Hein, et al., reported in 2009 that regulations are being developed through the International Seabed Authority (ISBA) for the exploration and mining of cobalt-rich ferromanganese crusts. The authors propose geologic and geomorphologic criteria that can be used to determine the size and number of exploration and mine-site blocks that will be the focus of much discussion within the ISBA Council deliberations. The surface areas of 155 volcanic edifices in the central equatorial Pacific were measured and used to develop a mine-site model. The mine-site model considers areas above 2,500m water depth as permissive, and narrows the general area available for exploration and mining to 20% of that permissive area. It is calculated that about eighteen 100 km2 exploration blocks, each composed of five 20 km2 contiguous sub-blocks, would be adequate to identify a 260 km2 20-year-mine site; the mine site would be composed of thirteen of the 20 km2 sub-blocks. In this hypothetical example, the 260 km2 mine site would be spread over four volcanic edifices and comprise 3.7% of the permissive area of the four edifices and 0.01% of the total area of those four edifices. The eighteen 100 km2 exploration blocks would be selected from a limited geographic area. That confinement area is defined as having a long dimension of not more than 1,000 km and an area of not more than 300,000 km2.
The authors emphasize that the paper discusses a hypothetical illustration and is not a recommendation nor indication of potential mine sites. The area considered includes the largest guyot measured here and several smaller nearby guyots that we use for our model exploration and mine site, which span the northwest border of the Republic of the Marshall Islands EEZ. The 300,000 km2 confinement area includes guyots with a total surface area above 2,500 meter water depth of 12,723 km2, which includes many seamounts not used in the authors' illustration as potential exploration targets; total area excludes atolls.
Based on previous prospecting, exploration blocks would be chosen. Seamount A has a total surface area of 3,076 km2 above 2,500 meter water depth, of which 23% is chosen here to be included in the exploration license. If 59% or more of the permissive surface area of this single guyot was found to be appropriate for exploration, then this single edifice could accommodate the license for the confinement area. Figures show the eighteen 100 km2 blocks illustrated here for the model mine site to be licensed for exploration, each composed of five 20 km2 sub-blocks. The area licensed for exploration covers 22.8% of the total area above 2,500 meters for those six edifices and the mine site covers 3%, or 3.7% of the area above 2,500 meter on the four edifices with identified mine-site sub-blocks. The final mine site would cover 0.01% of the total area of the four impacted edifices. Some of the exploration territory would be relinquished during two or more stages during the lifespan of the license, finally ending up with thirteen 20 km2 sub-blocks that would define the final 260 km2 mine site. In this example, the eighteen 100 km2 exploration blocks are not always contiguous and the final choice of thirteen 20 km2 sub-blocks for mining operations are also not always contiguous, but both types of blocks commonly occur in clusters. This same lease-block analysis can be made for a 15-year mine-site scenario in which case the areas needed for exploration and a mine-site would be significantly less.
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