Search Documents

By Jeremy Spearman, Mark Lee, Jon Taylor, Neil Crossouard, Bramley Murton

"SUMMARYThis paper describes challenges faced when executing a programme of monitoring to measure the dynamics of currents and sediment plumes at a seamount and the solutions identified to deliver the measurements. The study site was the Tropic Seamount, which extends some 3300m above the surrounding seabed and is found at the southern limit of the Canary Island Seamount Province. The purpose of the study, which forms part of the Marine E-tech project, was to provide information on the interaction of flows with the seamount and to assess the behaviour of sediment plumes that could be generated from potential seabed mining operations targeting the recovery of ferromanganese crusts. Since the crest of the seamount is submerged to a depth of 1000m, much of the work was undertaken using remotely operated and autonomous vehicles supported by measurements from the surface vessel. Despite only limited information on currents being available for planning purposes, the combination of short term forecasting using a 3-dimesional hydrodynamic model of the study area coupled with the collection and analysis of reconnaissance data collected during the first phase of measurement activities made it possible to plan and execute a number of detailed hydrodynamic experiments on the seamount crest. The results of these experiments have advanced the understanding of the behaviour of sediment plumes in the deep ocean and will ultimately improve our ability to manage the impacts which may arise from deep sea mining operations."

Jan 1, 2017

By Andrea Koschinsky, Sophie Paul

"INTRODUCTIONOnce again deep-sea mining has been receiving a lot of attention in recent years. Industrial and political advancements also call for environmental baseline studies and analyses to aid the development of standards and monitoring protocols. As part of the EU research project “JPI Oceans: Ecological Aspects of Deep-Sea Mining”, the RV Sonne cruise SO242 to the Peru Basin revisited the DISCOL area that had been artificially disturbed in 1989. This offered the unique opportunity to study a deep-sea site 26 years after a disturbance similar to manganese nodule mining had been carried out (Figure 1). A comparison of a variety of undisturbed and disturbed sites shed light on the re-establishment of a geochemical equilibrium and a range of baseline values. This information can help to inform standard development for monitoring and mining purposes.Heavy metal data and its applicationResearch findingsDuring the cruise, disturbed and undisturbed surface sediment was sampled. The pore water analyses show that the 26 years old disturbance is not visible in the metal profiles and that the pore water reaches equilibrium through diffusive fluxes relatively quickly. The sediment, however, shows some differences between disturbed and undisturbed sites in the upper 20 cm, even after 26 years. Lower concentrations in the usually manganese-oxide rich top layer, variations and “unnatural” peaks in the manganese profiles, for example, suggest removal or mixing of the top layer (Figure 2)."

Jan 1, 2017

By Matthew Kowalczyk, Steve Bloomer, Peter Kowalczyk

"Mineral deposits found near seafloor hydrothermal venting are of great economic interest. Valuable metals such as gold, copper, zinc, and other polymetallic sulfides are found in appreciable grades in seafloor massive sulfide (SMS) deposits associated with these vents. For mapping these deposits, electromagnetic prospecting is one geophysical method that is very useful because copper/gold rich deposits are highly conductive.Ocean Floor Geophysics (OFG) in 2008 developed the first EM system to successfully map the limits of conductive mineralization in a survey at the Solwara 1 deposit (Kowalczyk, 2008). Since then, towed coincident loop time domain systems have been developed by Waseda University (Nakayama and Saito, 2016) and have successfully detected known mineralization buried at 30m depth. Using a deep tow controlled source electromagnetic (CSEM) array, very clear anomalies have been measured (Murton, 2017) over known mineralization at the TAG field on the mid-Atlantic ridge.In 2014 and 2015, OFG partnered with Fukada Salvage and Marine Co. Ltd. and the Scripps Institution of Oceanography to map methane hydrate deposits off the coast of Japan using a towed controlled source electromagnetic (CSEM) system developed by Scripps. These hydrate deposits are resistive targets, and the Scripps system successfully mapped subsurface electrical resistivity distributions to depths of several 100 metres below the seafloor. OFG is attempting to extend the Scripps CSEM technology to map subsurface conductive SMS deposits to a similar range of depths below the seafloor."

