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By RB. Pedersen, T. Barryere, E. Reeves, A. Stensland, I. Thorseth, T. Baumberger

Venting on ultraslow spreading ridges is far more abundant then previously predicted, and the discrepancy between observed and predicted vent field density may imply that non-magmatic heat sources are common along these ridges (Baker and German, 2004; Escartin et al., 2008; Rona et al., 2010; German et al., 2016). In this study we have estimated the flux from two hydrothermal vent sites situated on the slow to ultraslow spreading Mohns Ridge at the Arctic Mid-Ocean Ridge system (AMOR). The flux estimates have been made using the primordial isotope 3He in the non-buoyant plume above the Loki’s Castle vent field at the northern termination of the Mohns Ridge, and from the Jan Mayen vent fields area situated close to the southern termination of the ridge. Primordial 3He enters the oceans through degassing and mixing with hydrothermal fluids eventually to be discharged at the ocean floor primarily at hydrothermal vent sites and submarine volcanic eruptions (e.g. Clarke et al., 1969; Lupton and Craig, 1981; Lupton, 1998). Once introduced into the water column the concentration will only decrease by dilution due to its conservative behavior in the water column. Water column samples were collected using a CTD (conductivity, temperature, depth) probe (911plus Seabird) with a Niskin water bottle rosette. The water column above the Jan Mayen vent fields (JMVF) was sampled in the years 2006, 2011, 2012 and 2013 (82 samples) and the water column above the Loki’s Castle vent field was sampled in the years 2007, 2008 and 2009 (116 samples).

Jan 1, 2018

By B. J. Bluck

Diamond mega-placers, in order to rank amongst the primary diamond deposits, are defined as => 70 m carats at =>95% gem quality. There is only one mega-placer known and that is found along the coast of southwestern Africa fringing the Kaapvaal craton. Placers are classified as residual when they are left on the craton, transient when being eroded into the exit drainage and terminal. Terminal placers, in being the final depositories of diamonds off the craton, have the greatest probability of being a mega-placer and such is the case in the placer deposits near the Orange River mouth, southwestern Africa. There are four main groups of conditions leading to the development of a mega-placer: the craton, the drainage, the nature of the environment at the terminus and the timing. The craton, in its role as the producer of diamonds is significant in respect to its size, diamond-fertility, the degree to which diamonds from successive kimberlite intrusions have been retained there and their availability to the final drainage yielding the mega-placer. Cratons in being buoyant have a tendency to leak diamonds into surrounding basins but in being incompressible often have orogens converge onto them resulting in lost sediment being returned as foreland basin fills. In order to concentrate a bulk of diamonds the drainage basin has to be large with a high proportion of it on the craton. The drainage yielding the mega-placer should ideally not have been preceded by older drainage and other systems that may have robbed the craton of earlier diamonds. The exits of diamonds from the craton need to be few in order to focus on their supply and the drainage network needs to be efficient in order to remove the maximum volume of diamonds off the craton. This efficiency and the focused termination is best achieved by the rejuvenation of a pre-existing drainage network. The drainage should be young enough to yield host sediments friable enough to allow brittle diamonds to be recovered from them.

Jan 1, 2004

By Graham Singleton

Around 235 million tonnes of marine aggregates have been dredged in the last decade from the UK continental shelf alone. The current distribution of marine aggregate production licence areas in North West Europe reflects the relationship between a variety of factors such as the natural distribution of deposits of sand and gravel, the demand for aggregates, the technical capabilities of the dredging fleet and environmental considerations. Whilst the sand and gravel deposits targeted by the marine aggregate industry are generally relict and therefore geographically fixed, the remaining factors have evolved over time and will continue to do so in future. Applications for new licences must not only reflect the current situation, but anticipate future trends. The main markets for marine aggregates are the construction industry, centred around the larger centres of population and coastal protection projects along the coastline of Europe. The aggregate industry as a whole does not create demand but simply meets it. Many factors influence the overall demand for aggregates and guidance exists for those in authority and industry who need to plan for the supply of aggregates. Adequate supplies should be maintained at the best balance of social, environmental and economic cost, whilst ensuring that extraction and development are consistent with the principles of sustainable development.

