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By Satya Nandan

• A review of the structure and mandate of the Authority – its main functions. • The different types of mineral resources found in the deep seabed – their global distribution. • The Development of Regulations for Prospecting and Exploration of Polymetallic Nodules, Cobalt-Rich Crusts and Polymetallic Sulphides including environmental regulations and guidelines. • Early constraints for deep seabed mining – Improving conditions for mining – Future prospects for mining.

By Ye Jun

Until now, more than 200 sites of sea-floor hydrothermal activities are known on the midocean ridge but few of them are documented on South Mid-Atlantic Ridge (SMAR). This on some extent restricts our directly understanding of the hydrothermal mechanism on SMAR. In 2011, During the Cruise 22 of R/V Dayangyihao, a masive sulfide field was discovered in the center part of the first-order ridge segment that bounded between Cardno Fracture Zone and Saint Helena Fracture Zone, near 15.16°S/13.35°W, which give us an opportunity to recognize the mechanism of hydrothermal systems on SMAR directly. This newly discovered hydrothermal field, which informally called SMAR 15°S, is situated in a SE-NW offset depression of an axial neovolcanic ridge, with water depth of about 2793m. In the water column around this field, strong turbidity and temperature anomalies were detected. Ten meters high venting chimneys, hydrothermal mounds as well as a large amount of hydrothermal vent shrimps were also observed and recorded by ROV and Deep tow camera on the ocean floor. The samples we collected from this field include sulfide chimney fragments, massive sulfides and basaltic rocks. In this study, we are focusing on the mineralogy and sulfur isotope geochemistry of sulfide samples for preliminarily uncovering the geological characteristics and hydrothermal processes of this hydrothermal field.

Sep 14, 2011

By David A. Clague, James R. Hein, Robert W. Embley, Robert C. Vrijenhoek, Randolph A. Koski

We report preliminary results for a group of unique samples collected with MBARI’s ROV Tiburon on August 12, 2005. The samples were collected from the East Blanco Depression (EBD) diffuse-flow hydrothermal field, which was determined in a previous study to cover an area of at least 100 m by 80 m (Hein et al., 1999). The survey reported on here extends that field to more than 1500 m in an approximately N-S direction. The EBD, a pull-apart basin, occurs near the western end of the Blanco Fracture Zone (BFZ), which connects the Juan de Fuca and Gorda Ridge spreading centers (Fig. 1). The samples were collected from a waterdepth range of 3343-3380 m.

Aug 24, 2006

By Alexander Malahoff

Mineral zonation studies were conducted on hydrothermal vents of two hot spot volcanoes. One study site is located within the Axial Caldera of the axial hot spot volcano of the Juan de Fuca Ridge. The young high-temperature hydrothermal vent field consisting of two polymetallic sulfide chimneys, five meters high, located at 130°01.5'W, 45°56.5'N, along a fault complex at the base of the southwestern wall of Axial Caldera was sampled during four ALVIN dives in 1983. Temperatures of up to 270°C were measured within the orifice of one of the chimneys, which was then broken off and recovered with the submersible. Both black and white "smoke" was observed to be emanating from the one chimney sampled. The high-temperature chimney extends directly from a field of broken lobate lavas which are located at a water depth of 1,550 meters, about 200 meters east of the caldera wall. The chimney makes one of the shallowest active high-temperature vents studied to date. The vent is surrounded by clumps of vestimentiferan worms and is located within an elongate field of red-colored iron smectite blankets and chimneys. The low-temperature field forms a ribbon 150 meters wide, extending for about 1,300 meters at the base of the wall. Chemical analyses of the hydrothermal deposits ranging from the polymetallic sulfides of the chimney to the outer zones of the low-temperature field show a range of elemental assemblages consistent with temperature zonation around the vent. Chemical zonation within the high-temperature

Jan 1, 1988

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

Jan 1, 1993

By Peter E. Halbach

The Central Indian Ridge (CIR), the boundary between the African and Indian plates, forms a SSE trending mid-oceanic accretionary system in the equatorial Indian Ocean (Fig. 1), extending to the northerly Carlsberg Ridge spreading center, and terminating at the Rodrigues Triple Junction (RTJ; 25°30'S, 70°06'E) by intersection with the Southwest Indian Ridge (SWIR) and the Southeast Indian Ridge (SEIR). Crustal divergence of the CIR proceeds at intermediate rates; a progressive increase of ocean floor accretion towards the south is documented: the present half spreading rate and ridge trend change from 1.80 cm/a and N142° at the equator to 2.73 cm/a and N152° north of the triple point. The topography of the central rift zone is rather smooth compared to slow spreading analogues such as the SWIR, but slightly more rugged than the SEIR. The rift valley is 500-800 m deep, 10-15 km wide and usually well defined. The inner floor, 2-4 km in width, is relatively flat along the axis and more variable in cross section, and lies at 2700-3200 m depth. Off set fracture zones striking generally N60° . in southern portions of the CIR and laterally displacing median valleys by as much as 8 km are often bent, uplifting crustal sequences up to several hundred meters. The length of individual spreading segments varies between a few and several tens of kilometers. The vertical displacement on normal faults are larger while lineaments are shorter than those of the faster spreading SEIR. The direction of lineaments measured on the southwestern and northeastern flanks of the southern CIR are N154° and