Jan 1, 2017

By J. W. Jamieson

INTRODUCTION Hydrothermal vents that form seafloor massive sulfide (SMS) deposits represent unique biodiversity hotspots that host many species that are found only at these sites. The destruction of these habitats remains one of the greatest environmental risks associated with proposed mining of SMS deposits. For this reason, there is a growing movement to protect active vent sites from direct and indirect effects of seafloor mining (Van Dover et al., 2018). Mitigating the adverse effects of mining on these ecosystems may prove to be one of the greatest challenges facing the marine minerals industry. At the same time, there is increasing evidence that inactive or extinct hydrothermal systems, which do not host the density or diversity of animals typical of active vents, may constitute a significant proportion of the SMS resource potential on the seafloor. Mining inactive SMS deposits may therefore present an extractive opportunity that does not necessitate the disturbance or destruction of active vent habitats. However, if mining of SMS deposits is to take place only at inactive vent sites in order to protect active vent ecosystems, a clear definition of what defines a site as active or inactive is necessary. ACTIVE AND INACTIVE SEAFLOOR MASSIVE SULFIDE DEPOSITS Our understanding of the number of inactive deposits, their size and grades, and how they are preserved on the seafloor remains limited, largely due to the challenges associated with finding these deposits. Over 90% of all hydrothermal vent fields discovered so far are hydrothermally-active. Almost all of these sites were discovered through the detection of chemical anomalies associated with active hydrothermal venting via water column surveys. Inactive sites have no associated hydrothermal plume, and thus the well- established plume survey exploration method is not effective. As a result, very few truly inactive sites inactive sites have been discovered. Alternative exploration methods, such as spontaneous potential (SP) surveys, magnetic surveys, and high-resolution mapping are required (Cherkashev et al., 2013; Jamieson et al., 2014; Tivey and Johnson, 2002). As methods for locating inactive deposits continue to develop, our understanding of the distribution and resource potential of these deposits will increase, and the focus of resource exploration will shift from active to inactive vent sites. However, for now, most exploration and deposit development activities remain focused on active vent fields.

Jan 1, 2018

By Raymond A. Binns

Exploration for high-value massive sulfide deposits on the ocean floor typically commences with a search for chimney fields in appropriate geological settings, followed by collection and assaying of standing chimneys. Individual chimney fields are generally too small in aggregate volume to constitute viable resources in their own right. Unless numerous small fields occur in reasonably close proximity, presence of plentiful sub-seafloor mineralization with acceptable metal tenor is the more likely requirement for potential exploitation. Expensive drilling is required to prove up mounds of collapsed chimneys, or dilatory sheets and veins or replacements of massive/semimassive sulfide (?stockworks? or ?manto?-like bodies) in underlying host rock. Where multiple targets have been defined, as many parameters as possible are desirable to help rank them for drilling.

Jan 1, 2011

By Peter A. Rona

The Mid-Atlantic Ridge in the central North Atlantic and the Gorda Ridge within the U.S. Exclusive Economic Zone off northern California and southern Oregon are yielding new discoveries of seafloor hydrothermal mineralization. The TAG hydrothermal field in the rift valley of the Mid-Atlantic Ridge near 26 degree N, 45 degree W has been a site of international collaborative research since the discovery there of extensive manganese deposits associated with low temperature hydrothermal activity in 1973 as part of the TAG (Trans-Atlantic Geotraverse Project). The first high-temperature hydrothermal activity, massive sulfide deposits and vent biota discovered in the Atlantic were found at the TAG hydrothermal field in 1985. Collaborative dive series with DSV ALVIN in 1990 and in 1991 with the two Russian MIR submersibles in the TAG field have found and sampled large inactive sulfide mounds in addition to the previously known active sulfide mound. The active sulfide mound on the floor of the rift valley is about 250 m in diameter and 40 m high with a concentric zonation of mineral types and flow regimes decreasing in temperature from 365 degree C black smokers at the center to white smokers and diffuse flow toward the margins. The recent dive series in coordination deep-towed instrument surveys have delineated a zone extending about 5 km along the lower east wall of the rift valley of inactive sulfide mounds up to a kilometer in diameter. MIR Mound in this zone consists of a central sulfide zone about 400 m in diameter and 50 m high surrounded by a halo of low-temperature deposits to 200 m wide. Inactive sulfide chimneys contain the first primary, free gold grains found at a hydrothermal site on a mid-ocean ridge (P.A. Rona, Y.A. Bogdanov, E.G. Gurvich, N.A. Rimski-Korsakov, A.M. Sagalevitch and M. D. Hannington, 199 1 EOS, Transactions, American Geophysical Union, 72:470-471 and Journal of Geophysical Research, submitted).

