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By Timothy F. McConachy

Between April 2000 and April 2002, the Commonwealth Scientific and Industrial Research Organization (CSIRO) Division of Exploration and Mining has led 6 research expeditions totalling 160 days ship time in waters of Papua New Guinea, Vanuatu, Solomon Islands, Indonesia and Australia. Five expeditions were undertaken aboard the Australian research vessel Franklin following successful competitive research proposals, and the sixth used the Indonesian vessel Baruna Jaya VIII (see Table 1). In addition, two CSIRO participants joined JOIDES Resolution for the Ocean Drilling Program Leg 193 in the Manus Basin of PNG. The major scientific objective underpinning these expeditions was to locate and study present-day seafloor and sub-seafloor hydrothermal ore-forming activity in order to develop improved methods of exploring for ancient mineral deposits on land that originally formed by similar processes. The research has been supported financially by a number of Australian-based mineral companies, by Australian international aid agencies, and by appropriation funds from CSIRO, and was conducted in collaboration with researchers from Australia, Indonesia, Portugal, New Zealand, United States of America, South Korea, and the host nations. Building upon earlier successes in the 1986-1997 PACLARK-PACMANUS programs in the Woodlark and Manus Basins of PNG, we have sought to examine a wider range of geological settings in which ancient orebodies are inferred to have formed, including both volcanic and sediment-hosted environments. We have now visited volcanic arcs, fore-arc and triple-junction related submarine volcanoes, and back arc basins associated with convergent plate margins in the SW Pacific and SE Asia, as well as conceptual Mississippi-Valley-type targets associated with warm seeps at passive margins in the Great Australian Bight (see Figure 1). Surveys ranged from northern Sulawesi via far western Bismarck volcanic arc near PNG-Indonesia border, through the eastern Manus Basin and the Tabar-Lihir-Tanga-Feni chain in PNG, the western Solomon Islands festoon, the San Cristobal arc, parts of the Vitiaz arc, to the northern and southern New Hebrides arc in the Solomons and Vanuatu.

Jan 1, 2002

By Ivar Eskerud Smith, Ole Jørgen Nydal, Niranjan Reddy Challabotla, Svein Sævik

INTRODUCTION Airlift pumping, utilize compressed air that is injected at the bottom of a vertical pipe submerged in the water, reduces the mixture density inside the pipe and lifts the liquid or mixture of liquid and solids. This type of pumping technology, which is simple and without moving parts submerged in water, which provides several advantages compared to the mechanical pumping. Airlift is used in various difficult pumping applications such as transport of fluids corrosive to metals, explosives, nuclear and toxic materials in chemical industries, diamond mining and coal transport. Application of airlift to deep sea mining conditions was investigated by extensive laboratory experiments [1], theoretical analysis [2], and limited proof of concept field studies [3] starting in 1970’s with the discovery of huge amounts of manganese nodules discovered on the seabed at a depth of ranging from 4000 to 6000 m . Even after extensive investigations over the last five decades, there exists no commercial application of airlift technology for lifting of minerals. The major problems with the application airlift for deep ocean mining was (a) lack of control over the expansion of the injected gas, which increases the velocity in upper part of the riser pipe (b) lower efficiency compared to mechanical pumping [3]. Different flow regimes are encountered in airlift pumping: bubble, slug, churn and annular flow. Annular flow regime is the least efficient in lifting of particles and churn flow has better efficiency [3].

