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By Jan M. Peter

Many massive sulfide deposits and districts around the World contain rocks that are variously referred to as ?exhalites?, banded iron formation (IF), ?Algoma-type? IF, ferruginous chert, jasper, jasperoid, cherty tuff, tuffite, tuffaceous exhalite, chloritic IF or sulfide IF. With few exceptions, such rocks are thought to be (in part) fossil hydrothermal sediments deposited from hydrothermal fluids vented into a submarine rift environment. Such hydrothermal sediments are associated with a wide variety of ancient base-metal sulfide deposits (e.g., Cyprus-, Besshi-, Kuroko-, and Broken-Hill-type deposits), and hydrothermal sediments are commonly associated with some of the largest base metal sulfide deposits in the world. Analogs of ancient hydrothermal sediments can be found around many modern seafloor hydrothermal deposits which themselves precipitate from high-temperature (350°-400°C) hydrothermal fluids. Hydrothermal fluids are quenched on contact with ambient seawater, and most of the metals are immediately precipitated to form the mound and chimney deposits. However, for kinetic and solubility reasons, not all metals and other species are immediately precipitated at the vent site. Fine particles (up to several hundred microns in diameter) of sulfides, sulfates, carbonates, oxides, silica, Fe-oxyhydroxides, clays, and other phases are precipitated from the hydrothermal fluids in the water column above the deposits. These particles or "particulates" are carried upward for several hundred meters in a buoyant hydrothermal plume (which is typically several hundred meters thick) until it reaches a neutral density, and disperses laterally from the vent site. Modelling of plume dynamics has shown that the majority of particulates are deposited by gravitational settling a few hundred meters from the vent site, and Å99% of particulates are deposited within 3 kilometers. However, signals from modern plumes have been detected even hundreds of kilometers from their source. Factors which can affect the morphology of the plume (and the resultant fallout pattern) include: particulate size, shape and density, bottom topography, and the direction and velocity of bottom currents.

Jan 1, 1998

By Stanley R. Riggs

Onslow Bay is a broad, shallow, high-energy shelf system bounded by the Cape Lookout and Frying Pan shoals. It is generally a sediment-starved shelf system dominated by hardbottoms with a scattered and discontinuous veneer of mobile Holocene sediments. Phosphate-rich beds of the Miocene Pungo River Formation crop out in a belt 150 km long and up to 50 km wide across the continental shelf in Onslow Bay, North Carolina. Previous research has demonstrated that a few of these beds contain vast quantities of potentially economic phosphate resources that occur in the surface and shallow subsurface sediments. Onslow Bay contains five phosphate-bearing beds predicted to include up to 20.7 billion tons of in-place phosphate concentrate with total sediment grades ranging up to 22.9% P2O5 and adjusted average concentrate grades of 29.8% P2O5. These phosphates are lithologically and chemically similar to phosphates currently being mined in the nearby Aurora phosphate district in North Carolina. Various lithologies of the Pungo River Formation and associated rock units of Oligocene and Quaternary age crop out on the sea floor to form extensive hardbottom habitats that dominate almost 100% of Onslow Bay. A large proportion of these hardbottoms appear to be sea floor deserts, whereas others are virtual oases with rich associations of benthic organisms. These important differences in benthic community structure appear to be greatly influenced by one or more of the following variables: 1) geologic framework (geologic formation, hardbottom composition, morphology, and spatial orientation relative to dominant currents and waves), 2) texture, movement, and accumulation of surface sediments, and 3) flow rates and chemical composition of discharged submarine groundwater.