Jan 1, 1992

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 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 James R. Hein

Rodriguez Seamount, located 150 km off the central California coast at the base of the continental slope, was studied using the ROV Tiburon aboard MBARI?s R/V Western Flyer, October 13-16, 2003. Fe-Mn crust and rock samples were collected along the SW flank of the seamount at water depths from 700 to 2100 m; bottom-water dissolved oxygen content (O2) and temperature were determined at each sample site. Fifty-three samples of bulk crusts, crust layers, and surface scrapes (~0.5 mm) were analyzed for 59 elements. Data allow for the correlation of crust compositions with precisely known water depths and seawater O2 measured at the actual site of sample collection. This is the first detailed study of Fe-Mn crust compositions in a region of strong continental-margin upwelling. Compared to open-ocean seamount Fe-Mn crusts, Rodriguez crusts have significantly higher (2-6 fold) mean concentrations of Fe (26.9%), Al (1.65%), Si (13.0%), Cr (82 ppm), Th (64 ppm), and Ag (1.7 ppm); and significantly lower (2-8 fold) mean concentrations of Ca, P, Bi, Co, Cu, Ni, Tl, and especially Te (8.2 times lower). All but one Fe/Mn ratio are >1 compared to <1 ratios for open-ocean crusts. O2 contents (0.35-2.03 ml/L) are nearly perfectly corrected with water depth and elements correlated with one are correlated with the other. The Fe-Mn surface scrapes represent 60-450 ka (mean 150 ka) of growth, whereas the dissolved oxygen contents of seawater represent an instant in time. Assuming that the entire sample set was affected uniformly by oceanographic changes, we suggest that correlation of elements with O2 may reflect oceanographic processes. O2 has a negative correlation with P, V, As, Fe, U, Be, Pb, Cr, Mg, Y, Bi, Te, and REEs (except Ce) and a positive correlation with aluminosilicate-hosted elements (Al, K, Rb, Cs). This later relationship is related solely to water depth, indicating that detritus shed down the seamount slopes accumulates in greater abundances in deeper-water crusts. Si/Al ratios indicate that the detritus includes a large component of biosilica produced by upwelling-mediated high productivity. These observations are supported by positive correlations of aluminosilicate-hosted elements with crust growth rates (range 1.2-13.0 mm/Myr). In contrast, other elements (Sr, Co, Mn, Mg, Te, As, Mo, V, W, U, Ti, Ni, REEs, etc.) are negatively correlated with growth rates. Growth rate has a weak positive correlation with O2. These compositional characteristics indicate that even though low-O2 seawater acts as a reservoir for Mn and associated elements and produces slow growth rates, which would allow for the concentration of elements and surface oxidation processes to occur, the high rate of input of detritus and high bioproductivity ameliorate the strong concentration of most metals. This dilution is significantly enhanced by the doubling of FeOOH in the crusts--the main cause of the generally high growth rates compared to open-ocean crusts. The high growth rates limit the oxidation of Co, Tl, and especially Te on the crust surface, which is reflected by their relatively low concentrations. Within the range of oxygen contents measured, O2 has less of an influence on crust chemistry than does the availability and incorporation of FeOOH and detritus.

Jan 1, 2004

By S. C. W. de Jong, E. de Hoog, J. M. van Wijk, S. J. Dasselaar

Introduction Technology development for sustainable, safe, reliable and efficient mining of polymetallic nodules in the deep seas requires careful design, thorough understanding and integrated testing of all equipment, physical processes and (sub) systems involved (Dasselaar et al [1]). Proceeding from Vertical Transport System (VTS) experiments at IHC laboratory scale by Van Wijk [2], with typical system dimensions of several meters, to prototype or pilot scale testing with typical dimensions of several kilometers, is a giant leap. Naturally, intermediate steps are required in order to mitigate the possible risks in the full-scale system’s (physical) processes. Within the EU program Blue Mining (2014-2018), possibilities emerged for performing experiments at intermediate scale: the so-called medium-scale vertical slurry experiments. Near Freiberg, Germany, the village Halsbrücke possesses a 140 meter deep empty vertical mine shaft, perfectly suited for housing the test setup. For this purpose, a 318 meter long 145 mm pipeline circuit was constructed, including both a 130 meter high vertical riser and fall pipe section. A purpose-built sediment injection and separation system was deployed, including a 55 kW centrifugal pump. The riser section has been equipped with sensors capturing pressure, temperature, flow velocity, volumetric concentration and flow visualization. The planning, modification and construction of the test facility site itself is described by Müller et al [3]. The present paper describes the objectives, experimental program, equipment, and the preliminary results. Publications on in-depth results are foreseen in the (near) future.

