Seafloor Massive Sulfides / Deep Sea Mining

Seafloor Massive Sulfide (SMS), Deep Sea Mining:

Much attention is being directed now at the likely emergence of a new industry in the world’s oceans: Deep Sea Mining. Unlike earlier attempts to recover manganese nodules from the deep ocean, commercial interests currently are focusing on seafloor massive sulfides (SMS) located in basins and volcanoes on convergent plate boundaries at the shallower water depths of 2km. Many questions exist about the environmental sustainability of underwater mining; public policies are under development to assess impacts, protect ecosystems, and distribute resource rents. These policies are yet to be determined, and oceanography may help shed light on the relevant questions, thereby increasing the likelihood that seafloor mineral occurrences do become economic reserves.

SMS are base metal (Fe, Cu, Zn, Pb), sulfur-rich mineral deposits that precipitate from hydrothermal fluid as it interacts with the cooler ambient seawater at or beneath the seafloor at hydrothermal vent sites. SMS deposits are found in as many as a dozen different tectonic settings but most occur along the mid-ocean ridge system. Up to 40% of the known deposits occur at shallower depths in basins and along submarine volcanic ridges within 200 nautical miles of the coast, within the jurisdiction of national exclusive economic zones (EEZs).

There may be as many as 1000 active seafloor hydrothermal sites worldwide, but systematic exploration for active sites along the global ridge-crest remains limited and a database maintained by the International Seabed Authority (ISA) currently lists only 327 active and inactive sites that have been documented to date. At present, only about 100 of these hydrothermal sites are known to host significant SMS mineralization. In order to become commercial prospects, SMS deposits must be able to compete with land-based supplies on the basis of advantages in size, grade, and, accessibility.

A principal function of the ISA is to regulate deep seabed mining and to give special emphasis to ensuring that the marine environment is protected from any harmful effects which may arise during mining activities, including exploration. The Authority also has the responsibility to promote and encourage marine scientific research in the international seabed area and to disseminate the results of such research. RDSEA has recently been engaged by the SMS mining community to help with the initial environmental impact assessments (EIA) required for the permitting process to help secure mining tenement regions along the seafloor in the Pacific. Combing MetOcean in-situ measurement parameters, water column and seafloor geochemistry, a clear picture of these mining areas offshore can be established. Regional MetOcean and wave parameter models are also available.

See this recent publication for more information: Deep-sea Miners Engage Physical Oceanography (PDF)

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