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By Igor E. Mikhaltsev

This paper concerns the continuation of work on the deepwater non-oxygen cycle heat energy generating systems. The 25-kW prototype of a universal deepwater turbine-electric energy source with hydrazine-hydrate as the primary heat production chemical is described in short and its abilities are discussed. The ?hydrazine-hydrate 64? is a catalytically dissociated heat production chemical (H2H4 ? nH2O) with 36% of water. The system was designed for work in any depths of the ocean down to 6000 m. It was built and tested working in the testing chamber in the ambient hydrostatic pressure of 600 bar. Then it was tested in the autonomous programmed regime in the Atlantic Ocean. The privileges of that energy system for any bottom installations or moving devices designed for ocean mining which need high power energy sources (20-100 kW and more) are discussed. The important needed step forward is raising the efficiency of the system which needs some investigation work in known directions. It is supposed that the possibility of getting about 5 kg/kWh with improved battery charging possibilities could be achieved. This might make the system even more profitable for mining operations.

Jan 1, 2001

By Gregory J. Kurras

In 1995 the Marine Minerals Technology Center (MMTC) of the University of Hawaii conducted a sidescan sonar survey and sampling expedition of the submarine geology and hydrothermal systems surrounding the active volcano White Island. The island is located in the Bay of Plenty, within the geothermally active Taupo Volcanic Zone off-shore of the North Island of New Zealand, and is the site of numerous shallow-water hydrothermal systems. The survey system, an EdgeTech DF1000 sonar, was a dual frequency 100 kHz & 500 kHz sonar capable of imaging the seafloor at better than 1 m resolution and possibly detecting gas bubbles within the water column. Sidescan imagery clearly shows sand channels, debris slumps, submarine landslides, and volcanic ridges all around the island to roughly 800 meters offshore. However, analyses of the both raw and processed acoustic data indicate that the sonar was not able to image any of the shallow-water hydrothermal gas seeps known to exist around the island. Vents were located using a commercial fish finder and knowledge from local tour guides and divers. Eleven gas samples from three different sites were collected by divers for analysis of chemical and isotopic composition. Rock samples were collected from thirteen underwater outcrops for correlation with existing data on subarial island flows sampled by previous investigators. Thin sections and XRF analysis were done for each rock to determine mineral assemblages along with major and trace elements, which were used to tie submarine samples to specific subarial stratigraphic layers.

Jan 1, 2011

By Lars-Kristian Trellevik, Jan Arvid Ingulfsen

Swire Seabed is dedicated to being at the forefront of the Autonomous Subsea Revolution. The company is currently working along and developing operational, technical and market strategies where autonomous technology is the driving force. Swire Seabed’s vessel Seabed Constructor is currently mobilized and operating eight Hugin AUVs and 6 Surface going USVs. This significant and revolutionary spread is owned by Ocean Infinity. Ocean Infinity and Swire Seabed is currently involved in the search for the missing MH370 – in about 3 months the vessel and autonomous spread have fine combed an area of deep sea floor spanning over more the 100 000 km2 . With such a considerable spread with a depth rating of 6000 meter – Swire Seabed and Ocean Infinity is challenging long held paradigms in subsea mapping and resource surveys. Highly accurate and precise data can be acquired for large areas in record time, and at a comparatively much reduced cost. As one earlier required several vessels and associated crews and logistical support – Swire Seabed and Ocean infinity are now able to operate a large number of AUVs and USVs, through technological advances in automatic data-processing and interpretation, from a single offshore vessel. This opens up vast possibilities for emerging markets such as subsea-minerals. Swire Seabed is also developing strong collaborative relationships with academic institutions. Along with UIB Swire Seabed is developing methodology for deep sea geological and geophysical resource searches applying AUVs at an industrial scale – this work is based on UIBs groundbreaking work and significant experience in the same fields. In particular Swire Seabed and K.G Jebsen Centre for Deep Sea Research (UIB) have developed methodologies for conducting detailed Seep-Searches at a large geographical scale. UIB and Swire Seabed is further pursuing a formalized long term relationship for academic and industrial cooperation and exchange in AUV operation and methodology development. Whilst K.G Jebsen Centre for deep sea research have been involved in basig deep sea research for years, Swire Seabed have specialized in cost-effective heavy duty operations in water depths greater the 3500 meters. This collaboration affords the subsea mining community a unique pool of both insight and operational capacity.