Jan 1, 2018

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 Stephan K. Schwank

In mid 1993, Bauer Spezialtiefbau GmbH, based in Germany got the order to develop a sampling tool capable of penetrating all different types of seabed sediments including cobbles and boulders and into bedrock. BHP and their partners Benguela Concessions Ltd., had been convinced by the Bauer Trench Cutter Technology and a large scale test in Germany that this system will be the right one to fulfill their expectations for sampling the diamond area off the coast of Namibia. The technique of the tool is based on Bauer&apos;s standard cutter technology, which is widely used for the installation of cut-off and diaphragm walls all around the world. The two counterrotating cutter wheels with 12.1 tom torque each cut an area of 3 x 1.2 m (up to 3 x 3 m are possible). The material mixed with seawater was then pumped to the separation plant on board the vessel Geomaster with a capacity of approximately 700 m3/h. Cutter wheels and mud pump were mounted on a special cutter frame and connected by wire ropes and hydraulic hoses to the vessel. An outer frame with four telescopic legs supported the cutter vertically on the uneven seabed and allowed a controlled penetration of the tool up to 6 m into the diamond bearing ground. The tool required a total power installed of approximately 800 kW. All hoses, the 6-inch mud hoses as well as the hydraulic hoses, were stored and compensated on drums on board suitable for a water depth of up to 200 m. Launch and recovery of the tool was effected through the moon pool of the vessel and the 25 m high, special designed drill tower. The 65? to sampling tool had been commissioned in early 1994 in Cape Town. After intensive testing the sampling programme of more than 4000 holes could be successfully completed by January 1995.

Jan 1, 1998

By Pia-Maria Haselberger, Marc Schiemann, Christian Frühling, Nicolas Richter, Hendrik Wehner, Andreas Kaschube

"The paper provides the principle considerations for a novel vehicle class within the scope of the project Large Modifiable Underwater Mothership (MUM). The main idea for these ships is to create a highly modular building block system for the global layout. This building block system allows for a mission-dependent module assembly. For the purpose of deep sea mining for example, the range of tasks reaches from multipurpose transportation and exploration missions to supporting tasks in up to 5000 m depth, e.g. energy supply. Topics covered in this paper are related to potential missions for these vehicles, the modular layout and the structural layout of a separate block module. The paper closes with a conceptual design example for this class.Index Terms—MUM, UUV, underwater mother ship, autonomous underwater vehicle, modular, deep sea, conceptual designI. INTRODUCTIONAs one of the leading economic nations, Germany is in need of energy and raw materials. In the 21st century, marine resources are a prominent and promising alternative to land based resources. However, there are challenges that need to be considered. Rough and often poorly plannable weather conditions prevail distant to the marginal seas. Ice coverage makes offshore services inefficient and costly in Polar Regions. The average ocean depth of 3500m and the associated environment conditions cause difficulties in fulfilling tasks in the deep sea. The project Large Modifiable Underwater Mothership (MUM) [1] will enable more efficient solutions in order to accomplish undersea duties and services in harsh conditions.This joint project comprises workshares from Atlas Elektronik, EvoLogics, thyssenkrupp Marine Systems, the University of Rostock and the Technische Universität Berlin. The principle idea of the project is the conception of a novel vehicle class. With highly modular autonomous underwater vehicles, this class will be capable of undertaking a variety of different tasks. Classically engineered vehicle structures will be split into single basis modules which can be flexibly assembled with specialized mission modules to form potent systems for individual assignments. The group of basis modules consists of units for navigation, vehicle control, propulsion and energy generation via fuel cell technology. The potential reusability of system relevant modules leads to a significant cost reduction and to shortened development periods compared with conventional vehicle concepts. The integration of newly designed additional mission modules is possible with little effort and a separate commercialization of single modules is feasible."

