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By Tobias Hens, Andrew Frierdich, Barbara Etschmann, Joël Brugger, Barrie Bolton

"Advancing our knowledge about trace metal distribution and abundance provides insight into formation, alteration, and trace element enrichment processes of ferromanganese nodules and crusts. A fundamental understanding of these mechanisms, in turn, has implications for the selective recovery of critical metals and the development of sustainable hydrometallurgical techniques. Synchrotron-based X-ray Fluorescence (SXRF) is a powerful, state-of-the-art analytical tool that can examine geochemical features of Fe-Mn nodules and crusts, such as abundance and distribution of trace elements, in an integrated and efficient manner. By correlating trace element composition and Mn oxidation states in these highly complex samples, it can be determined whether these parameters are related to the Mn oxide mineralogy (vacancy content of crystal lattice) and chemistry.In this study, eleven Fe-Mn nodule and crust samples from three circum-Australian locations – the South Tasman Rise, Lord Howe Rise, and Coral Sea – were analyzed at the Australian Synchrotron, Victoria, Australia. Micrometer-scale spatial resolution of geochemical features, such as concentric growth structures and element distribution, was achieved with high sensitivity (Fig. 1). For instance, Ni could be detected at 10's of ppm to 1 wt% levels. Information on other redox-sensitive trace elements, which are present at 10-1000 ppm levels (e.g., Cu, Co, Ti), were gained by means of fully quantitative elemental composition maps."

Jan 1, 2017

By Cornel E. J. de Ronde

Brothers volcano (34°51.7?S, 179°03.6?E) is a large caldera volcano that forms part of the active Kermadec arc south of 32° S, NE of New Zealand. It is an elongate edifice striking NW-SE that is ~11-13 km long by 7-8 km across. The caldera has a basal diameter of 3-3.5 km and is surrounded by 350-450 m high walls with the floor 1,850 m deep. A volcanic cone of dacite composition rises 350 m from the caldera floor and partially coalesces with the southern caldera wall. Much of the caldera construction and the location of the hydrothermal vent sites are controlled by intersecting basement structures. Three hydrothermal sites have been recognized at Brothers; NW caldera, SE caldera and cone. Multiple hydrothermal plumes were mapped from the bottom of the caldera upwards to a depth of 900 m and originate from two of the sites; one on the NW caldera wall the other atop the cone. Analyses of these plumes show that the two vent sites are chemically distinct. The cone site itself hosts three distinct vent fields (summit, upper flank, NE flank) that in 1999 had plumes (mainly from the summit) containing relatively high concentrations of gas with a shift of -0.27 pH units (proxy for CO2) and H2S concentrations up to 4,250 nM, particulate Cu (PCu) of 3.4 nM, total dissolvable Fe (TDFe) of 4,720 nM, TDMn up to 260 nM and Fe/Mn values between 4.4 and 18.2. However, in 2002 plumes from the summit vent field had noticeably lower concentrations of PCu (0.3 nM), TDFe (175 nM), and Fe/Mn values of 0.8, although similar TDMn (220 nM) and shift in pH (-0.22) suggesting a state of flux for this site. By contrast, plumes originating from the NW caldera site have much less gas with a pH shift of -0.09 units and no detectable H2S, TDFe up to 955 nM, TDMn up to 150 nM, and Fe/Mn values of 6.4, and have not changed their composition over the same three year interval indicating a more chronic hydrothermal system. Plume d3He results show helium is decoupled from more near-surface vent fluid sources although a shift in R/Ra values from 6.1 ± 0.5 in 1999 for the combined vent sites to 7.2 ± 0.1 in 2002 indicates a less radiogenic input of helium over three years, suggestive of a greater magmatic input to the system.

