center while zinc, iron sulfide and colloidal iron sulfide are more plentiful
towards the exterior of the mound.
(5) When fracturing of the sea floor takes place during tectonic events, the formation of normal faulted scarps will also occur. The fault scarps can expose
the veins of mineralization (stockwork) and a talus of slumped material will
collect at the foot of the faulted scarps (Fig. 6.5e)
Thus, a metalliferous deposit is an oval-shaped structure containing more than
3,000 tons of material that originates from the evolution of distinct hydrothermal
events (Fig. 6.5a–e). During its construction, it will assume various shapes such as
columnar edifices, massive sulfide mounds, breccia, slumped talus material, etc.
(See paragraphs on types of hydrothermal deposits).
Exploitable Mineral Resources of the Sea Floor
The major metallic elements found and exploited in metalliferous deposits on land
are iron (Fe), cobalt (Co), copper (Cu), zinc (Zn), palladium (Pd), silver (Ag),
antimony (Sb), gold (Au), platinum (Pt), tin (Sn), aluminum (Al) and lead (Pb).
Many of these occur in seafloor deposits but are not yet exploited. Deep-sea
deposits other than sulfides are manganese nodules and manganese crusts. The
best-known exploitable undersea deposits of nodules are located between the
Clarion and Clipperton fracture zones in the Pacific Ocean. Only about 10 % of the
total area covered by nodule accumulation on the sea floor, with an average 2.4 %
content of copper ? zinc ? cobalt, is comparable to that of the entire terrestrial
sulfide ore deposits (Exon et al. 1992). The manganese crusts are of particular
interest because of their high content in the platinum group elements. They are also
easier to mine because they are found in shallower water depths than the manganese nodules ([4000 m depth).
Hydrothermal deposits are important for industry and their exploitation goes
back to the dawn of civilization (Scott 1987). Sulfide deposits on the Island of
Cyprus have been exploited for copper for more than 2500 years and were mined
during the Roman Empire. In fact, the Island of Cyprus was uplifted from the sea
floor during the Tertiary period more than 120 million years ago and has the
characteristics of a modern oceanic ridge fragment. The metalliferous deposits
found on Cyprus were formed over a period of about 12,000 years and contain 4–7
million tons of ore. Cyprus is a good area for geologists to explore exposed, landbased hydrothermal deposits so scientists who want to better understand the sea
floor environment often visit the island.
The exploitation of ocean floor hydrothermal deposits is becoming a reality.
However, the exploration of the sea floor should continue in order to provide more
information on the deposits. This will help to better understand the chemical and
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6 Hydrothermal Activity and Metalliferous Deposits
towards the exterior of the mound.
(5) When fracturing of the sea floor takes place during tectonic events, the formation of normal faulted scarps will also occur. The fault scarps can expose
the veins of mineralization (stockwork) and a talus of slumped material will
collect at the foot of the faulted scarps (Fig. 6.5e)
Thus, a metalliferous deposit is an oval-shaped structure containing more than
3,000 tons of material that originates from the evolution of distinct hydrothermal
events (Fig. 6.5a–e). During its construction, it will assume various shapes such as
columnar edifices, massive sulfide mounds, breccia, slumped talus material, etc.
(See paragraphs on types of hydrothermal deposits).
Exploitable Mineral Resources of the Sea Floor
The major metallic elements found and exploited in metalliferous deposits on land
are iron (Fe), cobalt (Co), copper (Cu), zinc (Zn), palladium (Pd), silver (Ag),
antimony (Sb), gold (Au), platinum (Pt), tin (Sn), aluminum (Al) and lead (Pb).
Many of these occur in seafloor deposits but are not yet exploited. Deep-sea
deposits other than sulfides are manganese nodules and manganese crusts. The
best-known exploitable undersea deposits of nodules are located between the
Clarion and Clipperton fracture zones in the Pacific Ocean. Only about 10 % of the
total area covered by nodule accumulation on the sea floor, with an average 2.4 %
content of copper ? zinc ? cobalt, is comparable to that of the entire terrestrial
sulfide ore deposits (Exon et al. 1992). The manganese crusts are of particular
interest because of their high content in the platinum group elements. They are also
easier to mine because they are found in shallower water depths than the manganese nodules ([4000 m depth).
Hydrothermal deposits are important for industry and their exploitation goes
back to the dawn of civilization (Scott 1987). Sulfide deposits on the Island of
Cyprus have been exploited for copper for more than 2500 years and were mined
during the Roman Empire. In fact, the Island of Cyprus was uplifted from the sea
floor during the Tertiary period more than 120 million years ago and has the
characteristics of a modern oceanic ridge fragment. The metalliferous deposits
found on Cyprus were formed over a period of about 12,000 years and contain 4–7
million tons of ore. Cyprus is a good area for geologists to explore exposed, landbased hydrothermal deposits so scientists who want to better understand the sea
floor environment often visit the island.
The exploitation of ocean floor hydrothermal deposits is becoming a reality.
However, the exploration of the sea floor should continue in order to provide more
information on the deposits. This will help to better understand the chemical and
162
6 Hydrothermal Activity and Metalliferous Deposits