Jan 1, 2018

By Rolf B. Pedersen, Filipa Marques

The extension of the Mid-Atlantic Ridge north of Iceland has collectively been referred to as the Arctic Mid-Ocean Ridges (AMOR). The AMOR extends from the northern shelf of Iceland, to the Siberian shelf in the Laptev Sea, passing en route through the Norwegian- Greenland Sea, the narrow gateway of the Fram Strait, and across the Eurasia Basin. The AMOR is 4000 km long and is divided into six super segments: 1) the Kolbeinsey Ridge, 2) the Mohns Ridge, 3) the Knipovich Ridge, 4) the Molloy Ridge, 5) the Lena Trough, and 6) the Gakkel Ridge. After continental rifting at 60-50 million years ago, around 2.5 million km2 of oceanic seafloor has formed by seafloor spreading - resulting in the formation of the Norwegian- Greenland Sea and the Eurasian Basin. This northernmost part of the global ridge system is anomalous in several ways: The seafloor spreading takes place at an ultraslow rate (less than 2 cm/y) with spreading rates decreasing northward to around 1 cm/y at the Gakkel Ridge - which is the most slow-spreading ridge on Earth. As a result, the volcanic activity along the northern part of the AMOR is low, the oceanic crust is unusually thin (around 3,5 km at the Knipovich Ridge, Kandilarov et al.2010), and the rift valley is deep (average water depth > 3 km). In the southern part of the AMOR, the ridge system is affected by the Icelandic plume and a hot spot below Jan Mayen. The ridge-plume interaction results in higher volcanic productivity, unusually thick oceanic crust (9-11 km, Kandilarov et al. 2012) and shallow ridge segments (1500-100 m). The AMOR also display contrasting spreading regimes, whereas some super segments are dominated by orthogonal spreading (Kolbeinsey and Gakkel Ridge) others are characterized by highly oblique spreading (Mohns and Knipovich ridges). Some ridge segment displays asymmetric spreading, like the Mohns Ridge where core complexes preferentially form along the northwestern flank. Together these variations in ridge characteristics results in large diversity of hydrothermal systems and associated mineral deposits.

Jan 1, 2018

By Isobel Yeo, Florent Szitkar, Sven Petersen, Sebastian Graber, Meike Klischies

Technological advances and the shift towards green energies in the last decades have led to a substantial increase in the demand for metal resources. With rising political tension, and quasi-monopolistic production of some key metals, a secured supply chain cannot be guaranteed [1]. Therefore, the focus of the international research community and mining companies has expanded to the seafloor, looking for additional resources. The seafloor may have the potential to contribute significantly to a secure metal supply in the future. However, we have only investigated a fraction of our oceans in sufficient detail to assess the global resource potential. A detailed exploration of the vast seafloor is currently economically not feasible, due to its extremely time-consuming and costly nature. Seafloor massive sulfides generally form along the active plate boundaries and at active volcanoes in arc settings. However, the resources are not evenly distributed on the seafloor. Large deposits tend to be more common along slow-spreading and ultra-slow- spreading ridges that make up the majority of the global mid-ocean ridge system [2]. Therefore, it is important to establish geological models and exploration criteria in order to narrow down the permissive areas, which are likely to accommodate economically interesting deposits. Based on a detailed study of the TAG hydrothermal field in the central Atlantic Ocean, hosting a large active mound as well as several inactive mounds, we develop exploration methods and criteria to define areas of potential massive sulfide occurrences along slow-spreading sections.

Jan 1, 2018

By G. B. Carpenter

The United Nations Law of the Sea (LOS) Convention includes provisions (Article 76) for establishing the outer limits of a coastal State's continental shelf and for denoting the seaward extent of sovereign rights over natural resources. Determination of a coastal State's continental margin, according to Article 76, must consider eight factors: 1. The territorial sea baseline 2. The 2,500-meter isobath 3. The foot of the continental slope 4. A line 200 nautical miles seaward of the territorial sea baseline 5. A line seaward of the foot of the continental slope connecting the points where sediment thickness divided by distance to the foot of the slope equals .01 6. A line 60 nautical miles seaward of the foot of the continental slope 7. A line 100 nautical miles seaward of the 2,500-meter isobath 8. A line 350 nautical miles seaward of the territorial sea baseline Figure 1 shows the preliminary limits for each of the Article 76-based definitions for a portion of the U.S. Atlantic continental shelf. The additional areas gained beyond the 200- nautical mile Exclusive Economic Zone (EEZ) are highlighted. The first three factors are baselines from which the distance provisions of Article 76 are measured. Factors 4-8 are distance- from-baseline provisions for establishing the continental shelf limits. Factor 5, also known as the Depth of Sediment Limit or "Irish Formula", was calculated using sediment thickness data from seismic linesand isopach maps. All other factors were determined from digital hydrographic data. The Depth of Sediment Limit is the most advantageous method for the area shown in Figure 1. It is especially useful for introverted coastlines such as the Georgia Embayment and New York Bight areas. The 200-mile line is advantageous for protruding coasts such as those off major capes, e.g., Cape Hatteras. The 2,500-meter isobath plus 100-mile line gains