Jan 1, 2004

By Natalia Konstantinova, Kira Mizell, James R. Hein, Georgy Cherkashov, Amy Gartman, Pavel Mikhailik

INTRODUCTION Ferromanganese (FeMn) crusts from Mendeleev Ridge, Chukchi Borderland, and Alpha Ridge, in the Amerasia Basin, Arctic Ocean, are similar based on morphology and chemical composition. The crusts are characterized by two- to four-layered stratigraphy. The chemical composition of the Arctic crusts differs significantly from hydrogenetic crusts from the North Pacific Prime Zone (PCZ; Hein et al., 2013), such as a high mean Fe/Mn ratio (2.6 versus 1.3) and low Si/Al ratio (1.8 versus 4.0), with lower Mn, Ca, Ti, P, Ba, Co, Cu, Ni, Pb, Sr, and Zn and higher Si, Al, Mg, As, Li, V, Sc, and Th. Based on Arctic FeMn crust mineralogy, chemical composition, and growth rates, crust formation was dominated by three processes: Precipitation of Fe-Mn (oxyhydr)oxides from ambient ocean water, sorption of metals by the Fe and Mn phases, and fluctuating but large inputs of terrigenous debris (Konstantinova et al., 2017; Hein et al., 2017). The Mn and Fe phases are hydrogenous and reflect bottom ocean-water chemistry and the aluminosilicate phase contains stable detrital minerals such as quartz, feldspars, zircon, monazite, and clay minerals. A precise method of studying the distribution of elements in FeMn crust phases is sequential leaching that dissolves four mineral phases of different stability step-by-step, in the following order: easily leachable phase, mostly bio-calcite; manganese oxides; iron oxyhydroxides; and residual aluminosilicate minerals (Koschinsky and Halbach, 1995). Twelve bulk crusts and crust layer samples obtained from six hydrogenous FeMn crusts were studied. Those crusts were collected during Russian (Arktika 2012) and USA (HLY0805, HLY0905, and HLY1202) research cruises from different parts of the Amerasia Basin (Mendeleev and Alpha Ridges, Chukchi Borderland). Samples were chosen for the sequential leaching experiments based on their morphology, location, and water depth. Hydrogenetic crust (D07-33) from the Tuvalu EEZ, central-west Pacific Ocean, was included in the experiment for comparison. Recovery during the four-step sequential leaching, with respect to the bulk analyses, was between 80% and 120%.

Jan 1, 2018

By Delphine Pierre, Jean-Marie Augustin, Anne-Sophie Alix, Charline Guérin, Cecile Cathalot, Yves Fouquet, Arnaud Gaillot, Ewan Pelleter, Carla Scalabrin, Florian Besson

With the world’s growing demand for metals, seafloor massive sulfides (SMS) deposits are now seen as a possible mineral resource that could contributes to secure metal supply for human needs. SMS deposits are characterized by high concentrations of base metals and at some place high contents of precious and rare metals. Since 1977 and the discovery of the first high temperature (HT) hydrothermal vent and its sulfide mineralization and high biodiversity, more than 300 sites are known today. If the exploration strategy for detection of active hydrothermal sites is now robust, their associated mineralization will not (and must not) constitute a potential target for deep-sea mining due to environmental concerns and technical limitations. Recent studies on SMS deposits are rather focused on extinct and buried mineralized sites characterized by a lower biomass. Several geophysical techniques to explore and detect extinct SMS (eSMS) and buried SMS (bSMS) have been developed (e.g. Kawada and Kasaya, 2017; Szitkar et al., 2017, 2014) using different approaches (e.g. regional or local scale; ship-based or using underwater vehicles) with several degrees of success or limitation. Here we present results from acoustic surveys performed on the TAG hydrothermal district during the BICOSE (2014) and LEVE-SMF (2016) cruises and direct observation provided by HOV (Nautile) dives carried out during HERMINE cruise (2017). Acoustic data were acquired using two different multibeam echosounders (MBES): the hull-mounted Kongsberg EM122 (12 kHz, R/V L’Atalante) and the ROV-mounted RESON SeaBat 7125 (400 kHz, ROV Victor) (Figure 1). After processing, acoustic seafloor backscatter data from both MBES provides complementary qualitative results in relation to the seafloor composition. The analysis of the seafloor backscatter data obtained by near-seafloor surveys with the high-resolution 400 kHz MBES shows a clear relationship between low backscatter strength values and areas covered with pelagic and hydrothermal sediments whereas high backscatter strength values are associated to pillow lavas and basaltic scree. Intermediate backscatter strength values are rather related to old and younger eSMS as well as to mineralization on TAG active mound.