Jan 1, 1992

By Alexander Malahoff

The summit of L_ihi submarine volcano changed dramatically after seismic activity beneath L_ihi during the month of August 1996. Bathymetric re-surveys of the L_ihi edifice using SeaBeam, Simrad and deep-towed Reson-Focus multibeam systems showed the presence of new north-south striking fissures, normal faults and a new pit crater located at the site of a former 300-meter high volcanic cone. Comparisons between the pre-1996 SeaBeam data and the new bathymetry show a net loss of about 100 million cubic meters of rock volume on the summit. This loss is localized at a new pit crater -- the 300-meter deep by 1,300-meter wide Pele's Pit. Submersible observations with Pisces V show the northern edge of Pele's Pit to be bounded by a normal fault located north of the site of the former Pele's Vents cone that has disappeared into the new pit crater. A new hydrothermal field, the Ikaika Vents, extending from a water depth of 1,311 meters to 1,287 meters has formed at the northeastern edge of the floor of Pele's Pit. Submersible observations of these new Ikaika Vents during September 1996 showed vigorous venting at the site with extensive white-colored bacterial mats hanging off the rock face above the vents. Follow-up mapping and sampling of the vent sites during August 1997 showed vent temperatures of up to 198°C, dense populations of vent shrimps around the vents and a centimeters-thick veneer of fine-grained polymetallic sulfide mineralization along the rock walls above individual vents. The mineralogy of the sulfides shows a barite, chalcopyrite, sphalerite, and pyrite composition.

Jan 1, 1998

By Grigori Abramov

Borehole Mining (BHM) is a remotely operated underground and underwater method of extracting (mining) mineral resources by high-pressure water jets. It can be carried-out from the land surface, open pit floor, underground mine and floating platform or vessel. The method is currently in use in mining and exploration of such natural resources and industrial materials as: uranium, iron ore, quartz sand, gravel, coal, poly-metallic ores, phosphate, gold, diamonds, rare earths, amber and several more. Yet another application of Borehole mining technology is construction of subsurface collectors, ground walls and storage for compressed or liquefied gases, oil and other products.

By Michael Johnston

Nautilus Minerals is exploring for high-grade gold, silver, copper, and zinc-rich submarine massive sulphide deposits (SMS) within the territorial waters of the sovereign state of Papua New Guinea. Work to date has shown that these systems contain spectacularly high metal grades. To date a total of 88 surface sulphide grab samples have been collected from Nautilus’ Solwara 1 Prospect within EL 1196 in the Manus Basin, returning average grades of 15.5 g/t gold, 191g/t silver, 10.8% copper, and 4.7% Zn. Drilling in January/February 2006 confirmed the presence of this high grade system, with sulphide intersections up to 19m below the sea floor, with a best intersection of 11.6m at 9.1 g/t Au and 13.1% Cu.

By Jon Machin

?ORE? is defined as ?mineral/s that can be mined at a profit?. So, what is ORE at 2,000 m water depth? Is it 5% Copper or 1.8% Nickel/Cobalt? One of the key factors that determine what is ORE, profitable or not, is the cost of mining and extraction. Therefore a determination of ORE requires a commercial and technical appreciation of both sea bed mining equipment and mining options. Perry Slingsby Systems (PSS) have built more remotely operated submarine work vehicles, including 900HP trenching machines, than any other company. With Nautilus Minerals, PSS have been studying a range of deep ocean mining solutions. This paper discusses the commercial and technical issues of various extraction techniques applicable to deep ocean mining from 1,500 m to 5,000 m water depth. Issues such as the rate of extraction, (i.e. tons per hour) is a key economic component and is often constrained by the design and horsepower of the miner. Likewise the design itself of the mining machine and cutting heads can determine the size of material produced which impacts on methods of lifting the ore to surface. Issues such as overburden, sea floor conditions, style of mineralization and physical properties of the ore, obviously affect the selection of appropriate mining machine configuration.

Jan 1, 2004

By Tetsuo Yamazaki

Metal market prices rose drastically in 2006, and most broke historical records as shown in Figs. 1-4. This increase has been basically driven by economic growth in Asian countries, especially China. The growth trend is expected to continue for several years. Then, India will follow the same growth trend. Their metal demands keep the price levels high for 20 years or more. One more additional important factor on the metal market prices is hedge funds come into the market. Japan imports all metals for domestic use from overseas. The amounts imported were 1.27 million tons in copper, 0.32 million tons in lead, 0.59 million tons in zinc, 0.20 million tons in nickel, and 1.18 million tons in manganese, respectively in 2006 (Source: http://www.jogmec.go.jp/j_resourse/index.html#03). Though mainly we import the concentrates and our domestic customer smelters take the part of metallurgical leaching, the payment necessary for purchasing the concentrates is estimated about US$ 10 billions in 2006. The payments in 2005 and in 2003 were about a half and a quarter of the 2006, respectively. Japan must have effective counter measures to reduce the future payments.

