Minerals Report - International Seabed Authority
Minerals Report - International Seabed Authority Minerals Report - International Seabed Authority
Figure 4. A diagrammatic east-west cross-section of the Pacific Ocean between South America and eastern Asia shows the relation of potential mineral and energy resources to submerged divergent (East Pacific Rise) and convergent (Pacific margins) plates, as discussed in the text (8). Metal deposits including massive sulphides may occur in ocean crust represented by the black layer at the top of the lithosphere. Examples of these settings at the front and back sides of volcanic island chains are, respectively: 1) the Sunrise deposit in the collapsed crater of an active seafloor volcano in the fore arc side of the Isu-Ogasawara Arc south of Japan (9), and; 2) the PACMANUS hydrothermal field in the Manus back arc basin on the north side of Papua New Guinea (10), which is under development for mining. A characteristic of these mineralised seafloor sites in the western Pacific is that they lie not only within the 200 nautical mile zone of adjacent coastal states but, in certain cases, lie in overlapping 200 nautical mile zones. The massive sulphide and manganese deposits precipitated from relatively high-and low-temperature hot springs, respectively, occur primarily in the volcanic rocks of the ocean crust that is typically the upper 5 kilometres of the lithosphere. Metallic mineral resources of the Earth's mantle, which underlies the ocean crust, are poorly known because of limited exposures of these deeper sub-seafloor rocks. The types of deposits anticipated in the upper mantle comprise chromium in the form of podiform chromite deposits and nickel- and platinum-rich mineral phases. INTERNATIONAL SEABED AUTHORITY 82
4. Marine Minerals Related to Continental and Deep Ocean Sources 4.1 Manganese Nodules Ever since John Mero published his book, "The Mineral Resources of the Sea”, in 1965 ( 11/ ) when he has a graduate student studying marine geology, manganese nodules have been the quintessential deep ocean mineral. Mero's estimates of the in situ value of the metals contained in manganese nodules without accounting for the substantial costs of recovery and refining created a "gold rush" mentality about marine minerals at that time which contributed to drive the development of the UN Convention on the Law of the Sea (UNCLOS). The golf- to-tennis-ball sized nodules lie on and in sediment that covers the seafloor in the vast expanses of the abyssal plains of the world's ocean basins (Figure 1). The portion of the nodules that protrudes above the surface of the seafloor sediment is precipitated from metals dissolved in seawater (authigenic or hydrogenous origin; Table 1), while the underside of the nodules accumulates from metals dissolved in the pore water of the sediment (diagenetic process; Table 1) over millions of years. The metals come from two sources. Manganese and other metals are dissolved by weathering of rocks on continents and transported into the ocean by rivers. At the same time hot springs at sites along submerged volcanic mountain ranges (divergent plate boundaries) discharge dissolved metals into the ocean. The result is a mixture of copper, nickel, manganese, cobalt and iron in the nodules that varies in different regions of the ocean related to proximity to sources of the metals and other factors. 4.2 Cobalt-rich Ferromanganese Crusts Sources of metals that form cobalt-rich ferromanganese crusts of the deep ocean are derived from both continental and deep ocean sources and are precipitated from seawater like manganese nodules ( 12/ ). The metals in addition to iron and manganese include cobalt, nickel, platinum, and titanium depending on proximity to different sources. These metals precipitate at slow rates over millions of years as crusts up to about 25 cm thick on hard-rock substrates of seamounts and submerged volcanic mountain ranges between ocean depths of 400 and 4000 meters. These crusts are most widespread in the Pacific Ocean because of the large number of seamounts present. Recovery INTERNATIONAL SEABED AUTHORITY 83
- Page 40 and 41: esearch cruises dedicated to ferrom
- Page 42 and 43: global mid-ocean ridge system. He p
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- Page 76 and 77: Chapter 7 Technical requirements fo
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- Page 110 and 111: like St. Stephen’s in the Kremlin
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Figure 4. A diagrammatic east-west cross-section of the Pacific Ocean between South America and<br />
eastern Asia shows the relation of potential mineral and energy resources to submerged divergent (East<br />
Pacific Rise) and convergent (Pacific margins) plates, as discussed in the text (8). Metal deposits<br />
including massive sulphides may occur in ocean crust represented by the black layer at the top of the<br />
lithosphere.<br />
Examples of these settings at the front and back sides of volcanic<br />
island chains are, respectively: 1) the Sunrise deposit in the collapsed crater of<br />
an active seafloor volcano in the fore arc side of the Isu-Ogasawara Arc south<br />
of Japan (9), and; 2) the PACMANUS hydrothermal field in the Manus back<br />
arc basin on the north side of Papua New Guinea (10), which is under<br />
development for mining. A characteristic of these mineralised seafloor sites in<br />
the western Pacific is that they lie not only within the 200 nautical mile zone<br />
of adjacent coastal states but, in certain cases, lie in overlapping 200 nautical<br />
mile zones.<br />
The massive sulphide and manganese deposits precipitated from<br />
relatively high-and low-temperature hot springs, respectively, occur primarily<br />
in the volcanic rocks of the ocean crust that is typically the upper 5 kilometres<br />
of the lithosphere. Metallic mineral resources of the Earth's mantle, which<br />
underlies the ocean crust, are poorly known because of limited exposures of<br />
these deeper sub-seafloor rocks. The types of deposits anticipated in the<br />
upper mantle comprise chromium in the form of podiform chromite deposits<br />
and nickel- and platinum-rich mineral phases.<br />
INTERNATIONAL SEABED AUTHORITY 82
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