Jan 1, 2018

By S. E. Boyd

Studies of benthic recolonization following the cessation of dredging in U.K. waters and elsewhere are limited, and are largely confined to experimental circumstances. Investigations of the physical and biological status of licensed areas in the U.K. at various times following cessation of commercial dredging are very limited and so judgments as to the likely progress towards environmental restoration and the time-scales are often based on predictions rather than real data. This study was established to address this deficiency by assessing the status of seabed substrata and associated benthic fauna within and outside areas where dredging had ceased and to conduct follow up sampling to monitor progress towards full recolonization.

Jan 1, 2004

By Siân E. Boyd

Studies of benthic recolonization in the aftermath of marine aggregate dredging in the U.K. and elsewhere are limited and are largely confined to experimental circumstances. Investigations of the physical and biological status of licensed extraction sites in the U.K. at various times following cessation of commercial dredging are very limited, and so judgments as to the likely progress towards environmental restoration and the time-scales involved continue to be based on predictions rather than real data. This field-based research programme was commissioned to enhance the understanding of processes leading to physical and biological recovery of the seabed following dredging, thereby aiding the identification of practices to minimize environmental harm at licensed sites, and to promote rehabilitation on cessation. The outcome of survey work will have the notable benefit of allowing questions about the present status of locations hitherto subject to commercial exploitation to be answered directly, rather than by inference.

Jan 1, 2002

By Brian Parsons

In June of 2013, Odyssey Marine Exploration conducted sea trials of the newly installed SeaBat 7150 full-ocean multibeam sonar system on the M/V Dorado Discovery over the Fierberling Guyot in the northeast Pacific Ocean. Fieberling Guyot is located approximately 990 kilometers west of San Diego, California and it rises abruptly from the deep ocean floor (~4300 meters) to a minimum depth of approximately 438 meters. The SeaBat 7150 operates at two distinct frequencies, 24 kHz (shallow to 3000 meters) and 12 kHz (full-ocean depth greater than 2000 meters). Onboard operational data are managed by a suite of state-of-the-art software. A SQL Server 2012 database provides the highly specific management and visualization tools as ArcGIS 10, Micromine 2013, and Geobank 2013 database. The 7150 is mounted on a gondola one meter lower than on previous system and greatly reduces bubble interference. The 7150 generates 880 beams

Sep 14, 2011

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 Sven Petersen

In April 2010 three REMUS6000 series autonomous underwater vehicles (AUVs) have been used to simultaneously map large areas near the Mid-Atlantic Ridge (3°N) axis in water depths ranging from 1,000m to 4,000m. One vehicle was provided by the Leibniz-Institute for Marine Science, IFM-GEOMAR (Kiel, Germany) the other two were provided by the Waitt Institute for Discovery (La Jolla, USA) and managed by the Woods Hole Oceanographic Institute (USA). The REMUS6000 vehicles, manufactured by Hydroid Inc. (USA), are "cigar-shaped" vehicles (4m long and weighing approx. 900kg) and consist of a tapered forward section, a cylindrical midsection and a tapered tail section. An internal titanium strongback, which extends through much of the vehicle length, provides the structural integrity and acts as a mounting platform for syntactic foam, equipment housings, various sensors and release mechanisms. The AUVs can be used in various payload configurations such as multibeam bathymetry, electronic still camera, or subbottom profiler. For these missions the electronic still camera configurations was installed. An EDGETECH 2200M dual frequency (120/410 kHz) side scan sonar was used to map the seafloor, but other frequencies are readily available for more options in resolution and range. The 120 kHz side scan transmitter was used for most missions in order to map large areas (increased range) and to be able to fly at higher altitudes (between 70m and 90m) above the rough seabed encountered in this area. The maximum slant range was between 600m and 700m on both sides resulting in a swath width of up to 1.2 km. Line spacing ranged from nearly 1,000m in flat areas down to 400m in steep terrain. Side-scan mosaics were generated with a 1m resolution. Selected areas were targeted by the higher resolution 410 kHz transmitter as well as by bottom photographs flying as low as a few meters above the seabed. The vehicles navigated autonomously using a combination of inertial navigation (Kearfott T-24 or T-16 INS) and long baseline acoustic navigation by computing their range to two moored acoustic transponders. Working efficiently in this rough topography at speeds above 3 knots was only possible due to the obstacle avoidance capabilities of these AUVs.