Jan 1, 1995

By Tetsuo Yamazaki

Seafloor massive sulfides (SMS) in the western Pacific have received much attention as resources for gold, silver, copper, zinc, and lead (Lenoble, 2000). Since the end of the 1980s, SMS have been found in the back-arc basin and on oceanic island-arc areas. The typical representatives found are in the Okinawa Trough and on the Izu-Ogasawara Arc near Japan (Halbach et al., 1989; Iizasa et al., 1999), in the Lau Basin and the North Fiji Basin near Fiji (Fouquet et al., 1991; Bendel et al., 1993), and in the East Manus Basin near Papua New Guinea (PNG) (Kia and Lasark, 1999). The higher gold, silver, and copper contents in one of the areas increased the chance for profitable mining operation, which was considered by a private company (Malnic, 2001). The company gathered investment money and announced to start the commercial mining from 2010 (www.nautilusminerals.com). On the basis of geological information of the Sunrise Deposit of the Myojin Knoll on the Izu-Ogasawara Arc (Iizasa et al., 1999) and geotechnical characteristics of SMS (Yamazaki and Park, 2003), some preliminary economic validation analyses of the SMS mining in small production scale were reported by one of the authors (Yamazaki et al., 2003; Yamazaki and Park, 2005; Yamazaki, 2007). The results showed high profitability of the SMS mining.

Jan 1, 2011

By Tetsuo Yamazaki

Manganese nodules on deep ocean floors have continuously received attention as potential sources for strategic metals such as Co, Ni, Cu, and Mn, due to their vast distribution and relatively higher metal concentrations (Mero, 1965; Cronan, 1980). Several registered Pioneer Investors have already identified promising sites in deep-sea regions for manganese nodule mining (ISA, 1998), and appropriate mining technologies have been developed during the last thirty years by the international consortium and several nations (Welling, 1981; Kaufman et al., 1985; Bath, 1989; Charles et al., 1990; Yang and Wang, 1997; Yamada and Yamazaki, 1998; Hong and Kim, 1999; Muthunayagam and Das, 1999). The mining feasibility for manganese nodules, including an economic evaluation, has been examined in detail by some researchers (Andrews et al., 1983; Hillman and Gosling, 1985; Charles et al., 1990; Soreide et al., 2001).

Jan 1, 2011

By Andrea Koschinsky

Ferromanganese crusts have traditionally been considered a potential ore for Co, whereas ferromanganese nodules have typically been considered a potential ore for Ni and Cu. However, both nodules and crusts sequester high concentrations of many metals (Table 1) from sediment pore waters and seawater, many of which are essential for high-tech applications. The resource potential of these rare and valuable metals is poorly known and they are the subject of considerable current research. The need for adequate and dependable supplies of these metals is essential for the development of new technologies. The rare-earth elements have recently received much attention in the scientific and popular press because of their use in so many high-tech applications and because more than 95% of the production comes from China (e.g., Service 2010); consequently, there is concern about the possibility of a significant decrease or even curtailment in exports from China. The lack of a primary source and the inadequate supply of Te have prohibited the development of a Cd-Te photovoltaic solar-cell industry (Hein et al. 2010). Inadequate supplies of many of the elements listed in Table 1 are limiting the development of key high-tech industries, forcing the use of alternative metals that [ ] may result in less efficiency or less favorable properties for a product. The rare-earth elements, Te, and other elements listed in Table 1 occur in high abundances in marine hydrogenetic and diagenetic ferromanganese deposits. Here, we look at the mechanisms by which these rare and valuable metals are incorporated into different genetic types of marine ferromanganese deposits.

Jan 1, 2010

By Andrew G. Hudson

The long-term economics of each of the four principal metals in marine manganese nodules (copper, nickel, cobalt and manganese) was evaluated to determine the anticipated viability of a nodule mining venture based on existing studies of the potential profitability of a nodule project. This included assessments of the lifetimes of land-based reserves, and examination and econometric modelling of the economic variables thought to affect nodule metal prices and demand. These analyses demonstrated that a) land-based reserves of the nodule metals were likely to last well into the future (100 400 years); b) average nodule metal paces were likely to stay a low levels for the foreseeable future; and c) the expected revenue stream from a twenty- ear nodule mining venture was substantially (42%) below that required to attract the necessary investment capital for such a high risk venture.

Jan 1, 1996

By Se-Won Chang

This is a part of the joint KIGAM-GNS-NIWA 3-year study of ferromanganese nodules on the Campbell Drift, east of Campbell Plateau to determine age distribution, growth rates and geochemical evolution in relation to geographic setting. During the research voyage SAA3 by R/V Tangaroa (TAN 9909) in July-August 1999, seafloor sampling and camera towing were conducted along the two transects across the known flow path of the Deep Western Boundary Current (DWBC) perpendicular to the lowermost margin of the Campbell Plateau and Bollons Seamount. The four major nodule facies, SHH (slope hydrogenetic nodules with high density), AHH (abyssal hydrogenetic nodules with high density), ADH (abyssal diagenetic nodules with high density), and ADL (abyssal diagenetic nodules with low density) were identified. Two additional minor nodule facies, SIB (slope irregular nodules with ice-rafted boulders) and SHB (slope hydrogenetic nodules with boulders and crust), of localized distributions are also identified.