Jan 1, 1994

By Nobuyuki Okamoto, Bhaskar Rao

For a period of twenty years - from 1985 to 2005 - the Japan Oil, Gas and Metals National Corporation (JOGMEC) and Pacific Islands Applied Geoscience Commission (SOPAC) have jointly conducted surveys of deep-sea mineral resources in the EEZs of SOPAC’s twelve member countries. The overall Programme has obtained excellent results and has identified numerous sites with potential marine mineral resources of manganese nodules, cobalt-rich manganese crusts, and polymetalic massive sulphides. The survey cruises have identified numerous sites with potential marine mineral resources such as: manganese nodules in the Cook Islands; cobaltrich manganese crusts in the Marshall Islands, FSM, and Kiribati; and polymetalic massive sulphides in Fiji. Based on collected samples and acoustic data, inferred resources for manganese nodule, cobalt-rich manganese crusts, and polymetalic massive sulphides, have all been estimated to be about- 200 million tons in the central Cook waters- 200 million tons in the three seamount selected Marshall waters- and 500 thousands tons around the triple junction of the North Fiji Basin.

Oct 15, 2007

By Katherine H. Walton

The research affiliate projects of the Continental Shelf Division of the Marine Minerals Technology Center concentrate on the development of technologies and methodologies for the exploration 4 and assessment of nonfuel continental shelf mineral resources within the U.S. Exclusive Economic Zone. Three of the FY 1990-91 research grants are summarized below. Scientists at the Center for Applied Isotope Studies at the University of Georgia have developed ?An Advanced Design for a Seafloor Gamma Isotope Mapping System? for the rapid collection of data on seafloor sediments. This system is designed to detect gamma radiation emitted by naturally occurring radioactive elements found in marine sediments. This data can be used to study seafloor lithology and has direct application in marine mineral surveys. The purpose of this study has been to redesign and calibrate the system for marine mineral survey work. Recent modifications of the sled design, gamma radiation detector, and supporting software have resulted in considerable improvements in sensitivity, functional operation, and data acquisition.

Jan 1, 1991

By Geir Johnsen

Hyperspectral remote sensing has been used extensively on land to identify minerals for the mining industries. An underwater hyperspectral imager (UHI) has been developed at the Norwegian University of Science and Technology. It captures optical fingerprints within the spectral range of 400-700 nanometers, with 1 nm resolution. The UHI has been tested on nodules and SMS deposits in the laboratory and on the sea floor to establish if this technology can be used to identify marine mineral deposits, to determine type of deposit and distribution.

Jan 1, 2010

By Carl H. Hobbs

The marine mineral resources of the U.S. middle and south Atlantic shelf are little utilized. The largest resource, sand and gravel, is used for beach nourishment and protection and, to a much lesser degree, as construction aggregate. The potential for increased utilization is great. Submarine deposits of shell have been mined for lime and for use in the oyster industry. Although significant quantities of manganese nodules and crusts are present on the Blake Plateau, exploitation in the foreseeable future is unlikely. Similarly, major phosphorite deposits in North Carolina's inner shelf probably will remain unexploited as long as onshore deposits remain available. Placer deposits of heavy-mineral sands, especially the titanium minerals, offer the possibility of exploitation. This possibility might be enhanced by consideration of joint development of sand or aggregate with heavy minerals.

Jan 1, 1992

By Jan Magne Markussen

China, India and South Korea are three developing/newly industrialized countries that can show a very positive economic development in latter years. Moreover the three countries also feature amongst the countries with the highest level of activity in deep seabed mining today. India was the first country to achieve Pioneer Investor status in accordance with the UN Convention on the Law of the Sea. The country has carried out comprehensive exploitation of nodule deposits in the Central Indian Basin. India has an active programme for development of mining technology and internationally, India is probably the leading nation today as far as processing technology is concerned. China for its part has established a central coordination unit for its deep seabed involvement and its exploration and technology development is already well underway. South Korea has applied for Pioneer Investor status and much indicates that it will be allocated its own minesite in the autumn of 1994. The three countries are in mutual contact in the area of the Law of the Sea. Korea contacted both China and India when drawing up its application for pioneer investor status and allocation of minesite. However, no cooperation exists between the three regarding for example technology development, economic analysis or in studies of the environmental consequences. The main purpose of this paper is to focus on why and how the three countries would be well advised to cooperate in the above areas. Economic, technological and organizational aspects all point in that direction.