Jan 1, 2004

By Dan Johnson

The discovery of rich alluvial diamond deposits on Namibia?s Skeleton Coast in 1908 began a period of intense exploration and mining off the coastal sand; and shallow surf zones. In the mid-60s a Texas entrepreneur, Sam Rollins took the search to the seafloor. The inhospitable conditions encountered made the early going difficult. After a slow start, the past 10 years have seen much progress in geologist?s understanding of the deposition mechanics and the use of sophisticated geo-physical and sampling techniques to aid in the discovery of economic deposits. Diamondfields, in a joint venture with BHP and Benguela Concessions, began an exploration program in 1994 for sea-bed diamonds off the Port of Luderitz in Namibia. This program has progressed to a mine development program with the potential of creating a 500,000 carat per year operation. The mining technologies being considered include state-of-the-art, remotely operated sea-bed crawlers and high volume dredges feeding to semi-mobile processing platforms. The company's objective is to use the best proven technology to create an environmentally responsible operation with the lowest fixed operating costs and the longest and safest weather operating window of any offshore operator working Africa's diamond coast.

Jan 1, 1998

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 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 Boris Broere, Wiebe Boomsma, Pieter Lucieer

"The Blue Nodules project started February 2016 as part of the EU Horizon 2020 subsidy program. Blue Nodules aims at developing a sustainable deep sea mining system for the harvesting of polymetallic nodules from the sea floor. Blue Nodules is closely related to the Blue Mining and Midas projects, both EU subsidized projects. Blue Mining mainly concerned the development of technical capabilities to adequately and cost-effectively discover, assess and transport deep sea mineral deposits up to 6,000 m water depths. The MIDAS project - Managing Impacts of DeepseA reSource exploitation - was a multidisciplinary research programme investigating the environmental impacts of extracting mineral and energy resources from the deep-sea environment.The Blue Nodules project is divided in seven work packages defined to develop mining equipment and process equipment, to assess and integrate environmental, economic and technological aspects and to assess and minimize the environmental impact of mining polymetallic nodules.This abstract will address part of the work performed in the second work package called: ‘Subsea harvesting equipment and control technology’. The main topic addressed will be the development of a propulsion system to manoeuvre the harvesting system. The propulsion system will be developed with full incorporation of economical and compliance requirements and to have a minimal environmental impact.SummaryBased on information gathered in the 70’s during the first studies into polymetallic nodules mining and more recent data and developments, an initial full scale design of the propulsion system is developed. The largest challenge for the propulsion of a deep sea mining vehicle is to drive on the soft sediments associated with these deep sea environments. A short summary of the initial design criteria is given below."

Jan 1, 2017

By Jeremy Spearman, Alan Cooper, Mark Lee, Jon Taylor, Michael Turnbull, Neil Crossouard, Bramley Murton

"SUMMARYSeamounts are underwater mountains caused by volcanic activity. They are of great oceanographic interest because of their local and basin-scale influence over ocean systems, their often unique ecosystems, and because they are associated with the formation of ferromanganese (Fe-Mn) crusts. These crusts are of particular interest to scientists because they are rich in some of the rare elements increasingly required for development of renewable technologies. When the possibility of mining such seamounts is considered, an inter-disciplinary study of seamount hydrodynamics, crust formation and ecosystem sensitivity is required. MarineE-tech is one such multi-disciplined project that has been commissioned to address these different aspects in order to improve understanding of the viability and desirability of mining Fe-Mn crusts. This paper describes a key part of this study, namely the development of a model, informed by hydrographic observations, of the currents around one such seamount and the in situ validation of a sediment disturbance plume model as a pre-cursor to assessment of the potential effects of mining activity.INTRODUCTIONFerromanganese crusts are thought to form by precipitation of iron and manganese oxides from oxygen depleted mid-water known as the oxygen minimum zone (OMZ). Oxidation rich waters, typically at depths of about 800-2200 m (Hein et al, 2000). This range of depths coincides with the flanks and summits of many seamounts. The ferromanganese crusts found on seamounts have been found to have high concentrations of rare elements, like Tellurium, that are considered critical to low-carbon energy production. Seamounts are complex environments: in terms of the local hydrodynamics that tend to trap water over the seamount due to the Taylor Cap effect (e.g. Chapman and Haidvogel, 1992) and which can enhance the productivity of seamount waters through upwelling (Lavelle and Mohn, 2010), in terms of the microbiological activity that leads to the precipitation of the Fe-Mn crusts, and also in terms of the often unique ecosystems that are the product of the “island” nature of seamounts and the upwelling of nutrients. The understanding of this complexity is a necessary journey towards the realization of viable, yet environmentally responsible, mining schemes. The formation of crusts will be influenced by the local (and larger-scale) hydrodynamics. The exploration of promising crust sites could be made much more efficient by understanding where the most prospective deposits are likely to occur. Knowing how to remove these crusts without impacting significantly on the local environment will be a pre-requisite for such mining to be acceptable to the public and funders alike."