Jan 1, 2018

By Robert G. Ditchburn

The NW caldera hydrothermal vent field at Brothers volcano, of the Kermadec-Tonga arc, has associated massive sulfide mineralization. This includes an abundance of black smoker chimneys that contain significant concentrations of copper, lead, zinc and gold (de Ronde et al., 2005; de Ronde et al, 2010, under review). [ ] The oldest volcanic massive sulphide (VMS) samples recovered so far from Brothers have been dated using radiometric methods at GNS Science and found to be c. 1000 years old. By contrast, a volcanic cone that has formed in the southern part of the caldera has no associated VMS. Only elemental sulphur and Fe-oxide crusts are present here, samples of which have been analysed for their trace elements. From d34S values of sulfates and native sulfur, and the volume of gas (dominated by CO2 and H2S) discharging at the cone site, elements being deposited here are considered more directly magmatic in origin (de Ronde et al., 2005; 2010 under review). It has been discovered that deep-seated changes in volcanic activity at Brothers affect the NW caldera and cone site simultaneously, though the mineralogy at each site is so very different. Thus, the cone site is being studied to determine if elements being deposited there can be used as predictors of potential future VMS mineralisation as similar sites have been found at other volcanoes along the Kermadec arc and elsewhere. The frequency of these deep-seated magmatic events is considered important in the formation of Cu-Au-rich mineralization along arcs. The analysis of Fe within resulting hydrothermal plumes (surveyed by surface vessels), and trace elements in rock and mineral samples, are used to help determine the influence of magmatic contributions to the hydrothermal system. To verify that plumes are a reliable proxy for hydrothermal events depositing iron on the seafloor, Fe-oxide crusts from Brothers volcano cone have been dated to see if their emplacement coincides with highly Fe-enriched plumes in the water column. The radiometric dating techniques developed for barite-rich VMS, i.e. using 228Ra and 226Ra, were unsuitable for the Fe-oxide crusts because 210Pb was the only isotope detected by gamma spectrometry. Therefore, new techniques using 210Pb, 10Be and arsenic have been established.

Jan 1, 2010

By James R. Hein

A new data set of cobalt-rich ferromanganese (Fe-Mn) crust chemistry has been completed for the first detailed sampling of a latitudinal crossing of the Pacific equatorial zone of high biological productivity. Samples were collected in January-March, 1999, during the AVON 2 cruise aboard the R.V. Melville, Scripps Institute of Oceanography. Samples were collected from 4.6° N to 9.2° S latitudes along two ridges, the Marshall Islands-Gilbert Islands ridge (4.6° N to 3.5° S) and the Howland Island-Tokelau Islands ridge (1° N to 9.2° S). The two ridges are offset east-west in the region of overlapping latitudinal sampling by about 466 km. We determined the concentrations of 48 elements for 147 samples from 39 dredge hauls taken on 33 seamounts and island flanks that occur between the Marshall Islands to the northwest and Samoa to the southeast. Element concentrations can be examined as varying spatially and with water depth in the ocean and we examine those relationships based on statistical analysis of the chemical and spatial data. The mean Fe/Mn ratio of 1 and mean Co content of 4645 ppm are typical of West Pacific hydrogenetic crusts; but the mean Co content is low compared to those of some equatorial North Pacific sites, such as the Marshall Islands and Johnston Island EEZs. In contrast, the mean Cu concentration (1540 ppm) is 35% higher than the mean concentration for Pacific Ocean Fe-Mn crusts (998 ppm). Another striking difference is the 40% higher Ba concentrations (mean 3107 ppm) compared to typical Central and West Pacific crusts (mean 1876 ppm); but Ba concentrations are lower than those in California continental-margin Fe-Mn crusts (mean 4085 ppm). A final significant difference in Fe-Mn crust chemistry is Zr concentrations, mean 921 ppm (maximum 1523 ppm), which is about 30% higher in this data set compared to the previously determined mean value of 613 ppm for Central and West Pacific crusts. Zirconium has a strong positive correlation with Ba and a weak positive correlation with Mn.