Sep 24, 2006

By Alexander Malahoff

A shipboard research system capable of operating in waters of up to 2,000 meters has been designed and implemented by the Hawai'i Undersea Research Laboratory (HURL) of the University of Hawai'i. It uses a remotely-operated ocean bottom survey camera system, an ROV, the Pisces V submersible, and a submersible emergency recovery system, all aboard the 222- foot R/V Ka'imikai-o-Kanaloa. All systems are operated from the stern of Ka'imikai with a mounted Caley telearm and articulated A-frame system. The system was designed for multipurpose use of the ship for launch and recovery of the Pisces V submersible on a lift recovery line (with or without diver assistance), or night-time operations with an electro-optical cable using either the HURL ocean floor sidescan or photo and video system operated at 10 meters above the ocean floor. The 1.14-inch diameter cable is also used to operate an ROV system. The garage/ROV system can also act as a submersible rescue system with a submersible lift capability. The ship is equipped with a SeaBeam and shallow penetration sediment profiling systems. This integrated system approach to deep ocean floor research will make it possible for HURL to carry out research pro- grams on seamount ocean resources and ocean chemistry and climate in Hawai'i and the equatorial Pacific.

Jan 1, 1995

By Raymond A. Binns

The Eastern Manus Basin (EMB) contains three major active hydrothermal zones and a number of smaller occurrences of hydrothermal deposits, and can be considered as a regional-scale modern analogue for volcanic-hosted mineral fields on land. Unlike the central Manus Basin, a back-arc spreading zone with some MORB-like basalt-hosted massive sulfide deposits, the EMB is a pull-apart rift zone between two transform faults, where a basement of Eocene-Oligocene arc crust is being thinned by extension, with rapid sedimentation on the tilted fault blocks. Present-day submarine igneous activity in the EMB, with which hydrothermal activity is associated, has arc geochemical affinities and is related to subduction of the Solomon Sea Plate at the New Britain Trench. Overall, hydrothermal deposits in EMB are found with lavas ranging from picritic basalt to rhyodacite in composition, although the two major occurrences of massive sulfide are hosted by the more siliceous dacite and rhyodacite variants. Some volcanic edifices are central eruptions, mostly of porphyritic lavas or domes, while others are elongate ridges formed by fissure eruption in which the typically aphyric lavas were very fluid. Evidence for shallow-level fractional crystallisation controls of lava chemistry implies presence of subjacent differentiated intrusions or former magma chambers. Seismic tremor at one site during the nearby 1994 Rabaul eruption suggests magma movement in the chamber.

Jan 1, 1998

By H. I. Chesalova, M. Ye. Melnikov, A. M. Asavin

The discovery of iron-manganese ores on the surface of underwater mountains was made more than a half century ago. During this time the basic ideas about the thermodynamics of the processes of hydrochemical reactions in the sea water have been developed by scientists and are revealed in geochemical and mineralogical differences between the deposits from the seamounts and the nodules of the sea bottom. The distribution of the dissolved metals, oxygen, carbonic acid and organic matter in the overlying ocean waters of seamounts in the deep ocean to depths more than 5,000 m has been studied in some detail (e.g. J.R. Hein, P. Halbach. G.B. Baturin, Ye.M., S.I. Andreev, L.I. Anikeyeva, [1-6]). In recent years scientists from YUZMORGEOLOGY have completed detailed geological survey work on the Magellan Seamounts in the Pacific Ocean. The results of drilling the ore body and geophysical and photo surveys have also been described [4]. Previous ideas about the general covering of seamount surfaces with iron-manganese crusts have been changed based on ground-truth surveys. This study examines the complex concentric-zone or spotty arrangement of the most densely covered sections, the strong dependence of the thickness of crust on the geomorphologic features, and the potential influence of the underlying substratum. One established geochemical heterogeneity in the composition of ores, also frequently inversely proportional power dependence on directions was observed. The development of a numerical model of the formation of the ore crust on the seamounts is currently a high priority.