Jan 1, 1994

By Cheng Xiangzhou

The China Ocean Mineral Resources Research and Development Association (COMRA) conducted a topographic survey in its deep seabed claim area with the SeaBeam system in 19475. After analyzing the data, it was determined that there is a group of living things several hundreds of meters in depth that significantly affect the sound waves in the frequency range of interest. We will attempt to investigate more about such influences. Physical model testing is an important means for studying the theory, and for development of the technology for geophysical prospecting. Because the manganese nodules are distributed over the sea floor in irregular patterns, it is hoped that study of the acoustic properties of manganese nodules by means of physical model testing can improve interpretation of the data of the multi-beam system and the SeaBeam system. This will provide a more reliable basis for delimiting the mineral site and evaluating the reserves in the Pioneer area of China.

Jan 1, 1996

By John Noakes

Marine scientists at the University of Georgia, have in the past few years, designed, developed and refined two geochemical survelliance systems for the exploration of hard mineral resources on the seafloor. The one first developed is an underwater sled which contains a nuclear radiation detector for measuring naturally occurring gamma radiation that is associated either with marine phosphorites containing uranium and its decay daughters or thorium decay products that are indicative of monzanite. The latter can, in most instances, be used as a pathfinder mineral for placer deposits that may contain other heavy minerals of interest such as rutile, ilmenite, chromite, gold, etc. This sled is operational in continental shelf depths. The second system is capable of more definitive measurements in the form of direct elemental analyses of the silt and clay fractions within the surficial sediments. It consists of a towed sled containing a submersible pump which, upon agitating the sediments, transfers the finer fraction up a hose to a shipboard centrifugal cone then to an automated sample processor. The resultant samples are rendered into sediment wafers, suitable for non-destructive XRF analysis. The system is capable of shipboard analysis for specific elements within minutes after sampling, allowing a cursory look upon which an exploration grid can be formulated while on site. A much wider spectrum of up to 40 elements can be evaluated when the wafers are returned to the land based laboratory.

Jan 1, 2011

By Sally Philpot, Siân E. Boyd, Hubert L. Rees, Emma Bee, Carla Houghton, Ceri James, Silvana N. R. Birchenough, S. Limpenny David, A. Coggan1 Roger, Koen Vanstaen

Every year approximately 22 million tonnes of marine sand and gravel are dredged form British waters. The eastern English Channel (EEC) contains substantial reserves, a proportion of which have been identified by the aggregates industry for potential future exploitation. The main aim of this study is to produce broadscale marine habitat maps of the EEC area. The UK aggregates industry has formed a consortium of representatives (the eastern English Channel Association), and have sponsored an initial baseline survey and follow-up sampling programmes as part of a Regional Environmental Assessment (REA) covering a patchwork of aggregate prospecting areas. To complement this effort, a large-scale geophysical survey was conducted in 2005 to place the REA in a wider spatial context and, thereby, to help assess the environmental significance of any future impacts arising from commercial aggregate extraction over the broader region of the EEC.

Sep 24, 2006

By Subramanian Rajendran

Placer minerals are one of the rich natural resources readily made available primarily and broadly in the form of inland placers, beach placers and offshore placers. The exploitation of placer minerals goes back in the history for a period of time immemorial in the form of alluvial placer mining. In India only 35% of coast has been scanned for beach placer minerals. The buried inland placers and offshore placers have not been given due attention. Integrated management and sustainable development of coastal and Open Ocean including the EEZ are of great importance to us. Judicious exploitation of non-renewable mineral resources plays an increasingly important role with regard to future economic and social development. This calls for newer techniques for exploring and analyzing more the seafloor. Though India could remain in the placer mining for the last four decades through the establishment of the Indian Rare Earth in both east and west coasts, the lack of necessary dynamism to expand such industry and catch the world market points out a significant setback. It is highly essential to establish the major trends of paleo-beaches, since some of them are definite to contain highly rich heavy mineral placers comparable to the one being mined by beach scraping. Placer deposits of heavy minerals occur in discontinuous patches on the beaches along the West Coast of India. In recent years the National Institute of Oceanography, India and the Geological Survey of India attempted to invest on nearshore placer exploration by applying the integrated survey techniques.