Jan 1, 2017

By Sang Bum Chi

In order to better predict and manage benthic disturbance by deep seabed manganese nodules mining, we needed to conduct a benthic disturbance experiment at the selected area, which has a similar environmental condition as the preservation reference area. Therefore, we have performed environmental baseline studies from 2003--not only to select the benthic environmental impact testing site but, also to detect any environmental changes before and after mining activity. Since then, a large dataset of various parameters ranging from physical (e.g. temperature, salinity, current, weather), chemical (e.g. dissolved oxygen, nutrients, dissolved and particulate organic carbon), biological (e.g. bacteria, plankton, benthos), geological (e.g. Mn-nodule abundance, sediment shear strength) and others (e.g. bathymetric profile and slope, mass flux) have been accumulated. Using this dataset, descriptive statistics and cross-correlations were performed to select the benthic environmental impact testing site. Outcome of this analysis suggests that the potential benthic impact testing site would be a rectangular-shape area (10 km × 10 km) and located at 10°27'~10°33'N, 131°53'~131°58'W, which is latitudinally the same as the preservation reference area.

Jan 1, 2011

By William D. Siapno

Approximately a century lapsed between the time nodules were discovered and the beginning of commercial exploration in the early 1960's. A period of rapid development of exploration and mining technology ensued over most of the next two decades. In recent years advancement has been sharply curtailed. This paper discusses the constraints inhibiting nodule mining and some developments that could aid in overcoming certain difficulties. Specifically, the greatest single constraint is economic. With few exceptions mineral markets are badly depressed. Present projections for development of nodules are for the late 1990's or beyond. However, the U.S. awarded exploration licenses in mid-1984 and more recently boundaries of license areas have been released. These conditions promote cooperation among organizations engaged in deep ocean mining. Survey data, and where appropriate some data products, have been exchanged between various consortia. The present hiatus in at-sea activities provides an excellent opportunity to investigate the best means to proceed. This period of quiescence offers a rare moment to distill the meaningful values of an era of hectic activity to permit more efficient development in the future.

Jan 1, 1985

By David A. Larson

The future exploitation of crust deposits will require a dependable characterization system. The U.S. Department of the Interior, Bureau of Mines (Bureau) initiated research to develop a new sampling dredge by conducting a series of cutting and physical property tests on previously collected cobalt-rich manganese crust and substrate samples. Using the engineering parameters derived from these tests, a large, heavy dredge was designed and tested. This heavy dredge was capable of fragmenting and collecting in situ crust, but it created handling problems for the research vessel, thus an aggressive cutting, light-weight dredge was conceived and fabricated. The light-weight dredge is capable of fragmenting and collecting crust and some talus. This dredge can be used on flat or rough seabed terrains. It can be easily retrieved from hang ups and reset to sample again.

Jan 1, 1991

By Tim J. Boyd

Gregg Marine, Inc. (headquartered in Signal Hill, California) has recently introduced an innovative seafloor drill system for offshore geotechnical site investigation and seafloor mineral exploration. The system is capable of working in water depths of up to 3,000 meters and is rated to drill to a depth of approximately 150 meters below mudline. The remote operated system integrates established drilling technology with proven Schilling telemetry and controls. The flexible nature of the patented wireline drilling technology enables the use of standard sampling systems (up to PQ-size core and 3? thin-walled tubes) as well as downhole testing systems (including CPT testing, vane shear testing, downhole sensors and borehole geophysical tools). The modular nature of the seabed drill system and the accompanying launch and recovery system (LARS) enables the use of local vessels of opportunity for projects resulting in reduced project costs and improved mobilization responsiveness times. Keywords: seafloor, seabed, geotechnical, drill, drilling, core, coring, sampling, CPT, cone penetration testing, borehole, logging, survey, exploration, ROV, remote sensing

