Minerals Report - International Seabed Authority

With regard to the gold values reported from the Logachev 2 field,
another participant requested that one would have to find out about the
number of samples analysed and the method that has been used to analyse
the gold, because 424ppm, with a maximum of 875ppm is unbelievably high.
He stated that based on his experience in analysing seafloor massive
sulphides he found these numbers to be unbelievable.
Another participant, however, pointed out that it was very interesting
that the deposits at the Logachev field at 14 o 45’ N, which were discovered on
the Mid-Atlantic Ridge are partially hosted in the ultramafic rocks of the
upper mantle. He pointed out that the ultramafic rocks provide a suite of
metals for leaching by the hydrothermal process that are different from the
overlying mafic rocks of the ocean crust. In this instance, he further pointed
out; one would expect to find chromium rich and nickel-rich phases in the
form of chromate, like the podiform chromite deposit from the Semi ophiolite
in Oman. As a result he stated that one would expect a different suite of
mineral deposits related to these fields. He also stated that the Russian
discoveries open up another dimension to deep ocean mineral deposits, those
related to the upper mantle, and that the international scientific community is
just beginning to learn about this. He concluded that mankind’s
understanding of marine mineral deposits continues to expand as we advance
in terms of our scientific knowledge of the ocean and the earth.
One of the workshop’s participants sought clarification from Dr. Rona
on the various references to the TAG mound in Dr. Cherkashev paper. Dr
Rona responded that the correct name should be the TAG field, containing the
TAG active mound, the MIR inactive mound and the Alvin inactive mound.
He pointed out that there are three mounds in the TAG field.
Dr. Rona further pointed out that the TAG hydrothermal field is
actually an area about 5km by 5km, encompassing part of the floor and east
wall of the rift valley that includes both active and inactive massive sulphides
mounds. The mound that was drilled is the active high-temperature mound
with the active black smokers at the top; the one that the analogy with the
Houston Astrodome is made. The MIR mound which was just described in
this paper by Cherkashev and others, is about 2 km to the east of the TAG
active mound, on the lower east wall but within the TAG hydrothermal field.
INTERNATIONAL SEABED AUTHORITY 186