Minerals Report - International Seabed Authority

4.4.4 Resource potential of marine polymetalic sulphides deposits
Very little is known about the total metal content of sub-sea PMS
deposits and their sub-surface extent. However, it is unlikely that sub-sea
PMS deposits, such as those located in international waters on the midocean
ridges (e.g. the Mid-Atlantic Ridge, East, Northeast and Southeast
Pacific Rises, and the Indian Ocean ridges), will become mining targets in
the forseeable future (Agterberg, F.P. and Franklin, 1987). This is largely
because of their depth (greater than 2500 m) and remote locations from
shore. However, marine mining may become economically viable under
some conditions where there are high gold and base-metal grades, sites are
located close to land, and in water depths less than 2000 m. Under those
circumstances, massive sulphide mining may become economically viable
(Broadus, 1985).
With reference to Figure 10, showing the locations of known
hydrothermal activity and PMS deposits and their geologic setting, it is
possible to identify those areas where conditions for recovery may become
viable. These are: the south-west Pacific, the Scotia Sea, the Guyamus
Basin (Gulf of California), northern East Pacific Rise, the Mid-Atlantic
Ridge south of the Azores islands, and possibly parts of the Juan de Fuca
Ridge of western North America.
Only the PMS deposit known as lucky Strike on the Mid-Atlantic
Ridge, located to the south of the Azores islands lies within potential areas
of extended legal continental shelf (ELCS). Even for those PMS deposits
that are already known, and lie within 200 nautical miles of coastal states,
the logistical difficulty for mineral recovery make them all currently paramarginal
resources. The only exception to this is the PACMANUS deposit
in the Eastern Manus Basin (Bismarck Sea, north of Papua New Guinea),
for which the Papua New Guinea authorities granted in 1999 two
exploration and development licences to Nautilus Mineral Corporation
PLC.
4.5 Marine manganese nodules and crusts
4.5.1 What manganese nodules and crusts comprise
Manganese nodules are concentrations of iron and manganese
oxides, ranging from millimetres to tens of centimetres in diameter. They
can contain economically valuable concentrations of nickel, copper and
INTERNATIONAL SEABED AUTHORITY 694