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By S. Kim Juniper

The discovery of chemosynthetic-based ecosystems at hydrothermal vents in the deep ocean was arguably one of the most important findings in biological science in the latter half of the 20th century. More than 100 vent fields have been documented along the 60,000 km global mid-ocean ridge system. Over 500 new animal species, over 80% of which are endemic to the vents, have been described from this environment. Unusual, highly evolved symbioses between invertebrates and chemolithautotrophic bacteria are common at vents, producing concentrations of biomass that rival the most productive ecosystems on Earth. Hydrothermal vents ecosystems, because of their very limited area and the presence of endemic species, are highly vulnerable to human disturbance. Mining for polymetallic sulphide deposits poses the greatest future physical threat to hydrothermal vents and their biological communities. However, there is more immediate concern about the impact of concentrated scientific research activities. Some sites have been revisited by several research expeditions per year for more than a decade. As vent sites become the focus of intensive, long-term research, oversight organizations are discussing mitigative measures to avoid significant loss of habitat or oversampling of populations. Canada recently became the first national jurisdiction to set aside a hydrothermal vent site as a Marine Protected Area.

Jan 1, 2001

By Valcana Stoyanova

Data and information for this study were collected in June-July 2009 onboard the RV Yuzhmorgeologiya in the area covers about 7000 km2 in the eastern part of the CCFZ between 10º05? - 10º55?N and 119º25? ? 121º08?W. In accordance with the IOM research program the cruise was intend to acquire both geological and environmental data and information necessary for delineation of nodule deposits and also data for identification of the baseline of benthic ecosystem. Having implementation of its 15-year plan of work for exploration under the contract with ISA, current activities of IOM were focused on nodule fields within prime areas that could be mined in the future. Bottom photographs obtained by towed deep-sea vehicle NEPTUN along 6 profiles with common length about 300 km (Fig. 1). In total, about 11,500 digital photographs (what cover approximately 40,000 m2 of the ocean floor) were analyzed for assessment of nodule coverage and investigation of megafauna (animals, visible in photographs, the dimension more than 2 cm). The giant single-cell organisms Xenophyophorida were the most multiple animals in seabed photographs. Their number on the site area averaged 1187 ind/ha. However, the vertical camera position does not allow counting all xenophyophorids, therefore their valid number is represented 10 times more. According to all available information these protozoans play the relevant role in assemblage of deep-water environment, giving for other animal groups an [ ] additional source of nutrition and a substratum for settlement and attachment. The ophiuroids are found in assemblage with xenophyophorids in many cases, standing on a sediment at their base.

Jan 1, 2010

By A. Ivanova

The continental shelves occupy a vast area of Russia and contain complexes of commercial placer minerals. Of prime importance are Cenozoic placers of valuable minerals including gold, cassiterite, diamonds, chromite, platinoids, and minerals of titanium, zirconium and rare earth elements, biogenic amber and fossil ivory (1). Commercial placer minerals are associated with shelf placer formation zones (SPFZ). These zones are located at junctions of marginal orogens and shelf troughs in morphostructures where upwarping, subsidence, and sign-variable neotectonic movements are not significant. The SPFZs are characterized by ancient buried leveling planes with mantles of waste, series of wave-cut aggradation terraces on land and beneath the sea, and drowned and buried stream valleys. The occurrence of mineral placers in the SPFZs was caused by endogenic mineralization and exogenic placer hosted formation. Concentrations of commercial biogenic minerals are associated with areas of burial of biogenic material (release of resins by plants and theriofauna thanatocoenoses) and with their transition zones. Since the Oligocene, alternations in marine transgression-regression have dominated the shelf areas. This has resulted in the formation of polygenic placers. Climatic conditions are of great importance: warm and humid climate in the Paleogene-Neogene changed to colder climates in the late Pliocene (polar type sedimentation; formation of permafrost strata and sea glaciation). These events are responsible for the regularity in placer formation during the Cenozoic in which the early Cenozoic (Eocene-Oligocene-Miocene) and late Cenozoic (late Pliocene-early Pleistocene and late Pleistocene-Holocene) epochs are prominent.

