Minerals Report - International Seabed Authority

Professor Herzig said that the spectacular black smokers are the result
of this process and that they represented the chimneys of an “ore factory”
operating at the seafloor. He emphasized that the important part of the “ore
factory” is below the chimneys. Utilizing a slide containing a picture of the
TAG mound at the Mid-Atlantic Ridge, Professor Herzig illustrated his point,
pointing out the black smoker complex, which has about several dozen high
temperature black smokers in a temperature of 360˚ C, on top of a mound
feature about the size of the Houston Astrodome, or 200 m in diameter and 50
m high.
With another slide, Professor Herzig showed a picture of a massive
sulphides rock that was taken using a TV guided grab from the Galapagos
spreading centre. He described this sample as consisting of sphalerite,
chalcopyrite, amorphous silica and some other minerals with a geologic age of
several hundred years. Using another slide containing a picture of a similar
rock, Professor Herzig explained that although this massive sulphides rock is
crystallised, its mineralogy is very similar to the picture previously shown.
He informed participants that the difference between the two samples
was that while the former picture is of a seafloor massive sulphides rock, the
latter is of a sample of ore from a land-based massive sulphides deposit, that
is part of the Troodos ophiolites on the island of Cyprus and that are about 80
million years old.
Professor Herzig disclosed that a very close relationship existed
between modern hydrothermal system massive sulphides at the seafloor and
ancient sulphide deposits on the continents. He illustrated this point with a
slide of one of the big Canadian deposits, the Kidd Creek deposit. He noted
that the Kidd Creek deposit that is 2.7 billion years old has a total volume of
135 million tonnes of massive sulphides. He referred to indications from
other areas that show that hydrothermal processes have been taking place on
the bottom of ancient oceans for more than 3 billion years and concluded that
this process that is being observed today at the seafloor is more than 3 billion
years old.
Professor Herzig informed participants of the distribution of
significant massive sulphides mines and deposits in the world. With regard
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