Sep 24, 2006

Clark volcano is a large volcanic center on the active arc front of the intraoceanic Kermadec arc. It is one of the two southern-most Kermadec arc volcanoes (the other being Whakatane volcano) that sits on oceanic crust before the transition to continental New Zealand, and is underlain by the 17-km-thick Hikurangi Plateau, which is presently subducting beneath the southern section of the Kermadec arc. Unusual K-rich basaltic lavas have been recovered from Clark (1.5 to 2.25 wt.% K2O), together with more typical basaltic-andesite, andesite and dacite rocks. The total volume of the Clark volcanic center is ~90 km3, calculated from the summit of the volcano down to the 2,500 m contour (which marks the inflection point of the volcano flanks with the surrounding seafloor) and comprises two separate edifices similar in size; the northern one having a volume of ~4.57 km3 and the southern one 4.43 km3. The volcano has a maximum relief of ~1,645 m from the 2,500 m contour to the summit of the shallower northern edifice shoaling to 855 m below sea level. The northern edifice is comprised of twin peaks each consisting of a constructional cone, with evidence of sector collapse having occurred between the cones. A more recent, smaller cone again has grown on the eastern flank between these summit cones. Massive, blocky lavas and coarse talus dominate the summits of the cones, with finer-grained volcaniclastic material and sediments a feature of the volcano flanks. The southern edifice is noticeably more dissected than the northern one, having a pronounced horst in the centre of the volcano bounded by 5-6 km-long faults. There is no obvious constructional cone atop the southern volcanic edifice.

Jan 1, 2011

By Jan M. Peter

The Early Norian Windy Craggy massive sulfide deposit is within the allochthonous Alexander terrane of the Insular tectonic belt in extreme northwestern British Columbia (Figure 1). Host rocks are the Middle Tats Volcanics, part of an informally-named volcano-sedimentary succession of mixed graphitic argillites and mafic pillowed and massive volcanic flows and sills of Upper Triassic age (Figure 2) that have suffered only lower greeschist-facies metamorphism. The volcanic rocks are light rare earth element (LREE)-enriched and display a variably developed back-arc subduction signature. Major and trace element compositions of the host argillite show that it contains an appreciable hydrothermal component, as evidenced by low high Fe and Mn contents. These sediments therefore record steady, continuous hydrothermal activity punctuated by intermittent turbidity currents sweeping into the basin. The deposit consists of at least two discrete sulfide lenses (the North and South Sulfide Bodies), as shown in Figure 3, a level plan at the elevation of the exploration workings. Published reserves at 0.5% copper cut-off are 297.4 million tonnes grading 1.38% Cu, 0.08% Co, 0.21 g/t Au and 3.9 g/t Ag (as of December 1991). However, the deposit is larger than this and further drilling is required to delineate it completely. Mineralization comprises massive sulfide, stringer/stockwork, and finely bedded to laminated sulfides and exhalites. Stockwork mineralization consists of sulfide-quartz-chlorite veins with attendant chlorite and silica alteration. Mineralization consists predominantly of massive pyrrhotite andlor pyrite with lesser chalcopyrite and magnetite. Figure 4 is an oblique section through the North Sulfide Body, the most northerly sulfide mass shown in Figure 3, which shows the distribution of the pyrite and pynhotite-rich massive mineralization and the stringer zone. The North Sulfide Body contains appreciable sphalerite, whereas the South Sulfide Body contains only trace amounts. Gangue minerals include quartz, chlorite, calcite, siderite, ankerite, stilpnomelane and magnetite. The minor hydrothermal exhalite sediments are comprised of chert, carbonate, and minor