Jan 1, 2004

By Andrew G. Hudson

The long-term economics of each of the four principal metals in marine manganese nodules (copper, nickel, cobalt and manganese) was evaluated to determine the anticipated viability of a nodule mining venture based on existing studies of the potential profitability of a nodule project. This included assessments of the lifetimes of land-based reserves, and examination and econometric modelling of the economic variables thought to affect nodule metal prices and demand. These analyses demonstrated that a) land-based reserves of the nodule metals were likely to last well into the future (100 400 years); b) average nodule metal paces were likely to stay a low levels for the foreseeable future; and c) the expected revenue stream from a twenty- ear nodule mining venture was substantially (42%) below that required to attract the necessary investment capital for such a high risk venture.

Jan 1, 1996

By Porter Hoagland

It is well known that significant quantities of mineral deposits exist in the oceans. Most of these resources cannot yet be classified as economic "reserves" in the strict sense of the term, but they serve as backstops to deposits of identical minerals produced onshore. The prospects for the commercialization of ocean mineral resources will depend upon factors affecting both supply and demand, including, among other things, changes in consumption patterns, technological developments, new discoveries, developments in markets for complements and substitutes, and environmental regulation. In this presentation, we examine broad trends in mineral prices, as one of the most summary measures of the prospects for the commercialization of ocean minerals. Further, we report on any recent developments in the relevant product markets that may affect the potential for commercialization.

Jan 1, 1996

Ancient volcanogenic Cu-Zn-Pb-Ag-Au massive sulfide ores commonly have associated with them along strike and in the immediate hanging wall a distinctive sediment that is thin, usually cherty and metal enriched, and generally referred to as an "exhalite horizon" or "tuffaceous exhalite". Typical examplks include the 13 Ma tetsusekiei of the Kuroko deposits of Japan (Kalogeropoulos and Scott, 1983, Econ. Geol.) and the 2700 Ma contact tuffs of Noranda, Canada (Kalogeropoulos and Scott, 1989, Can. J. Earth Sci.) and Key Tuffite of Mattagami, Canada (Liaghat and McLean, 1992, Explor. Min. Geol.). Attempts to use trace element distributions as lithogeochemical guides to ore have been largely unsuccessful. Exhalites have been considered to be the products of seafloor hydrothermal activity that is peripheral to the main ore-producing vents. However, large actively-forming polyrnetallic sulfide deposits at the Explorer mid-ocean basalt spreading ridge (1 850 m depth) in the NE Pacific and the eastern Manus back-arc dacitic spreading center (1650 m depth) in the western Pacific have demonstrated that the exhalite horizons are more likely produced by fallout of particulates from the main hydrothermal plume. In a typical hydrothermal plume, grains of >27 µm represent up to 97% of the mass (although only 2% of the population) of the particulates and are calculated by Stokes equations to fall from the plume to the seafloor within a few krn of their source. The particles are primarily composed of anhydrite, barite, amorphous silica, iron oxyhydroxides and metal sulfides and oxides. Plumes are subject to bottom currents which push them in preferred directions, just like smoke plumes in the atmosphere are subject to the vagaries of wind direction. Bottom currents in the deep ocean can be 50 m/min or

Jan 1, 1993

By Georgy A. Cherkashov

Two principal types of the hydrothermal fields in Atlantic - axial and off-axis - could be established based on their structural setting in the rift zone of the Mid-Atlantic Ridge (MAR) (Figure1). The first (axial) type is represented by five high- and three low-temperature hydrothermal sites (Table 1). All of these fields are connected with young axial effusive volcanism and related to large linear volcanic ridges or central volcanoes at the inner floor of the rift valley. The hydrothermal activity here is controlled by the intersection between longitudinal magma feeding faults and transverse weakened zones characterized by high permeability. [ ] The hydrothermal sites of the second (off-axis) type (such as Rainbow, TAG, 24°30?N, Logatchev, newly discovered 13°N (Figure 2) and possibly 16°48?N sites) are related to large tectonic dislocations forming marginal scarps of the rift valley as well as transverse discontinuities.