Jan 1, 2003

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 Carsten Rühlemann

Between 2008 and 2013, the German Federal Institute for Geosciences and Natural Resources (BGR) carried out five exploration cruises to the German license area in the eastern Pacific Nodule Belt. The first two expeditions were mainly dedicated to multibeam mapping to obtain an overview of the seafloor topography and acoustic backscatter strength. These data were used to identify ten to fourteen prospective nodule fields for potential future mining, which together cover about 16% of the total license area of 75,000 km2. During the last three cruises, three of these potential mining areas were explored in detail. For this purpose, the BGR developed a suite of exploration methods to map nodule size distributions and nodule abundances. These methods include acoustic surveys with vessel-based multibeam systems as well as near-bottom video mapping complemented by in situ sampling. The economically most valuable field has a size of ca. 2,000 km2, of which 34% is covered by medium to large nodules (> 4 cm long axis of nodules) with an average abundance of 22.4 kg/m2 and 44% is covered by small nodules (< 4 cm) with a mean abundance of 17.5 kg/m2. The total mass of nodules in this field comprises more than 30 million tons wet weight and could sustain deep-sea mining for at least 10 years.

Sep 14, 2011

By Derek V. Ellis

A stepwise implementation of seven criteria for screening the physical, chemical and environmental suitability of submarine tailing disposal (STD) at coastal mines is presented. It is expected that similar criteria would be relevant to future deepwater mining. A reconnaissance level study of four preliminary criteria: mine location; coastal bathymetry; feasible outfall locations; and potential for chemical contamination can support or eliminate the prospects for STD. If supportive, detailed, and far more time-consuming hence costly surveys of: environmental background information including oceanography and waste discharge characteristics; projected impacts on other resource uses plus regulatory and community concerns will be essential for environmental protection and to secure the necessary approvals. This review of STD systems on which the proposed screening criteria were based was undertaken by a Cooperative Agreement of the U.S. Bureau of Mines, Alaska Field Operations Center with the University of British Columbia.

Jan 1, 1994

By Johnson R. Cann

Ocean floor sulfide deposits are now known from many parts of the world mid-ocean ridge system and from some seamounts. Clearly they can be expected to occur commonly on the ocean floor. However, only two or three of the known deposits appear to approach the million-ton size, and in none of the deposits has the grade been well-defined. Can knowledge of the processes that happen within the hydrothermal plumbing below deposits help define the conditions under which large, high-grade deposits form? Here I review present knowledge of ocean-floor hydrothermal processes to attempt a first answer to this question. There are three sources of information about these processes. The solutions emerging from active systems must be compatible with patterns of alteration that underlie the volcanogenic sulfide deposits of ophiolite complexes, which are slices of ocean crust thrust onto land. Both of these types of evidence can be linked by computer modelling of the exchange of heat and metals between rocks and flowing water.

Jan 1, 1988

By K. Vanstaen, K. M. Cooper, S. Ware, S. L. Boyd

Remediation and restoration of offshore marine habitats is a relatively new concept with attempts in European regions largely being instigated by requirements of various strategic directives including Article 2 of the Habitats Directive (1992), the EC Water Framework Directive (2000, Article 2 of the OSPAR Convention (1992) and the developing European Marine Strategy Directive. A field experiment to establish the practicality of various options for rehabilitating the seabed on the cessation of dredging has been successfully set-up. The purpose of this experiment is to investigate the practicality and effectiveness of gravel seeding as a potential restorative method which could be applied at marine aggregate extraction sites following cessation of dredging. Zone 2, within Area 408 (offshore Humber) was chosen as the experimental site as there is some evidence for persistence of sand which may have resulted from screening operations at this site.

