Minerals Report - International Seabed Authority

esearch cruises dedicated to ferromanganese crusts prospecting that he was
aware were undertaken during 1981 and 1999, Dr. Hein estimated that
approximately US $70 million had been invested in the early stages of
ferromanganese crusts deposits development.
Dr. Hein informed workshop participants that at the present time,
with regard to the distribution of crusts deposits, they have been found
throughout the world’s ocean basins: from the farthest northern parts of the
Pacific Ocean, in the Atlantic Ocean, and down to the Antarctic ridge. They
occur in water depths of about 400 – 4,000 meters, but more commonly at 1000
– 3000 meters. The thickest crusts occur on the summits of seamounts, in
summit terraces, and in summit saddles. The most cobalt-rich crusts are found
between 800 – 2,500 meters water depth, primarily because of the oxygen
minimum zone (OMZ). The area of the ocean basins highest in cobalt content
is the central equatorial Pacific Ocean basin. The Indian and Atlantic Oceans
are not dominated by seamounts like this part of the Pacific Ocean. In
addition, since these two ocean basins are much smaller than the Pacific, and
are affected by huge rivers such as the Amazon, and huge deserts such as the
Sahara, a lot of wind blown detritus finds its way into these ocean basins,
diluting the grade of crusts. In general therefore, Dr. Hein stated that the
dominant areas of crusts with high cobalt content are neither the Atlantic
Ocean basin, nor the Indian Ocean basin, nor the continental margins of the
Pacific Ocean, but far away in the central Pacific Ocean basin at seamounts to
be found there.
With regard to biological communities that inhabit seamounts, Dr.
Hein noted that very few studies have addressed seamount biological
communities around crusts deposits even in the central equatorial Pacific
Ocean basin. He stated that the studies that had been done concentrated on
seamounts with a sediment cap and on biological communities living on
(epifauna) and in (in fauna) that sediment. Fewer studies have addressed
communities dwelling on the rock outcrops. Initial results indicate that
seamount biological communities are relatively low density and low diversity
species, because of the low oxygen content in the oxygen minimum layer. He
stressed the need to understand the nature of the biological communities
around these deposits so that the appropriate information can be incorporated
in environmental impact information.
INTERNATIONAL SEABED AUTHORITY 32