Jan 1, 2003

By Wilhelm Schwarz

Manganese nodules lay in vast areas of the deep sea floor. Ideal harvesting conditions for a manganese nodule field are dense nodule abundances of nodules between 20 and 60 mm diameter and a metal content as high as possible. With regard to the development of collector technology, the properties of the deep sea soil, in which the nodules are embedded and to which the nodules stick, are of major interest. The forces for loosening the nodules have to be provided by the collector. For this purpose water jets and/or mechanical devices can be employed. For the choice of the best collecting procedure, various criteria, such as collecting rate, energy consumption and the environmental impact on the eco system of the deep sea floor, have to be considered and weighted as to their importance. Nowadays, the concept of a mining system with a flexible transport hose and a self propelled collecting machine is increasingly accepted among the expert community. With regard to the trafficability of the deep sea soil with a self propelled mining machine, the mechanic properties of the soil and the morphology of the deep sea floor are of special importance. The manganese nodule fields, which are interesting with regard to their recoverability, are mostly in the areas of tectonic fracture zones, at which the morphology of the sea floor is formed by vulcanic activities. In these areas, deep sea mountains, pits and other obstacles exist that have to be driven around if not trafficable.

Jan 1, 2003

By Valery M. Yubko

"The conceptual basis of the developed model is based on the ideas that evolution of geological-geomorphological structure of the CCZ is controlled by four types of geologic factors: geodynamic, sedimentary, volcano-tectonic and erosion-lithodynamic. In terms of time span two factors (geodynamic and sedimentary) can be considered as permanent and the other two as sporadic.The geodynamic factor is responsible for two interrelated geological processes. One is going under conditions of the axial zones of spreading centers and results in formation of the CCZ basement. Historically this process is considered as a starting point for each of the heterochronous fragments of the CCZ. The second one controls gradual shifting towards the Pacific Plate (Hawaiian direction) and subsidence to greater depths of the neogenic fragments (basement). Thus, those processes control basic topography, geomorphology and the seabed depth within the CCZ.Volcanogenic-hydrothermal activity of the EPR is one of the main sources of the ore components, which finally compose manganese nodules as a result of complicated processes of their dissemination and transportation to the bottom in dissolved and organically bound forms.The role of the other constant factor (sedimentary) is displayed in two ways. Firstly, initial relief is smoothed under the influence of this factor, which, subsequently, makes favorable conditions for manganese nodules formation. Secondly, it favors transportation of the majority of the ore components, participating in manganese nodules formation into zones of active nodules formation."

Jan 1, 2017

By Cheng Xiangzhou

The China's Pioneer area includes two parts. The topography in the western part is very different from that in the eastern one. The distribution of the manganese nodules in these two regions differs correspondingly China Ocean Mineral Resources Research and Development Association (COMRA) will take appropriate measures so that the next development will be adapted to the features of its potential minable area.

Jan 1, 1996

By V. Zaykov

The Urals massive sulfide deposits are concentrated in Silurian -Devonian fold belt extending for 1500 km with length from 50 to 150 km. By paleodynamic reconstmction it is established that they were formed in submarine parts of island arcs, in inter arc and back arc basins, marginal seas. When "black smokers" were found in rift zones of present oceans, problem searching their analogues in the Urals Paleozoic complexes was arisen. For solving this problem and demonstration of seafloor origin of massive sulfide many quarries and drill cores were carefully sketched and studied. Particular attention was given to correlation between ores and synchronous sedimentary rocks and fossils. Various laboratory methods were used for comparing sulfides from ore hills with ore-clastic sulfides.