Jan 1, 2011

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

Jan 1, 2011

By T. Semkova, G. Cherkashov, V. Rashidov, L. Anikeeva, G. Gavrilenko, G. Glasby

The Kurile Arc consists of at least 100 submarine volcanoes and 5 submarine calderas located mainly in the rear arc (Figure 1). The arc is seismically very active, particularly in the south, and is characterized by extensive volcanism and hydrothermal activity. At least one subaerial volcano on the arc (Medvezhy located on Iturup island) has an extremely shallow magma chamber and is intensely active.

By LeRon E. Bielak

Public Law 103-426 was signed into law in October 1994. Its provisions amended sections 8(k) and 20(a) of the Outer Continental Shelf Lands Act (OCSLA). The 8(k) amendment provides the Secretary of the U.S. Department of the Interior 001) with new discretionary authority to negotiate agreements for using Outer Continental Shelf (OCS) sand, gravel, and shell resources for certain projects of public benefit (e.g, beach, shoreline and coastal wetlands restoration that are under- taken by a Federal, State or local government agency). The new law also covers construction projects that are funded wholly or in part or authorized by the Federal Government. Under the law, the Secretary may assess a fee for use of the resource by taking into consideration the value of the resource and the public interest served. The law also requires that any Federal agency proposing to make use of OCS sand, gravel, or shell resources enter into a Memorandum of Agreement (MOA) with the DOI. An MOA would promote efficient coordination and resolution of inter- agency scheduling and issues. The law requires that Congress be notified before use is made of these OCS resources. The amendment to section 20(a) of the OCSLA clarifies that obligations concerning environmental studies extend to non- competitive lease situations and includes minerals other than oil and gas. The Minerals Management Service (MMS) is the DO1 agency responsible for interpreting and implementing the provisions of Public Law 103-426. The negotiated agreement approach is distinctly different from the competitive bidding requirements that have applied to all OCS minerals since the inception of the OCSLA. The MMS has opted to implement the new law in a nontraditional manner. Rather than issuinga body of new regulations to cover the negotiated agreement situation, or attempting to amend three sets of existing regulations, MMS is pursuing a less formal approach of providing guidelines. More weight is placed on the negotiation process itself and the legal agreement that consummates the process as the means for establishing ground rules, terms, and conditions under which qualifying projects may be conducted. This process must recognize and adhere to requirements of other laws, including the National Environmental Policy Act.

Jan 1, 1995

An extensive ferromanganese nodule field south of New Zealand (Fig. 1) has existed beneath the flow of the Deep Western Boundary Current (DWBC) and Antarctic Circumpolar Current (ACC) for at least the past 15 m.y. West of 174°E, between 59°S and 48°S, the field is 300-500 km wide, but east of 174°E, where current flow impinges on the eastern slope of the Campbell Plateau, the field narrows from ca. 200 km at 55°S to ca. 120 km at 51°S. This narrowing coincides with deflection of current flow eastwards, and consequent reduction in bottom-current velocity and eddy kinetic energy. Based on sea floor photographs, dredge samples and 3.5 kHz profile data, six distinct seafloor substrates are delineated, forming broadly parallel zones eastwards from the lowermost Campbell Slope (Fig. 2).