Jan 1, 2001

By V. Zaykov

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

Jan 1, 1993

By Øystein Sture, Kurt Aasly, Ben Snook, Sigurd A. Sørum

INTRODUCTION Efficient exploration methodologies for base metal deposits have huge benefits for future deep sea mining endeavours, and underwater hyperspectral imaging (UHI) has been variably demonstrated to have applications in the identification and characterisation of mineralisation on the seafloor for both nodules and seafloor massive sulphides (SMS) (Dumke et al., 2018 and 2017 respectively). Due to growing resource requirements (Singer, 2017), SMS deposits are considered to be increasingly significant sources of copper and zinc, as well as silver and gold. This style of mineralisation is currently occurring at active hydrothermal vents (black and white smokers) but now-inactive sites also have the potential to be large mineral deposits. As such, the development of novel methodologies to detect both on-going and extinct mineralisations are of high importance. Geological setting During the MarMine cruise (Ludvigsen et al., 2016), non-mineralised host rock, low grade ore and high grade ore grab samples (Snook et al., 2018) was collected by ROV from the Loki’s Castle deposit (Pedersen et al., 2010), located on the Mohn’s/Knipovich junction on the ultra-slow spreading Arctic Mid-Ocean Ridge (AMOR), at a depth of approximately 2300 m. This material has been characterised as part of the MarMine project (e.g. Snook et al., 2017), and, by imaging compositionally constrained material, the measured hyperspectral responses can be used to generate a library for identification of deposits on the ocean floor. UHI technology Remote sensing with hyperspectral and multispectral technologies has seen wide use in prospecting for ores and hydrocarbons on land (Van der Meer et al., 2012). Iron oxides and sulphides have low blue reflectance and high red reflectance in the visible spectrum. The ratio between these two pairs has been used in exploration for terrestrial deposits of hydrothermal origin (Sabins, 1999). This discrimination typically also includes wavelengths exceeding the visible spectrum (1.5µm – 2.5µm). These wavelengths are typically not utilised underwater because infrared wavelengths and higher are rapidly attenuated in water. However, discrimination based on the full shape of the spectral response in the visible light (350nm – 800nm) may still be possible (Bolin and Moon, 2003). Resolving the endmembers from the spectral responses requires prior knowledge about the optical properties of the materials, i.e. their reflectance. These reflectances can be obtained in a controlled environment, where the spectra of the lamps, wavelength- dependent attenuation in water and scattering of light can be accounted for (Johnsen, 2013).

Jan 1, 2018

By S. Rajendran

Gas Hydrates (Methane Hydrates) are solid, ice-like substances composed of water and natural gas. They occur naturally in areas of the world where methane and water combine at appropriate conditions of temperature and pressure and are found in ocean bottom sediments and in some permafrost areas. Besides temperature and pressure, factors like bathymetry, sediment thickness, sedimentation rates, and total organic carbon content (TOC) also control gas hydrate formation in the ocean basins. The stability of gas hydrates depends on the critical combination of high pressure and low temperature (0 - 17 bars, 0 - 25°C), which in turn is dependent on the mix of gases from which the mineral is formed. As the critical parameters can be altered by deposition, erosion, slumping, formation or melting of ice cover, rise and fall of sea level, and sudden temperature changes induced by tectonic activities, current flow, or volcanisms, the gas hydrates tend to be very unstable. The Indian offshore is promising for the occurrence of gas hydrates in a total of about 80,000 km2 area in the bathymetry range of 700 to 3000 m as reported in earlier surveys. A gas hydrate stability zone thickness map was prepared using bathymetry and sea bottom temperatures along the continental margins of India. This map is expected to provide the depth window while searching for Bottom Simulating Reflectors (BSR). The study indicates that a minimum water depth of 750 m is required for the formation of gas hydrates, above which the chances for gas hydrate occurrence appear minimal despite other favorable conditions like organic-rich sediments, etc. Single-channel seismic analog records (Gupta et al., 1998) indicate that the Western Continental Margin of India (WCMI) offers a greater promise for gas hydrate occurrences, particularly with regard to the number of BSRs traced on the analog records as compared to earlier surveys.

Jan 1, 2005

By S. Naidu, J. Kelley, Roger Amato

The Alaskan Continental Shelf covers 76 % of the total shelf area of the United States. There are a lot of potential gravel deposits in the Alaskan offshore region. The gravel resources are currently not feasible for mining for the following reasons (U.S Congress, 1987): 1. Much of the glacial gravel is poorly sorted. 2. Gravel deposits are overlain by sandy and muddy layers. With the sea level expected to rise 70 cm in the next 100 years (Intergovernmental Panel on Climate Change, IPCC, 2001; Day, 2004), erosion of coastlines will be a major problem not only in Alaska but worldwide. Hence beach nourishment projects designed to minimize erosion will require large volumes of sand and gravel. Offshore areas will become a logical source for the fill material because of their proximity and ready availability. It is likely that future supply of coarse aggregate in Alaska may involve exploitation of marine deposits. The Chukchi Sea is a potentially favorable region for this type of mining because of extensive deposits of paleo beach and other relict gravel found in the near shore region (Stauffer, 1987). However a systematic analysis of potential gravel resource has not yet been conducted and it is the purpose of this research to estimate the size, extent and variability of gravel material that may be available in the continental shelf, offshore Kivalina.

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