Minerals Report - International Seabed Authority

Professor Herzig said that the deposits that have been discovered in
the Atlantic Ocean at the Mid-Atlantic Ridge, was in large part due to the
work of Russian and the British scientists during their so-called Bridge
programme. He stated that in the Indian Ocean two sites have been
discovered: the Sonne Field and the Mount Jordan Field. He made the point
that the number of deposits at the different mid-ocean ridges is a reflection of
the prospecting activity in those areas. He further made the point that
increased prospecting activity in the Indian Ocean for example would result
in more discoveries.
Professor Herzig noted that two unusual discoveries have been made
in the Southwest Pacific. One of these he said is close to 21˚N in the
Guayamas Basin in the Gulf of California. This site, Professor Herzig said, is
hydrothermally active and the rift to found there is filled with several
hundred metres of terrigeneous sediments. Sulphide precipitation in this case
he also said, takes place within the sediment and creates a very effective
means of concentrating metals without the metals getting lost through the
black smokers. He concluded that the presence of the sediments has created a
very efficient way of forming a big massive sulphides deposit.
Professor Herzig turned his attention to the metalliferous brines to be
found in the Atlantis II Deep in the Red Sea. Noting that this deposit was the
earliest discovery of a seafloor massive sulphides deposit (1965), he informed
participants that it differed from other seafloor massive sulphides because the
hot hydrothermal fluid from the magma chamber mixes with highly saline
seawater in the Deep. He further noted that the evaporates that occur in the
Red Sea are typical for a young ocean that used to be an intercontinental rift
with episodic transgression of seawater. This turn of events, he stated,
produced thick salt layers that were moved to the flanks of the Deep where
seawater circulates through them. The seawater, as a result, becomes highly
saline, producing a metal-rich brine as compared with a metal-rich fluid that
jets out of black smoker chimneys. These metal rich brines, he further stated
are being deposited in various deeps in the Red Sea.
Professor Herzig reiterated the statement made by Professor Rona that
the German Preussag Company under contract with the Saudi-Sudanese Red
Sea Commission investigated the Red Sea metalliferous sediments. He noted
INTERNATIONAL SEABED AUTHORITY 150