Jan 1, 2003

By Francois P. Leroy

In the quest of studying the assigned blocks of seafloor for deep water mining, each member country of the ISA is thirsty for accurate information as to the level of resources available. Manganese nodules represent a large portion of the resources and are as precious as they are hard to locate and harvest. Resolving such challenges is what drives the technology development and yields instruments and products capable of serving this field of research. This presentation will study how manufactures of oceanographic instruments have pushed the technology envelop to in order to transform a collection of sensors and instruments into a seamless and adapted assembly working to serve the researcher and prospector in the challenging field they operate. Deep water data collection is characterized by the following challenges: ? Deployment, recovery and handling of the vehicle ? Producing high resolution at great distances ? Positioning that data with accuracy to relocate Teledyne Marine will present the work performed in its engineering laboratories to produce sub systems and systems now capable of delivering key information necessary to the proper cataloguing and exploitation of deep water mineral mining. Understanding and controlling the alternative resources available to each country will allow better management of current traditional land based minerals.

Jan 1, 2010

By Kiseong Hyeong

The Intertropical Convergence Zone (ITCZ), where the southeast and northeast trade winds converge, is the effective climatological barrier that separates the southern and northern hemispheres in terms of dust budget. Asian and N. American dusts dominate in the Pacific north of the ITCZ, while Central and S. American dust prevails south of the ITCZ. In order to understand the nature of latitudinal and depth-related variations of mineral composition in terms of position relative to the ITCZ, deep-sea core sediments were collected from 9°N to 17°N at a 2° intervals along the 131.5°W meridian and analyzed for mineral composition. The amount of illite in surface sediments decreases gradually from 65% at 17°N to 31% at 9°N. In contrast, smectite increases from 11% to 56% southward. The observed mineralogical variation toward the ITCZ is attributed to the increased supply of volcaniclastic material transported via the southeast trade winds from the Central and South America source regions. Smectite-illite transition, a phenomenon that the amount of smectite increases over illite, occurs at around 10°N, the northern margin of the ITCZ. This result indicates that the change in latitudinal position of the ITCZ in the geological past could be recorded by the smectite-illite transition in deep-sea cores. The cores studied show down-core variation of mineral composition from illite-rich at the surface to a smectite-rich clay suit at depths, similar to the latitudinal variation. The smectite-illite transitions observed in these cores are likely the records of changes in latitudinal position of the ITCZ. The depth and age of the smectite-illite transition is getting shallower and younger towards the equator, implying that the ITCZ was located farther north during late Tertiary and has shifted southward to the present position of 5°N~10°N.

Jan 1, 2004

By Robert M. Owen

Recent advances in coring technology and in the development of shipboard and/or in situ geochemical geochemical analysis systems have greatly improved our ability to collect and analyze exploration samples, particularly for marine placer exploration programs. The potential benefit of these improvements cannot be fully realized, however, until we also develop more efficient methods of data reduction and interpretation. Specifically, there is a need to provide prospectors with rapid and useful interpretations of the raw geochemical data so that they can exploit promising results and otherwise optimize the exploration program while the exploration vessel is still at sea. The goal of this project has been to identify and/or develop computer software which is capable of making the necessary data reduction calculations and which can be run on conventional desk-top computers. All work on this project has been supported through a research grant from MMTC-CSD to The University of Michigan. The first stage of this effort involved an evaluation of commercially available (i.e., "off the shelf") software to determine its suitability for use in marine placer exploration applications. Various commercial software packages, each purportedly capable of making different types of statistical and/or mathematical calculations, were tested by evaluating their performance in handling geochemical data sets representative of actual marine placer locations. These data sets include the positions and results of chemical analyses of suites of sediment samples collected from areas of known or suspected marine placers along the Bering Sea coast of Alaska. The evaluation of each commercial program involved a comparison between the results obtained from using the test program

Jan 1, 1991

By Kyung-Ho Park

The smelting leaching process is known as one of the most favorite methods for the processing of deep-sea manganese nodules because of its smaller environmental impact and easiness of manganese recovery. The sulphuric acid pressure leaching of the matte prepared from deep-sea manganese nodules was studied to dissolve the valuable metals. Almost complete dissolution of Cu, Ni, and Co from matte was achieved under the following conditions: leaching temperature 180°C, time 4 hours, PO2 10 kgs/cm2, acid concentration 2.5% (vol/vol), pulp density 5%, ammonium sulphate 40 g/l. Under these conditions the iron concentration of leach liquor was 0.95 g/l. Optimization of leaching parameters was carried out by statistical design of experiments using 23 full factorial matrix. The linear and interaction co-efficients were evaluated for dissolution of metal values and also for iron concentration in leach liquors.