Jan 1, 2011

The chemical composition of the nodules varies with the type of manganese minerals and the size and characteristics of their nucleus but those who have an economic interest have nucleus, generally : Mn> Fe> 6> Si> Al> Ba> Ni> Cu > Co. The Pacific Rim is an area of abundant occurrence of polymetallic nodules and the Pacific sea floor of the Clarion-Clipperton Zone (CCZ) is one of the most interesting areas in regard to the genesis of polymetallic nodules. Their abundance in the ocean floor is very variable, as there are places where they cover more than 70% of the ocean floor. The nodules can be found at any depth, but the highest concentrations are between 4000 and 6000. Hydrothermal processes that occurs near the East Pacific Rise at 21° N, may inputs metallic elements to nodules and to pelagic sediments, especially in regions close to the dorsal, as a greater influence hydrogenetic processes are present westward Metals such as Cu, Co, Ni, Sn, Fe, Mg, Pb, Zn and Ba show a relationship with the East Pacific hydrothermal activity and sea currents carry these metals in solution to the Clarion-Clipperton fracture area, where there are hydrogenic metals sources (Al, Fe and Mn).

Sep 14, 2011

By Glen Smith

Nautilus Minerals, the world?s leader in exploration and development of deep ocean seafloor resources, is today focused on the recovery of high-grade copper and gold in seafloor massive-sulphide mineralization. These targeted mineralized belts, analogous to land-based volcanogenic massive sulphide deposits, are located near plate boundaries in the back arc basins of the Western Pacific. The first deposit to be developed by the company is located at a depth of 1,600 meters at Solwara 1, in the benign waters of the Bismarck Sea. This location lies within the territorial waters of Papua New Guinea. From 2006 to 2009 the company completed detailed environmental and geological studies at Solwara 1, culminating in a number of world firsts, including the first Environmental Permit granted for the extraction of seafloor massive sulphide deposits and the first NI 43-101 compliant seafloor massive sulphide deposit resource statement. Nautilus has relied heavily on proven deepwater technologies from the oil and gas industry in the design of its production system. Pipeline trenching units, workclass ROVs, deepwater production risers and drill cuttings removal systems will be adapted to initiate this new and exciting industry. Key contractors used by Nautilus on this innovative project have all been selected for their deepwater experience (gained in the oil and gas industry), creativity and determination to launch this new industry successfully. Innovation is at the forefront of Nautilus? success to date. This paper summarizes the progress to date of this development which will provide a new source of minerals for the world and which will contribute to sustainable growth for the future.

Jan 1, 2010

By T. Schoening

The exploration of the seafloor regarding the abundances of poly-metallic nodules has received growing attention recently. Image-based exploration using cameraequipped deep-sea observation systems has been introduced successfully to increase spatial resolution in the exploration process but the evaluation and interpretation of the huge amount of image data creates a serious bottleneck. In this paper we present a new software solution to the problem of automatic detection and segmentation of poly-metallic nodules in underwater images, which is not only accurate but so fast that real time image analysis is definitely in reach. Thus, an application on an AUV (Autonomous Underwater Vehicle) seems possible in the near future.

Sep 14, 2011

By M. Geoghegan

Under the provisions of the U.N. Law of the Sea Convention Ireland is likely to have mineral rights to an area of continental shelf some six times its present land area. Apart from the major potential hydrocarbon basins which are currently the focus of active commercial exploration, little is known about the mineral resources of this vast area. In recent years a variety of mineral resources however have been identified from the coastal region. These include Sand and Gravel aggregates, Calcaraeous Algae (Lithothamnion), Heavy Mineral Sands and Coal deposits. The potential also exists in the coastal zone for buried placer deposits and base metal deposits. Several million cubic metres of gravel and hundreds of millions of cubic metres of sand have been identified by the Geological Survey of Irelands (G.S.I) Marine Unit off the east coast. The greater part of these deposits lies within the 10 metre depth contour and are easily recoverable. Irish aggregate needs at present are well supplied by onshore Pleistocene glacial deposits. Commercial interest in offshore deposits is in supplying coastal areas which are locally poor in aggregate and major coastal construction works. The possibility of supplying the large British and Continental European Market nearby also exists.