Jan 1, 1993

By S. Rajendran

Much advance has been made in offshore hydrocarbon exploration and exploitation in India. But the same amount of success could not be achieved in the case of other offshore minerals which are amenable for mining. However, employing present technology, there should not be any difficulty in successful exploitation with minimum environmental hazards. A demonstration is provided by considering the conditions prevailing in the Kerala offshore (southwest coast of India) scenario of monazite, ilmenite, phosphatic mud and calcareous deposits. Mud banks are unique phenomenon of the Kerala coast during monsoon season. Acting as barriers to waves, mud banks protect portions of the beaches from being eroded and trap sediments from either side facilitating growth of adjacent beach. The easy minable possibilities of the phosphatic mud during non-monsoon season with less pollution hazards and dumping back the waste material after processing for phosphate at the breaker zones to reduce the erosional effects on the coast make the exploitation economic and ecofriendly unlike the benefication of the lowgrade phosphate ores on land on a comparatively larger area and subsequent crushing, transport and resulting pollution.

Jan 1, 1993

By Yannick Beaudoin

The source of base metals in modern seafloor hydrothermal systems can be attributed to leaching of host rocks by hydrothermal fluids and/or potentially by direct degassing of magma. From an economic perspective, metal grade is the most important consideration for seafloor deposits. Tectonic setting appears to be a key factor influencing the development of high grade seafloor base metal sulfide deposits. Back-arcs have a clear advantage over other settings in producing large and rich polymetallic sulfide ores. Microinclusions of magma or so-called melt inclusions trapped in phenocrysts of lavas have contributed to our understanding of the ore-forming process. n this study, we present data from 103 melt inclusions mainly in plagioclase crystals hosted in basaltic to rhyolitic lavas from 9 modern seafloor tectonic settings: oceanic back-arcs (Manus Basin including an ODP Leg 193 drill hole, Bransfield Straits), continental back-arc (Okinawa Trough), mid-ocean ridges (Explorer, MAR), seamounts (Foundation, Axial, Pito), and a transform (Garrett). Most sites host active hydrothermal systems that are producing polymetallic sulfides.

Jan 1, 2005

By Roy Nilsen, Aravinda Perera

With the exponential growth of demand for minerals and need for diversification of supply channels, deep-sea mining is rapidly becoming inevitable. Productivity of underwater mining technology is salient to justify the deep-sea explorations. Methods for enhanced productivity of mobile mining equipment in a system level are investigated in this paper. Lessons learnt from the land-based mining has been the basis of this investigation. In general, mining productivity can be enhanced in two ways; firstly, by maximizing the amount of recovered material per unit time and secondly, by minimizing the cost of operation per unit material. Equipment that enable faster excavation, loading and transport in the seabed contributes significantly in increasing the amount of slurry per unit time. Improved mean time between failures (MTBF) of mining equipment will reduce the operational down time, thereby, contribute to maximize the amount of mined material per unit time. Several factors influence the operational cost minimization per ton of slurry. Higher efficient motor drive systems including the motor and PWM-fed inverter not only will save power but also will emit lesser heat thus the heat management can be less complex. This leads to more compact drive systems that allows higher power density, thus increased payload weight per empty vehicle weight. An energy storage method in the form of an utracapacitor in the electric drive system will also save the energy supply from the upstream.

Jan 1, 2018

By Katsuya Tsurusaki

Commercial mining of manganese nodules is expected to begin within the next 20 to 50 years in large areas of abyssal sea floor in the Pacific Ocean. While deep sea mining is expected to realize significant quantities of rare metals that are needed for modern technology, the mining operation will cause extensive resedimentation over large areas of deep sea floor, the effects of which are thought to be harmful to the benthic community. Our present knowledge of deep sea benthic ecology is so limited that we cannot predict the magnitude of the impact. In November 1994, the United Nations Convention on the Law of the Sea was enforced and giving added impetus to improving our understanding of the effects of future mining operations. In order to fully understand the impact of deep sea mining and to mitigate the harmful environmental effects, it is necessary to accumulate more information on the deep sea environment and benthic communities. To achieve these objectives and to understand the relationship between resedimentation and biological reaction, artificial impact experiments are being conducted by the USA and Germany. The former named BIE (Benthic Impact Experiment) began in 1991 and is being performed by NOAA (National Oceanic and Atmospheric Administration of the United State of America) in the North Equatorial Pacific Ocean. The latter named DISCOL (Disturbance and Recolonization Experiment in the Deep South Pacific Ocean) was started in 1989 and is being conducted in the South Equatorial Pacific Ocean by a scientific group from Hamburg University. The Metal Mining Agency of Japan (MMAJ) is also carrying out environmental studies. These studies, commenced in 1989, are being conducted in association with NOAA and include an experiment named the Japan Deep Sea Impact Experiment (JET).