Jan 1, 2017

By R. C. Newell

The primary objective of this study was to establish the fate and distribution of material rejected during marine aggregate dredging, and the extent to which this is associated with spatial changes in biological community composition. Two actively dredged sites in the southern North Sea (Licence Areas 430 and 106) were selected in order to provide a comparison of impacts between sites subjected to different levels of dredging intensity and of contrasting environmental conditions. Dispersal of material rejected during the dredging process was monitored by means of acoustic doppler current profiling techniques (ADCP). Composition of the substratum and benthic invertebrate assemblages were investigated by the analysis of seabed grab samples. It was found that dredging in both areas had an impact on seabed bathymetry in the form of dredge furrows and also led to a reduction of the coarse gravel-sized components of the worked area. Sand sized particles were shown to increase in the surface deposits of both dredged areas. This is likely to reflect both the removal of coarse particles as cargo and the settlement of finer particles rejected during overboard screening. Dispersion and settlement profiles of material rejected by dredging vessels suggested that the majority of the suspended sediment load resulting from overboard screening settles to the seabed within 500 m. Some evidence of suspended sediment loads above background levels were noted at distances of up to 2 km from the working vessel. Analysis of the particle size composition of the deposits, along the axis of transport of material from the dredged sites, suggested that the impact on the sediment composition outside the boundaries of the dredged sites is dependent on the strength and direction of net sediment flux at the seabed. Benthic invertebrate communities within the dredged zones of both areas were found to differ significantly from communities in nearby undredged deposits. A major suppression of species richness and abundance was noted in the dredged sectors of both sites when compared to control locations. A ?footprint? of potential impact on the benthic fauna was noted in samples taken along the axis of sediment transport at distances of up to 1750m outside the boundaries of Area 430. In contrast, impacts on benthic community structure at Area 106 appeared to be confined to the immediate vicinity of the dredged zone itself. This apparent difference in impacts, beyond the boundaries of the dredged sectors between the two study sites, was thought to be a reflection of the smaller quantities of material rejected at Area 106 and the weak seabed sediment flux which is characteristic of this area. These findings, along with those of numerous dredging impacts studies, were then used to make generalised predictions of macrobenthic community recovery following marine aggregate extraction in a variety of seabed habitats.

Jan 1, 2004

By Julian Malnic

Various natural, commercial, engineering and operational factors govern the evolution of approaches taken in the exploration for Seafloor Massive Sulphides (SMS) and in delineating the resource. These stages are prerequisites to the proposed mining of SMS deposits. This paper presents and analyses these factors from the view of an SMS exploration company that is pioneering the exploration of this rich alternative source of zinc, copper and gold. Current exploration practices developed by Marine Scientific Research (MSR) workers for SMS deposits are expected to give way to industry-generated methods as the SMS exploration industry gathers momentum. The exploration process falls into three phases that are described below: Prospecting (locating targets), Indicating Resources, and Measuring Mineral Resources Considerable streamlining of the SMS exploration process will accelerate the rate of discovery. The economics of SMS mining are projected to be superior to comparable terrestrial mining operations in both operating cash cost and capital terms.

Jan 1, 2001

By John Halkyard

Deep ocean mining is experiencing a rebirth following many years of low levels of activity. Large scale mining is being projected as just over the horizon. A lot has been made of the advances in deep water oil and gas developments over the last thirty years, and how this technology is directly applicable to ocean mining. The authors present their views on this from a perspective of a legacy of participating in the development of manganese nodule mining systems in the 1970s, followed by thirty years in the deepwater oil & gas arena. While it is true that great advances have been made in subsea technology, the differences between mining and oil and gas recovery should not be diminished. Fundamentally, oil and gas are stored in compact reservoirs under pressure. Any intervention leads to flow of the material up a pipe to the surface. The seabed hard minerals are stuck in place, either adhering to sticky pelagic sediment (nodules) or bonded together as hard rock (massive sulfides). The minerals require complex machinery in order to be extracted, sized, concentrated and lifted to the surface. Once at the surface the ore must be dewatered, de-fined and transferred to shore for processing. The overflow from this dewatered product must return to the sea in an environmentally satisfactory manner. These steps involve technology unique to mining that has to be addressed in a methodical fashion before commercial mining systems can be designed. The presentation will discuss the critical technical challenges of deepsea mining and thoughts on different routes to commercialization. The program will address the critical technical challenges, as perceived by the authors, and steps required to address them. Alternate development programs will be discussed focusing on nodules and sulfide. Keywords: manganese nodules, polymetallic sulfides, ocean mining