Jan 1, 2003

By Charles L. Morgan

In a commercial effort to characterize deep seabed manganese deposits in the Clarion-Clipperton region of the northeastern tropical Pacific, Ocean Mineral s Company carried out 16 expeditions to the region between -1978 and 1981. During these cruises OMCO collected substantial data. Activities included acoustic profiling, video and photographic imaging of the seabed, and sampling of the deposits with dredges, box cores and free-fall grab samplers. In 1990 the samples, photographs, technical reports and computer data bases which resulted from this work were archived at the Marine Minerals Technology Center at the University of Hawaii. This preliminary examination of the collection focuses on the biological observations made from almost 10,000 photographs of the seabed and the manganese nodule size distributions and compositional data from the free-fall grab recoveries. Regional trends are evident in all three data types. The biological examinations of the seabed photographs show significant geographical trends, with greater abundances of organisms being noted in the northeastern extreme of the region, decreasing toward the southwest (11.4 to 2.7 observations per 100 m2; 460 to 190 g per 100 m2). The nodule size distributions suggest that the ratio of the nodule burial rates to growth rates systematically decreases over the same range (0.65 to 0.36 nodules buried per 1 cm of growth). Preliminary geostatistical analysis of the ore grade data show that, in addition to high local variability, some deposit

Jan 1, 1991

By Peter A. Rona

The recent discovery of the first black smoker-type hydrothermal venting and massive sulfide mineral deposits at a site in the rift valley of the slow-spreading Mid-Atlantic Ridge near latitude 26°N, longitude 45°W (Rona et al., 1986, Nature, 321: 33-37), demonstrates that a complete series of hydrothermal mineral deposit types exists at slow-spreading oceanic ridges (half-rate = 2 cm/y), similar to the series previously known at faster-spreading oceanic ridges (half-rate > 2 cm/y). The largest hydrothermal mineral deposit known at a seafloor spreading center is a stratiform massive sulfide body with bulk dry weight of about 100 x 106 metric tons in the Atlantis II Deep at the slow-spreading axis of the Red Sea. This observation invalidates the concept that size of a hydrothermal deposit is directly proportional to rate of seafloor spreading. Instead, the occurrence, grade and size of a hydrothermal deposit formed at a seafloor spreading center is controlled by anomalous chemical and physical conditions which may occur at extremely localized sites at the full range of spreading rates. The basic hydrothermal process involving subseafloor hydrothermal convection driven by magmatic heat sources appears to be similar at slow- and faster-spreading centers. However, differences exist in the periodicity of magmatic cycles that energize hydrothermal circulation (104 y at slow-spreading centers; 103 y at faster-spreading centers); in the distribution of hydrothermal sites along a spreading axis (estimated 100 km along slow-spreading centers; 10 km along faster-spreading centers); and in residence time

Jan 1, 1986

By Robert R. Tarver

A long history of gold production at Nome, Alaska has resulted in long term interest in the nearshore environment as a production target. Mining by Western Gold Exploration and Mining Company offshore of Nome yielded approximately 100,000 troy ounces of gold in the period 1986 through 1990. This study was designed to determine the relationship between heavy minerals, sediments, and gold concentrations which occur in the upper meter of sediment offshore of Nome. Standard procedures were implemented for grain size analysis, heavy mineral separations, and heavy mineral frequency determination.

Jan 1, 1991

By James R. Herring

An unusual combination of ten new, deep (-100 m) coreholes and an extensive high-resolution seismic reflection network enables us to produce a detailed study of the phosphorite resources in the Tertiary strata of the Georgia continental shelf. These strata are mixtures of a terrigenous facies, notably quartz and clay along with minor amounts of other aluminosilicate minerals, and of a marine facies, notably phosphorite and carbonate. Phosphatic sediments occur throughout the cores, however the richest phosphorite beds are in the middle Miocene (Serravallian) sediment, where they constitute up to 70 percent of the sediment mass. Major zones of phosphate enrichment occur chiefly at major unconformity boundaries (tops of Oligocene, lower and middle Miocene, upper Miocene, and lower and upper Pliocene) and at prominent intrastratal reflectors representing minor unconformities within units. Phosphorite co-occurs with the clay minerals, especially palygorskite, but correlates inversely with carbonate and detrital quartz, indicating a low-energy depositional environment. The clay minerals present in these strata, which have an environmental consequence on recovery of the phosphorite, are varying concentrations of smectite, kaolinite, mica, palygorskite, and sepiolite. Phosphatic resources have been determined within only the Miocene strata. Sediment volume for this unit to the 100 m isobath on the continental shelf has been established using the high-resolution seismic reflection network that has been calibrated using the deep coreholes. Phosphorite grains larger than 0.1 mm average about 40% of the sediment. In turn, most of the remainder of the sediment in this size range is quartz, which is separable from phosphate grains using conventional flotation techniques. Our estimate is that 300 Gt of phosphorite lie within the Miocene strata of the Georgia continental shelf.

