Minerals Report - International Seabed Authority

mid-ocean ridge, to look at hydrothermal activity there, and to identify where
it occurs.
Dr German informed participants that his presentation on “ Current
national and international programmes of exploration for seafloor massive
sulphides and state-of the-art techniques and operations in exploration “
would contain some information on the working group’s functions starting
with images of black smokers, information on the geological controls that
determine where hydrothermal vents occur around the world’s ridge crest,
information on whether or not hydrothermal vents are evenly distributed, and
how one actually goes to a new part of the ocean that nobody has looked at
before, and conducts a search for hydrothermal activity. Following this, Dr
German said that his presentation would describe how one assesses the
resource potential of hydrothermal sites, and the type of baseline information
that may be gathered during a preliminary survey of an area.
With regard to hydrothermal vents in the deep sea, particularly in the
Area, Dr German said that they are to be found typically at depths of a few
thousand metres. He described the phenomenon of a hydrothermal vent as
comprising seawater circulating down through fractured seafloor towards the
oceanic crust where it reacts with fresh volcanic lava, expanding and suffering
a loss in viscosity. At temperatures of 350 to 400 degrees centigrade, the clear
hydrothermal fluid formed in the reaction rises to the seafloor and erupts as
sulphides chimneys. Dr German described the fluid as very hot and very
acidic and saturated with metals. When the fluid comes to the seafloor and
begins to mix with ordinary seawater, it is first cooled, quenching the fluid
and thus precipitating sulphide minerals, and with oxygen contained in
ordinary seawater, produces reactions that result in smoke that is manifested
as black and white “smokers”.
From an academic point of view, Dr German said that one of the
reasons for looking at hydrothermal activity around the world’s oceans is to
obtain an understanding of the life forms around them. He said that in the
Pacific at these sites, the life forms are actually living in simmering water. He
showed pictures of tubeworms that are characteristic of the Pacific Ocean
which grow up to eight feet long, and which are actually drawing on the
dissolved hydrogen sulphide coming out of hydrothermal systems and
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