Jan 1, 1993

By Peter M. Herzig

In September-October 2002, shallow seafloor drilling using the 5 m-Rockdrill of the British Geological Survey and the German R/V Sonne has revealed critical information on the sub-surface nature of two distinct hydrothermal systems in the New Ireland fore-arc and the Manus Basin of Papua New Guinea. Drilling at the summit plateau of Conical Seamount (39 holes, 31 % recovery) south of Lihir Island in the central New Ireland fore-arc has confirmed the sub-seafloor extend of previously discovered surface gold mineralization (up to 230 g/t Au) and associated alteration to a depth of at least 4.5 m below the seafloor and further proven analogies to the giant Ladolam epithermal gold deposit on Lihir Island. Drill core samples of clay-silica alteration contain average gold grades up to 14.2 g/t Au over a length of about 30 cm (fire assay Lihir Gold Ltd. laboratory) and appear to be part of a more extensive gold zone located below a carapace of relatively fresh ancaramitic and trachybasalt. These samples contain a complex mineralogy including realgar, orpiment, galena, sphalerite, some chalcopyrite and pyrite, together with amorphous silica, and possibly cinnabar. In addition to high concentrations of gold, shipboard analyses indicate that the gold-rich samples contain high values of Pb, As, and Sb, which is a characteristic feature of a magmatic-hydrothermal style of mineralization and alteration.

Jan 1, 2002

By Robert G. Ditchburn

Msjflkcisokng During the past sixteen years, GNS Science has developed a number of radiometric methods for dating massive sulfide samples from submarine arc and back-arc volcanoes. This has improved our understanding of the formation of these hydrothermal systems, the frequency and duration of their activity, and assisted marine mineral exploration companies in assessing the economic potential of these deposits that can be rich in copper, zinc and gold (up to 90 ppm Au in some chimneys). The radiometric dating methods that we employ utilize radium isotopes that are extracted from the host rocks without their parent thorium isotopes, by ascending, hot, acidic hydrothermal fluids. When the hydrothermal fluid discharges into cold seawater, chemically similar barium and radium co-precipitate as barite, a common mineral contained within the black smoker chimneys that grow upwards from the seafloor. From the onset of mineralization, the isotopes 228Ra and 226Ra (with half-lives of 5.75 yrs and 1600 yrs, respectively) begin to decay, so that the 228Ra/226Ra and 226Ra/Ba values decrease with time. Thus, samples can be dated using these ratios once the initial values, i.e., the values at the onset of mineralization, have been established, ideally from active chimneys. 228Ra decays to 228Th (half-life 1.91 yrs) and from the 228Th/228Ra values, the growth-rate of individual chimneys can be estimated. The isotope 210Pb (half-life 22.3 yrs) is occasionally used for dating the mineralization, although several samples from a chimney are needed to determine an age from the 210Pb grown from 226Ra, using the isochron technique.

Sep 14, 2011

By Sup Hong

A pilot mining robot, named MineRo-II, has been developed by KIOST during 2011-2012. The pilot scale was defined as 1/5 of the commercial mining capacity, 1.5 million dry-tons of nodules per year. The development purpose of MineRo-II is to use for the pilot mining test planned in 2015. MineRo-II was designed to be self-propelled by electric-hydraulic power and remotely operated in real-time from aboard. The main operational functions are crawling on seafloor, pick-up and crushing of nodules, discharging nodules out to buffer. Prior to MineRo-II, a test miner (MineRo-I) was developed in scale of 1/20th in 2007, and performed two times sea trials in 2009 and 2010. The results of performance tests were evaluated and utilized for the concept of MineRo-II. The design concept aimed at the expandability of the mining capacity based on modularity of configuration, maintenance simplicity and multiplicity of backup solution. The pilot-scale mining capacity is achieved by four pick-up modules of each 1m wide, which are moving forward with robot vehicle and sweep the nodules entering below the pick-up heads. Principally, by adding the pickup modules in lateral dimension the mining capacity may increase linearly. MineRo-II was designed and constructed in unit-module wise. The robot consists of two unit-modules having an identical mechanical and hydraulic configuration. Each unitmodule has two tracks, two pick-up devices with attitude control devices, two crushers, one discharge pump, and one hydraulic system. Two unit-modules are connected by one loading frame and integrated by electric-electronic system. Two thrusters for control of the