Jan 1, 1994

By Freddy Pøhner

The paper describes recent advances in the technology for mapping of the seabed with acoustic instrumentation. These instruments are typically single beam echo sounders, multibeam echo sounders and high resolution sub bottom profiler. For the single beam echo sounders, new features for deep water mapping are described, as well as the possibility for combining investigation of shallow areas with side scan sonar and vertical echo sounding in the same instrument. Multibeam echo sounding technology for deep and shallow water is reviewed, and some new high resolution instruments using dynamic beam focusing is presented. The sediment profiling technology deals with a novel design for high resolution sub bottom profiling, based upon a Mills Cross transducer with resolution as good as 3 degree in its largest configuration and a frequency range of 2,5 ? 7 kHz. Remarkable features of the system are a very high ping rate even for deep water, and the capability to map buried objects or structures by several simultaneous beams. Some results obtained with the first installation on the French research vessel ?Beatemps Beaupré? are presented.

Jan 1, 2003

By Richard C. Newell

The United Kingdom marine aggregate mining industry is the second largest of its kind after Japan. Materials for the construction industry, sea defences and for many other purposes are exploited from shelf waters at depths of 30-50 metres by self-contained suction dredgers which often screen material to obtain a cargo of a particular quality. Assessment of the environmental impact of such mining activities both within the boundaries of the dredged areas, and in the zone of deposition of outwash from the dredger has in the past been mainly based on predictive models based on the settlement rates of the individual particles and assumed Gaussian diffusion principles during the settlement phase. Recent studies which we have made on both the mass balance for materials rejected during the dredging process and direct measurements of the settlement of material in the dispersing plume suggest that the zone of settlement is much less than that predicted from diffusion models. Instead of a downstream settlement plume of 10-20 km in the tidal currents of U.K waters, our measurements show that inorganic components of the dredger plume reach background levels in the water column within 880 metres.

Jan 1, 2000

By Mark D. Hannington

Seafloor polymetallic sulfides have been found in diverse volcanic and tectonic settings on the ocean floor at water depths ranging from 3700 meters to <1500 meters. More than 100 occurrences of hydrothermal mineralization have been documented (including Fe-oxide deposits, Mn-crusts, metalliferous sediments, and massive sulfides), but high-temperature hydrothermal activity and large accumulations of polymetallic sulfides are known at fewer than 20 different sites. Chemical analyses of samples from these deposits indicate that they contain important concentrations of Cu, Zn, Ag, and Au, comparable to those of massive sulfide deposits on land. However, the lack of sufficient data concerning the distribution, size, and bulk composition of seafloor deposits precludes a meaningful assessment of their resource potential.

Jan 1, 1994

By Tetsuo Yamazaki

Deep-sea rare-earth element-rich mud (REE Mud) distributes in pelagic clayey sediment column on ocean seafloor at 4,000-6,000 m deep. The thickness ranges 5-80 m and the burial depth 0-100 m. The REE content ranges 600-2,250 ppm in Pacific and one of the richest, maximum 6,500ppm, has been found in Marcus Is. exclusive economic zone. By applying a conventional hydraulic excavation and lifting methods, the economy of REE Mud mining around Marcus Is. is preliminary examined. Because the waste content in REE Mud is high and the disposal cost in Japan is very expensive, the mining is recognized far away from economy.

Sep 14, 2011