Jan 1, 1988

By W. C. Burnett

The land phosphate deposits of the U.S. southeastern coastal plain have long been a major factor in the world trade of phosphate rock (Fig. 1). As recently as 1979, deposits of North Carolina and Florida alone accounted for about 33 percent of the entire world's phosphate exports. This situation is changing, however. World production increased by ~9 %, yet the U.S. share was down to ~28% in 1984. A complex interaction of economic and political factors combined with increasing costs of raw materials, production, and transportation have led to this systematic erosion of the U.S. market share. Changing land-use patterns within the southeast, environmental pressures, exhaustion of shallow high-grade resources in Central Florida, and the increased pressure from expanding low-cost production in other countries throughout the world account for much of the present difficulty in the U.S. phosphate industry. Considering this depressed environment -- what are the prospects for development of offshore resources? A summary of new research on offshore phosphorite within the U.S. Exclusive Economic. Zone (EEZ), as well as an attempt to place possible development of these resources within the current economic setting, is the purpose of this presentation. We will emphasize work in progress on a major offshore deposit along the U.S. Atlantic Margin as well as new research on Pacific Ocean occurrences of phosphorite on seamounts and insular slopes within U.S. waters.

Jan 1, 1986

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 Richard Harrison, Frank Lim

Deepsea Mining will soon become a reality with Nautilus Minerals getting their equipment ready to mine SMS at Solwara 1 off the coast of Papua New Guinea. The vertical transport system (VTS) adopted by Nautilus consists of a riser hanging ‘freely’ from the mining production vessel with a lifting pump unit suspended at its lower end. A compliant jumper connects the pump to the seabed crawler without restraining its movements. In this free-hanging VTS arrangement, the vessel can be re-positioned to follow the crawler should it want to extend the mining area and start stretching the jumper. A recently proposed alternative to this is a free-standing VTS whereby the riser is grounded on the seabed with a base and maintained in an upright position by distributed buoyancy modules or a buoyancy tank at the top. A compliant jumper connects the seabed crawler to the riser base, and another connects the riser top to the vessel. In this free-standing arrangement, the entire VTS can be lifted clear of the seabed for relocation to a new mining area. This paper will describe the important features of the two options and discuss the advantages and disadvantages in respect of riser dynamic behavior, water depth, weather and mining windows, pump maintenance, installation and retrieval, continency measures, etc. The two systems will also be appraised separately for mining SMS and SMnN deposits.

Jan 1, 2018

By S. Jeffress Williams

The topic area for this paper covers the United States portion of the northern Gulf of Mexico, extending from the Rio Grande delta east to the Florida peninsula. Declaration of an Exclusive Economic Zone in 1983 expanded Federal economic jurisdiction on the continental margins from 12 to 200 nautical miles seaward from the coast. The nation-wide area of the EEZ totals 3 million square nautical miles, with approximately 186 thousand square nautical miles in the Gulf of Mexico. In the Gulf, the continental shelf has an area of 81 thousand square nautical miles, extending to a depth of 600 ft. and having widths of 6 to 120 nautical miles. Specific areas on the shelf offer the greatest potential for containing aggregate and other hard mineral resources. The primary geomorphic features along the Gulf coast include: barrier islands, chenier plains, tidal inlets, bays and lagoons, estuaries, and deltaic headlands. These features are composed of terrigenous siliclastic sediments, except for the west Florida coast, south of 29°N latitude, which is dominated by carbonate sediments. On the shelf, the primary features are linear sand shoals and associated sand sheets, relict delta lobes and channels, and banks related to salt diapirs and coral reefs. The composition and distribution of sediments in these coastal and shelf features are determined by numerous geologic factors including: seabed topography; riverine sediment discharge; sediment dispersal patterns due to currents, waves, storms and tides; tectonics and subsidence; and repeated fluctuations in sea level.

Jan 1, 1986