Sep 14, 2011

By I. Yu. Melekestseva, V. V. Zaykov

Paleooceanic structures of the Urals fold belt contain different volcanic-hosted massive sulfide deposits of the Urals, Kuroko and Cyprus types [Prokin, Buslaev, 1999]. Small Cobearing massive sulfide deposits, as Ishkinino, Ivanovka and Dergamysh, associated with ultramafites of the Main Urals fault, are less known. Interest to them had arisen after discoveries of the modern “black smokers” associated with ultramafic rocks of the Middle-Atlantic Ridge (MAR). Ores of the Urals deposits are enriched in Co (0.3 %) and Ni (0.6 %) that are concentrated in Co-Ni-Fe-sulfides, sulfarsenides, and arsenides. Ores also contain the increased gold contents – 3–6 ppm and up to 16 ppm in those saturated with As-bearing minerals. The aim of the paper is a comparison of precious metal mineralization in ores from the Paleozoic and modern ultramafic-hosted massive sulfides.

Aug 24, 2006

By D. S. Cronan

Studies on polymetallic manganese nodules and Co-rich crusts in the EEZ's of the Cook, Line, Ellice and Phoenix Islands between 0-20°S show that Ni and Cu reach their greatest combined abundances of over 2% between 2-8°S on the southern margin of the equatorial zone of high biological productivity, as a result of biological fluxing of Ni and Cu to the nodules at and just below the CCD. By contrast, Co reaches it greatest abundance of 0.6% south of 8°S in nodules on non-biogenic clays well below the CCD where little biological Co supply is likely. Nodule abundances are greatest (up to 30kg/m2) in the Co-rich area in part due to AABW flow, giving highest overall metal quantities per sq meter in the nodules there, particularly of Co. There are approximately 110 x 106 tonnnes of combined Ni plus Cu plus Co expressed as Ni equivalent in Cook Islands EEZ nodules, approximately 12 x 106t. in Phoenix Islands ones, and approximately 1.4 x 106 t. in Ellice Islands ones, in areas of greater than 5kg/m2 nodule abundance. In the Co-rich crusts, Co averages about 0.7% and crust thickness about 1.6cm, both related to metal fluxes in and adjacent to the 02 minimum zone in association with which both maximum thicknesses and Co grades occur. Within the Cook Islands permissive area there are about 930 x 103 t. of Co and 630 x 103 t. of Ni in crusts, in Phoenix Islands crusts there are about 69 x 103 t. of Co and 55 x 103 t. of Ni, and in Ellice Islands crusts there are about

Jan 1, 1989

By I. Yu. Melekestseva

The Semenov hydrothermal sulfide cluster (13º31´N), consisted of five fields (Semenov-1, -2, -3, -4, and -5), was discovered in 2007 in the 30th cruise of R/V Professor Logatchev [Beltenev et al., 2007; 2009]. The hydrothermal fields are located on a seamount composed of ultramafic and mafic rocks, gabbro, plagiogranite, and their altered rocks. The Semenov cluster is considered to be the largest sulfide accumulation in the Ocean with massive sulfide (MS) resources of about 40 million tons [Beltenev et al., 2009]. MS of the Semenov-1, -3, -4, and -5 hydrothermal fields are mostly characterized by marcasite-pyrite composition whereas rich copper-zinc MS with high Cu and Zn contents (11.37?19.33 and 5.89?18.32%, respectively) and anomalous Au and Ag grades (22?188 ?127?1787 ppm, respectively) were dredged only at the Semenov-2 hydrothermal field associated with basalts (13°31.13´N, 44°59.03´W; 2360?2580 m of depths) [Ivanov et al., 2008].