Jan 1, 1996

By Akira Usui, Sayuri Kubo, Satoshi Tokeshi, Shingo Kato, Katsuhiko Suzuki, Teruhiko Kashiwabara

"INTRODUCTIONFerromanganese (Fe-Mn) crusts are a kind of marine chemical sediment composed of Fe and Mn oxy-hydroxides as well as small amounts of clastic sediments, which are ubiquitously found on the surface of slopes of seamounts and oceanic plateaus at depths from 900 to 5500 meters below sea level (mbsl). Fe-Mn crusts contain extremely high concentrations of useful minor metals such as Co, Ni, Te, REEs, and thus are expected as submarine mineral resources. Also, Fe-Mn crusts record the change of chemical compositions of seawater during last several tens million years, which allow us to obtain clues to clarify the paleoenvironmental conditions at the time of its deposition. However, occurrence, chemical compositions, microbial community and growth patterns of ferromanganese crusts are yet fully understood. Hence, a comprehensive study on the genesis of ferromanganese crusts, such as growth rates and enrichment processes of elements, is required to better understand their resource potential as well as their applications to paleoceanographic study.Based on the resource potential of ferro-manganese crust, the project entitled “Next- Generation Technology for Ocean Resources Exploration” was launched as one of the governmental projects to develop the exploration technology based on the scientific research on the submarine resources such as hydrothermal deposits (e.g., a poster by Kawada et al.), ferro-manganese crusts. We have made several research cruise to seamounts in the north-western Pacific such as Takuyo-Daigo and Takuyo-Daisan seamounts (Fig. 1) ."

Jan 1, 2017

In the western Woodlark Basin, propagation of seafloor spreading is occurring directly into the continental crust of Papua new Guinea. The spreading is not strictly in a back-arc tectonic setting, rather it appears associated with microplate rotations related to the complex convergence of the Indo-Australian and Pacific plates in the southeastern Pacific region. Volcanic rocks along the western Woodlark spreading axis range from normal mid- ocean ridge basalts to basaltic andesites with back-arc geochemical affinities. Rare peralkaline rhyolites also occur. Hydrothermal deposits occur at a basaltic andesite volcano located on the neovolcanic zone near its westernmost propagating tip. Franklin Seamount is a 250m-high cone constructed largely of pillow lavas and talus which sits astride a 450m-high ridge of similar lavas oriented subnormal to the spreading direction. At its crest, 2150m below sea level, there is a 100m-deep caldera.