Jan 1, 2003

By Ian B. Clark

In October-November 1993, the Centre for Cold Ocean Resources Engineering, Memorial University of Newfoundland and University of Victoria jointly carried out reconnaissance surveys at Pine Cove, Baie Verte, Newfoundland. Pine Cove is the site of a multi-year study examining the environmental impact of a shallow water small-scale marine placer gold mining operation. The reconnaissance survey data collected will be used to develop a multi-year environmental effects monitoring (EEM) program for Pine Cove, Baie Verte, but more generally an EEM protocol for shallow water small-scale marine placer mining, which meets the requirements of Canadian government regula¬tors such as Environment Canada and the Department of Fisheries and Oceans. The Pine Cove mining operation is currently scheduled for the summer of 1995, and will use two mining methods: a hydraulic suction dredge in shallow water (<10 meters) operated by a scuba diver, and a hydraulically actuated clamshell dredge in deeper water (-30 m). A centrifugal concentrator will be used to extract the heavy minerals from the mined marine sediments, and the tailings will be returned to the sea floor via a suspended discharge pipe. The reconnaissance work at Pine Cove included geophysical, geochemical, oceanographic and biologi¬cal surveys, providing data which will enable prediction of the potential environmental impacts of the proposed mining operation. The geophysical surveys showed the sea floor to be covered by varying

Jan 1, 1994

By Eric J. Foell

The Offshore Technology Conference (OTC) was founded in 1969 when a group of scientific and technical societies organized an annual conference and exhibition dedicated to technologies used in the offshore oil, gas and mining industries. Currently, OTC is sponsored by 12 industry organizations and societies. These include: American Association of Petroleum Geologists (AAPG); American Institute of Chemical Engineers (AIChE); American Institute of Mining, Metallurgical, and Petroleum Engineers (AIME); American Society of Civil Engineers (ASCE); ASME International Petroleum Technology Institute; Institute of Electrical and Electronics Engineers/Oceanic Society (IEEE-OES); Marine Technology Society (MTS); Society of Exploration Geophysicists (SEG); Society for Mining, Metallurgy, and Exploration (SME); Society of Naval Architects and Marine Engineers (SNAME); Society of Petroleum Engineers (SPE); and The Minerals, Metals, and Materials Society (TMS). OTC also has two endorsing organizations, the International Association of Drilling Contractors (IADC) and the Petroleum Equipment Suppliers Association (PESA), as well as 6 supporting organizations that include the American Petroleum Institute (API), the Independent Petroleum Association of America (IPAA), the Institute of Marine Engineering, Science, and Technology (IMEST), the International Association of Geophysical Contractors (IAGC), the National Ocean Industries Association (NOIA), and the United Kingdom Offshore Operators Association (UKOOA). From its earliest years, the OTC has been held during the first week of May in Houston, TX, initially at the Albert Thomas Convention Center where OTC?69 drew 4200 attendees and 200 exhibitors. As the conference grew and became established as the world?s foremost event for the development of offshore resources in the fields of drilling, exploration, production, and environmental protection, the venue was changed to the Astrodomain Complex, with technical paper sessions and most exhibits taking place in the Astro Hall. The numbers of attendees and exhibitors varied somewhat over the years, primarily in accordance with the fortunes of the international oil and gas industry. At its height in the early 1980s, OTC registered attendance exceeded 100,000 with more than 2500 exhibitors forcing expansion into the Astro Arena and even the Astrodome.

