cobalt-rich manganese crusts was completed and based on the analysis, the following is a ranking of the U. S. Trust and Affiliated Territories, in decreasing order in terms of 'potential for economically viable concentration of co bal t crusts:

  1. Federated States of Micronesia,

  2. Marshall Islands,

  3. Commonwealth of Marianas,

  4. Kingman-Palmyra,

  5. Johnston Island,

  6. Wake,

  7. Jarvis,

  8. Belau-Pal au,

  9. Guam,

  10. Howland-Baker, and

  11. Samoa.

INTRODUCTION

The discovery of ferromanganese occurrences on the abyssal depths dates to 1874 when the HMS Challenger recovered the first manganese nodule from the seafloor. The possibility of recovering nickel, copper, cobalt, and manganese from manganese nodules (hereafter referred to as nodules) was the object of major exploration efforts by various governments and companies during the 1960s and 1970s and of major concern during the decade-long negotiations for the Law of the Sea Treaty.

Recently, the interest of the scientific community has shifted from nodules to cobalt-rich manganese crusts (hereafter referred to as crusts) associated with seamounts and guyots. There are a number of factors that appear to be contributing to this shift, including a recent recognition that crusts (1) may be richer in metal content and more extensively distributed than previously recognized; (2) may be technologically easier to recover; (3) may be located in a more stable investment environment; and (4) may provide alternative sources of strategic metals. As a result the thesis of this study is that there are probably extensive crust deposits within the EEZ's of the U. S. Trust and Affiliated Territories and that these will prove to be closer to commercial viability than deep-sea nodules.

The scope of this paper is limited by the availability of data sources concerning co balt rich manganese crusts. This limitation results because crusts (a) are a new and only recently studied resource; (b) extensive studies have not been conducted in any area; and (c) many areas of the U. S. Trust and Affiliated Territories have not been investigated. It is possible that large numbers of seamounts, and therefore areas of crust resources, are not included in the present analysis because of insufficient research in the areas.

PHYSICAL GEOLOGICAL CONTROLS

Cobalt-bearing manganese crusts range from coatings to thick pavements covering submarine volcanic and phosphorite rocks (Craig et ale 1982).Recent studies by Hal bach and Manheim Islands); Craig et ale (1982), and Frank et ale (1976) (Hawaiian Archipelago) demonstrated the presence of cobalt-rich manganese crusts and nodules associated primarily with seamounts and guyots, over areas sufficiently large to support possible ocean mining ventures.

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