Jan 1, 1993

By Samantha Whisman, James R. Hein

Hydrothermal marine manganese-oxide deposits (HMMD) are cemented and variously replaced volcaniclastic and biogenic sediments that were mineralized by distal, low- temperature, hydrothermal fluids. HMMD predominantly form below the seabed as sediment-hosted statabound deposits but can also form on the seabed. These deposits form at oceanic and back-arc basin spreading centers, volcanic arcs, and mid-place hotspot volcanoes. HMMD have traditionally not been considered to have an economic potential because they were considered to be devoid of economically valuable critical elements. This contrasts with their non-hydrothermal counterparts, ferromanganese crusts and nodules, which are enriched in many critical elements. However, manganese is now one of the critical metals and HMMD have the highest manganese contents (up to 55% Mn, so- called battery-grade Mn) of all the types of deep-ocean mineral deposits. There is a growing demand for this critical metal and an upward trend exists in the price of manganese on the global market. Also, other critical elements can occur in high concentrations in some HMMD and their economic potential has not been considered, especially for lithium (up to 0.17%) and molybdenum (up to 0.24%), but also vanadium (to 820 ppm), chromium (to 346 ppm), and nickel (to 0.45%), among others. Which of these critical elements are enriched and their concentrations depend on the types of rocks leached at depth by the hydrothermal fluids, the composition of hydrothermal minerals precipitated in the higher temperature parts of the circulation system, and the types of sediments mineralized by the manganese oxides. For example, mineralization of a carbonate sediment resulted in the highest lithium contents, whereas leaching of ultramafic rocks at depth as a rule results in the highest chromium and nickel contents in the HMMD. These deposits are known to be widespread, especially in volcanic arcs, but their lateral and vertical extents and consequently size, tonnage, and grade have not been determined. Most samples of hydrothermal deposits have been collected by dredging and therefore the in situ relationships often are not known. One sample from the Mariana volcanic arc, west Pacific, was collected by ROV at 1274 m water depth from a layered outcrop 6.6 m thick that may be a sequence of pervasively mineralized volcaniclastic layers and offers the first clue as to the potential vertical extent that these deposits may attain. However, only the top ~0.4 m-thick layer was sampled, so it is not known whether the mineralization extents throughout the outcrop. Although large manganese deposits of various origins occur on the continents, they consist of manganese carbonates, silicates, or complex mixtures of manganese minerals. In contrast, marine hydrothermal HMMD exhibit relatively simple mineralogy that would make processing of this potential ore much simpler.

Jan 1, 2018

By J. R. Woolsey

The cost of an offshore exploration project is mainly dependent on the size of the vessel engaged for the work and increases dramatically with increasing size. Of the various factors influencing vessel size, the type and size of the sampling equipment is typically the principal consideration. This scenario is particularly true of shallow sampling programs employing a vibracore system. The problem develops when certain bottom materials such as densely packed fine sand require sampling. This type of material being one of the most difficult for the standard vibracore systems, with integral core liner, to penetrate to a reasonable depth of some five to seven meters. The problem is mainly related to the excessive cross sectional area of the cutting bit required to accommodate the core liner. The typical solution has been to apply more power to the vibracore drive head which results in a considerable scale-up for the entire system with attendant increase in vessel size. In order to reduce operating cost, M.M.R.I. has developed several systems for deployment from vessels in the 20 meter range. Two systems are modifications to the basic vibracore and a third is a vibralift system. Basically, one of the vibracore units is employed where core liners are required, utilizing a special jet bit designed to reduce the cutting pressure on the bit while not affecting the integrity of the core. The other designed for core extrusion on

Jan 1, 1986

By Robert M. Owen

Geochemical exploration for marine placers involves the acquisition, processing, and interpretation of geochemical data. Recent technological advances such as in-situ analysis systems and microcomputers have greatly improved our ability to acquire and process data, but their full benefits cannot be realized until we also develop improved methods for reducing and interpreting large amounts of raw geochemical data. Toward this end, our research has sought to identify existing and/or develop new geostatistical techniques for use in marine placer exploration. Each technique has been tested by evaluating its performance in the analysis of existing data sets. The data sets typically include the results of chemical analyses of suites of sediment samples collected from areas of known or suspected platinum and gold placers along the Bering Sea coast of Alaska. Results to date indicate that three geostatistical methods (subpopulation partitioning analysis, comparative factor analysis, and end-member compositional factor analysis) are useful in identifying elemental groups which can serve as "pathfinders" in the search for marine placers, and are also helpful in discerning the generic geochemical basis under lying observed statistical correlations between pathfinder elements and placer minerals. Existing methods of modelling sediment dispersal patterns have been examined with a view toward adapting them to the specific problem of understanding placer formation in

Jan 1, 1986