Jan 1, 2005

By Henk van Muijen, Jan Willem de Wit

1.1 Profile IHC Holland Merwede IHC Holland Merwede is world market leader in the construction of specialist dredging equipment and large-size custom-built offshore vessels. The clients of IHC Holland Merwede include major dredging companies, oil and gas exploration groups, offshore contractors and government authorities. IHC Holland Merwede is focused on the continuous development and innovation of technology to ensure maximum performance and efficiency of its designs and constructions supplied to the dredging and offshore industries. IHC Holland Merwede has a staff of approximately 2,000 at its locations in Hardinxveld- Giessendam, Kinderdijk, Krimpen aan den IJssel, Sliedrecht, Delfgauw, Goes, Hendrik Ido Ambacht and Heusden. Besides worldwide representations, IHC Holland Merwede has branches in China, Houston (USA), India, the Middle East and Singapore. 1.2 Mission IHC Holland Merwede’s mission is to optimize value by anticipating and satisfying its client’s requirements, with efficient advanced technology solutions. The group’s aim is to be consistently at the forefront of technology development, in the business sectors in which it operates.

By J. Robert Woolsey

The Marine Minerals Technology Center (MMTC) was established by Congress in FY 1988 as part of the Mineral Institutes Program, administered by the U.S. Bureau of Mines under the auspices of the Department of the Interior. The primary objective of the MMTC is to encourage the development of selected mineral materials from U.S. seabeds by providing opportunities for appropriate engineering systems research, development, and technology transfer within academic, government, and industrial communities. The center will also provide the leadership and facilities required for the education and training of the nation&apos;s scientists and engineers in the field of ocean mineral development. Because of the broad spectrum of study encompassed by the field of ocean mining and mineral resources, the MMTC is organized to include separate divisions for nearshore and deep ocean research. The Continental Shelf Division is administered by The Mississippi Mineral Resources Institute (MMRI) of the School of Engineering at The university of Mississippi. Operational activities will be based at the John C. Stennis Space Center near Bay St. Louis, Mississippi and the Gulf Coast Research Laboratory, Ocean Springs,

Jan 1, 1988

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 Russell Parrott

Acoustic techniques offer a rapid, economical, non-intrusive method of obtaining information about the stratigraphy and properties of seafloor sediments. During the past decade there has been a dramatic increase in the level of sophistication of high resolution seismic reflection equipment used for seabed and subsurface studies and in the signal processing techniques applied to the data collected with these systems. Processing of data from acoustic sources with repeatable and calibrated output, allows quantitative measures of the reflection coefficient, acoustic attenuation and scattering parameters of the sediments on the seafloor. Graphic recordings of seismic reflection data emphasize the coherent portion of the reflected energy for qualitative estimate of sediment properties and subsurface stratigraphy. Through application of signal processing techniques, quantitative information can be extracted from the coherent and incoherent components of seismic reflection data for estimation of surface character and sediment properties. These calculated parameters can be applied through interpolation between areas of available groundtruth. Acoustic techniques are used extensively to establish the regional geological framework of project areas and can also be used to extrapolate available groundtruth data into previously unsampled areas, and to optimize the design of a sampling program to provide the necessary groundtruth for the survey area.

Jan 1, 1985

By Akira Usui

Occurrence of hydrogenetic ferromanganese crusts has been well documented over inactive seamounts in the central and southern Pacific Ocean. It has been thus believed that the hydrogenetic crusts develop preferentially at water depths between about 800 to 2500 meters. In fact, according to the Manganese Crust Database (F. Manheim, 1988), only two occurrences are known at water depths below 5000 m out of 819 occurrences cited in the database. Unexpectedly, we found typical hydrogenetic ferromanganese crusts from deep-sea floors; 1) outcropping old volcanic basement over the Philippine Sea Plate (abandoned spreading centers and subducting old oceanic crusts) and 2) one from the slope of an abyssal hill in the Central Pacific Basin (Cretaceous deep-sea basin) at water depths ranging between 5200 to 6100 meters. We report their occurrences with submersible observations from Shinkai 6K, physical parameters (such as thickness of crusts about 2-4 cm in maximum), chemical composition, petrology of substrate, and results of Be-10 dating for some samples in comparison with typical Co-rich manganese crusts from the Central Pacific seamounts. The preliminary chemical and mineralogical analyses reveal that they are of typical hydrogenetic origin, and typical of iron-manganese oxide mineral, vernadite, slow and probably continuous growth, and lower content of Co than the Central Pacific seamount crusts. The occurrences and nature of the crusts indicate that deep-sea floors are also optimal for the growth of hydrogenetic crust even at 5000 m water depth or deeper, only if oxygenated deep waters are supplied and the sea-floor morphology keeps stable enough for significant geological time period. Additional details of chemical analyses will be prepared by November and to be shown in the conference.