Jan 1, 2011

By NA UMC

Abstract Booklet

Dec 1, 2022

By John Parianos, Simon Richards

SUMMARY The Clarion Clipperton Zone (CCZ) hosts the most valuable deposit of polymetallic nodules yet discovered. Understanding the geology of this deposit is key to its effective exploration and mining. Nautilus Minerals (via its subsidiary Tonga Offshore Mining Limited; TOML) has been progressing its understanding of the relationship between seafloor morphology/structure and nodule abundance/morphology, both locally (within its contract areas), and globally (across the CCZ and the span of its contract areas of almost 70% of the CCZ). We present the first results of a project with the aim of developing a method to quickly and accurately map seafloor morphology/structure (Tectonic Subcomponent scale) without the necessity for high resolution seafloor multibeam data. Furthermore, the results presented here will allow a first attempt in understanding the relationship between seafloor geomorphologically-defined zones and plate-scale tectonics of the CCZ and adjacent plate segments. INTRODUCTION A relationship between the type of geochemical active layer and nodule abundance/morphology has long been understood (ISA, 2010). Consideration of the range of differing nodule types found within, but especially between, the TOML contract areas allowed Parianos and Pomee (2017) to refine this relationship further via interpreted thickness and dynamism of the geochemically active layer. The scale of the deposit, both in terms of space and time is staggering (a 10-20 cm thick deposit, spanning almost 4500 km, varying within a circa 10 Ma period), but a segment wide geological map may one day prove to reflect controls on nodule formation and distribution.

Jan 1, 2018

By Gérald Riverin

Over the past century, exploration methods for volcanogenic massive sulphide deposits have evolved in response to a decreasing number of discoveries made by traditional surface prospecting and by ground and airborne geophysics. Statistical trends support the concept that fewer and fewer outcropping and sub-cropping VMS discoveries will be made in the future. In turn, this creates new opportunities to develop more sophisticated exploration models and techniques to explore at greater depth and to make blind discoveries. Current exploration models include various combinations of geological, geochemical and geophysical criteria which have been based on the results of land-based VMS research. The role of seafloor research in the development of these models has so far been only of a subordinate nature, perhaps due to a lack of direct involvment of the exploration industry in the seafloor research, and vice-versa for the seafloor researchers in VMS exploration. Another contributing factor is that exploration relies on exploration criteria that result from detailed geological, geochemical and geophysical studies of both footwall and hanging wall rocks, studies that are not possible in modern sea floor environments. Nevertheless, seafoor research has contributed to our understanding of the growth of sulphide mounds, the mechanism of sulphide deposition and of the chemistry of fluids involved in VMS systems. In particular, the role of structure and of tectonic setting has been clarified through observation of active seafloor hydrothermal systems. In turn, observations made in land-based VMS research has helped seafloor researchers to focus on key issues which, will eventually contribute to improved exploration models.

Jan 1, 1998

By Sang Joon Pak

Deep-sea mineral resources explored by Korea are categorized into mainly three types; manganese nodules, manganese crusts and seafloor massive sulfides. Manganese nodules have high Pt enrichment factors (EF=400, ore/crust ratios). Rare earth oxides (REO) contents from manganese nodules show from 0.037 to 0.302 REO% with mean value of 0.12%. Te and Pt are highly enriched in manganese crusts, displaying EFs of 10800 and 150, respectively. REO contents of manganese crusts are slightly richer than manganese nodules (0.013~0.387 REO%, average = 0.18 REO%). Seafloor massive sulfides deposits are featured by outstanding values of Se (EF=1300) well as In (EF=110). Au (0.8~26.3 g/t) and Ag (0.9~348.0 g/t) are another enrichment metals in SMS, although they belong to precious metals. Rare earth elements of SMS are meaningless as resources but REE are increasing in sediments overlying SMS. Heavy rare earth elements (HREE) from both manganese nodules and manganese crusts are typically higher than ones from land-based REE deposits. HREO grade and their portions of manganese nodules as well as manganese crusts are greatly similar to ion-absorbed type REE deposits in China, implying REE of subsea mineral resources are absorbed in nodules and crusts. Rare metals including REE could be exploited as by-production of commodities such like Ni, Co, Cu and so on. Rare metal resources from manganese nodules and manganese crusts are featured by low-grade and large scale deposits. Therefore rare metals in subsea mineral resources will add its economic values.

Jan 1, 2011