Jan 1, 2010

By Peter M. Herzig

In 1994 and 1998 the German research vessel R/V Sonne undertook detailed mapping and sampling of the largely uncharted offshore areas of the Tabar-Lihir-Tanga-Feni island chain in the New Ireland Basin of Papua New Guinea. The New Ireland Basin occupies a fore-arc position with respect to the formerly active Manus-Kilinailau arc-trench system and hosts a series of Pliocene to Recent alkaline volcanoes which are built on rifted Miocene sedimentary basement. Several of the volcanoes possess high-level porphyry stocks and active geothermal systems, including gold-depositing hot springs and the giant (40 million ounces) Ladolam gold deposit on the island of Lihir. On the southern flank of Lihir island, a group of three volcanic cones were discovered at water depths from 1.000-1.500 m. The volcanoes are located in a narrow zone of recent seismic activity and elevated heat flow (up to 100 mW/m2). The recovered volcanic rocks consist of fresh alkali-olivine basalts, clinopyroxene-rich basalts (ankaramites), porphyritic phlogopite basalts, and trachybasalts. Unusual gold-rich hydrothermal precipitates were recovered from the summit of the 600 m high Conical Seamount located only about 10 km south of Lihir Island. 1200 kg of sampled material systematically collected with a TV-guided grab from the top plateau (150 x 200 m, 1.050 m water depth) are intensely mineralized with pyrite, marcasite, minor sphalerite, chalcopyrite, galena, tennantite/tetrahedrite, and orpiment/realgar together with traces of anglesite, cerrusite, and amorphous silica in stockwork-like veins. Bulk samples of the vein mineralization consist mainly of clays, silica, and disseminated sulfides, and have an unusual high gold content ranging from 1.2-44.0 ppm Au. In some of these samples, grains of native gold (about 1 micron in diameter) were identified by SEM in pyrite and sphalerite. The gold-rich material also contains high concentrations of silver (up to 1000 ppm) and typical epithermal elements such as As (2.6 wt.%), Sb (0.2 wt.%), and Hg (34 ppm). Similar to epithermal deposits on land, which usually have only low base metal contents, the samples from Conical Seamount contain only minor amounts of Zn (max. 4.5 wt.%), Cu (2.0 wt.%), and Pb (2.0 wt.%). Many of the samples recovered from Conical Seamount are virtually identical to the gold ore at Lihir.

Jan 1, 1998

By Charles L. Morgan

"In 2012 the International Seabed Authority (ISA) established nine “Areas of Particular Environmental Interest” (APEIs) for consideration as future Marine Protected Areas to help preserve the biodiversity of life on the seabed within the Clarion-Clipperton Zone (CCZ) between Baja California, Mexico, and the Hawaiian Islands. The CCZ is believed to have a high potential for future seabed mining operations. Areas under active exploration contracts in the CCZ, plus the areas currently reserved by the ISA for exploration by developing nations, comprise about 1.9 million km2 of seabed area. The currently designated APEIs consist of more than 1.4 million km2 of seabed. Each APEI includes a central primary conservation area of 200 X 200 km, surrounded by 100-km buffer areas on all sides. The 100-km buffers are intended as a very conservative spacing between the primary conservation area and potential mining activities in adjacent seabed. The selection of these nine 400 X 400 km APEIs, has been criticized as possibly not including sufficient representative habitat similar enough to the potential mining areas (identified currently as the exploration contract and reserved areas administered by the ISA within the region) to ensure protection of the biodiversity that might be impacted by mining.An area to the east of the existing exploration contracts and reserved areas is known to have substantial mineral deposits; it is very similar to the adjacent exploration contract areas in its geology, environmental setting, polymetallic nodule abundance and nodule metal content. Because it is located in the northeastern extreme of the CCZ, this area is also likely to have relatively high densities of benthic life, compared with benthic communities further westward within the CCZ. Many options for the designation of this APEI are possible, but the area designation must accommodate the boundaries of the Exclusive Economic Zones of Mexico and France.This paper discusses why the selected region in the eastern extreme of the CCZ is a good candidate for designation as a new APEI.Keywords: polymetallic nodules, Marine Protected Areas, Clarion-Clipperton Zone, Areas of Particular Environmental Interest"

Jan 1, 2017