Jan 1, 2001

By Mark D. Hannington

Drilling of the active Trans-Atlantic Geotraverse (TAG) deposit during ODP Leg 158 indicated that the size of the mound-stockwork complex is approximately 3.9 million tonnes, including 2.7 million tonnes of massive and semi-massive sulfide (ca. 2% Cu) at the seafloor and 1.2 million tonnes of mineralized breccias (ca. 1% Cu) in a subseafloor stockwork. Quartz-pyrite veining in the stockwork zone extends from about 40 meters below seafloor (mbsf) to a depth of 95 mbsf. Siliceous wallrock breccias in the lower part of the stockwork grade abruptly into chloritized basalt breccias at the margins of the mineralized zone, and massive sulfides at the flanks of the deposit onlap relatively unaltered, partially hematized basalts. The pipe-like dimensions of the stockwork zone do not exceed the diameter of the sulfide mound. Comparisons with samples collected during earlier dive series confirm that the vent complexes at the surface of the mound are not representative of the bulk composition of the deposit. Dramatic vertical zonation of metals within the mound suggests that a long history of hydrothermal reworking has effectively stripped the constituents that are soluble at lower temperatures from the massive sulfides and concentrated them at the top of the deposit through a process of zone refining.

Jan 1, 1998

By Ning Yang, Sup Hong

INTRODUCTION Metal components contained in deep-seabed mineral resources are being highlighted as “energy metals”, which are widely utilized in the entire fields of energy: harvesting and generation, storage and transportation, and saving. Those are mostly trace and rare metals, and rare earth elements as well: manganese, nickel, cobalt, copper, molybdenum, tellurium, selenium, platinum, etc. Toward low carbon society, for global sustainability, the role of metals and minerals is growing up in industries of energy and transportation [1]. In this context, the production and supply of energy metals from deep seafloor have to be approached also based on sustainable development. In deep-seabed mining activity, the sustainability is focused on potential impacts on ecosystems in benthic area and water column. The environmental impacts in deep-seabed mining are caused basically by intervention in benthic zones and transportation of materials. Those are, in particular, removal of benthic habitats, generation and dispersion of sediment plumes, surface transportation of seawater and sediment, tailing from mining vessel, sound and light noises, and chemical leakage, etc. This paper is aiming at fundamental guidance towards sustainable mining of polymetallic nodules.

Jan 1, 2018

By V. Alexandrov

This paper presents the results of theoretical investigations of the energy requirements of the hydraulic lifting of mined materials from the seabed to the sea surface in the deep-sea mining of solid minerals such as manganese nodules in the Clarion-Clipperton region of the Pacific, situated on the sea floor in water depths of 4,500 m or more. The principal element of the developed underwater transport system is the Underwater Chamber, which is connected by flexible pipeline to a mining machine that gathers nodules from the seabed, mixes them with seawater, and feeds them into a flexible pipeline. In this paper, we discuss the question of the optimum water depth for placement of the Chamber, the interior of which is designed to maintain a 1-atmosphere pressure. We present a method for calculating this depth as it relates to the mechanical characteristics of solid particles, the shapes and size distributions of the particles, particle and slurry density, and other properties. These investigations were carried out in hydro-transport laboratory of the Saint-Petersburg Mining Institute and the hydraulic laboratory of Faculty Environmental Engineering in Wroclaw Agricultural University. KEY WORDS: deposit, nodule, flexible pipeline, pressure drop, concentration, hydromixture

Jan 1, 2005