Aug 24, 2006

By Natalia Konstantinova, Kira Mizell, James R. Hein, Georgy Cherkashov

"Ferromanganese crusts and nodules from the Amerasian basin of the Arctic Ocean are characterized by a unique composition compared to crusts formed elsewhere in the global ocean (Konstantinova et al., 2017; Hein et al., 2017). One of the most significant differences from global ocean crusts is the high detrital mineral content; mass balance calculations show that it may be as high as 35% in some samples (Hein et al., 2017).These Arctic Ocean Fe-Mn crusts also typically have three distinct megascopic layers, except for thin crusts; less commonly, four layers are noted for thick crusts. The age of initiation of Fe-Mn crust growth in the Amerasia Basin varies from 14.8 Myr to 0.7 Myr ago based on the Manheim and Lane-Bostwick (1988) Co chronometer, Be isotopes, and Th excess methods (Dausmann et al., 2015; Konstantinova et al., 2017; Hein et al., 2017).Samples and MethodsFourteen Fe-Mn crust samples recovered on Russian and U.S. research cruises were chosen for analyses based on their morphology, composition, water depth, genetic type, and location in Amerasia Basin. Seven samples from four distant dredge sites along Mendeleev Ridge and seven samples from four locations on the Chukchi Borderland are included (Fig. 1). Dredge site water depths vary from 3850 to 2100 m with the deepest samples from the Chukchi Borderland. Many of the selected samples were described in previous publications (Konstantinova et al., 2017; Hein et al., 2017)."

Jan 1, 2017

By K. Vanstaen, K. M. Cooper, S. Ware, S. L. Boyd

Remediation and restoration of offshore marine habitats is a relatively new concept with attempts in European regions largely being instigated by requirements of various strategic directives including Article 2 of the Habitats Directive (1992), the EC Water Framework Directive (2000, Article 2 of the OSPAR Convention (1992) and the developing European Marine Strategy Directive. A field experiment to establish the practicality of various options for rehabilitating the seabed on the cessation of dredging has been successfully set up. The purpose of this experiment is to investigate the practicality and effectiveness of gravel seeding as a potential restorative method that can be applied at marine aggregate extraction sites following cessation of dredging. Zone 2, within Area 408 (offshore Humber) was chosen as the experimental site as there is some evidence for persistence of sand which may have resulted from screening operations at this site.

By Darryl Thorburn

The Cook Islands are 15 islands located in the Southwest Pacific (between 8-23°S latitude and 156-167°W longitude). The total land area is about 200 km2. However, because its islands are widely scattered, the EEZ of the Cooks encompass an area about 2 million km2. The Cook Islands government exercises sovereignty and jurisdiction over its EEZ according to international law and convention as a member state under UNCLOS1. Accordingly, the Cook Islands government exercises full control over resources in its EEZ, including minerals on the seabed. Decision making on allocating licences for exploration and ultimate mineral recovery is by the Cook Islands government and will be set out in relevant statutes. Seabed minerals investigations within the EEZ of the Cook Islands and adjacent waters were first carried out by, USSR, US, and New Zealand research vessels in the late 1960 early 1970?s and indicated the presence of high concentrations of manganese nodules. This early work was followed by a number of Government funded surveys in and adjacent to the Cook Islands EEZ These surveys have identified a world class resource of manganese nodules within the Cook Islands EEZ (CI EEZ), containing significant

Sep 14, 2011

By M. F. Dibble

The technology available for mining of underwater mineral resources such as placers and phosphorite, typically occurring with variable amounts of overburden, has remained largely unchanged for decades. The traditional bucket ladder dredge with maximum digging depth of 48 m and monthly capacities about 500,000 m3 still reins as the only heavy duty mining system capable of working the tough materials characteristic of heavy metal placers. Attempts at adapting the bucket wheel cutter-suction dredge to these severe conditions have not yet been successful except in moving small volumes from shallow depths. High capital cost (20-30 million U.S. dollars), high cost of overburden removable, and turbidity generation for the bucket ladder are often significant negative factors in mining operations where this system remains the only viable alternative. The Japanese continue to advance the technology of their submersible dredge pump system powered by specially adapted, direct drive electric motors. Present systems are designed primarily for working surficial deposits of aggregate to depths as great as 90 meters, the pump suspended by cable from a surface vessel with an eductor pipe leading from the pump to the vessel. Such a system may prove adaptable to a variety of surficial deposits including phosphorite, shell and heavy minerals in addition to aggregate. However promising for the exploitation of surficial deposits, little advantage can be expected for the deeper buried and more difficult deposits.

Jan 1, 1986

By Cornel E. J. de Ronde, Alexander Malahoff

Six active Kermadec arc submarine volcanoes, located between 34°S and 36°30&apos;S were mapped and sampled between April and July 2005, using submersibles Pisces V and Pisces IV aboard the mothership R/V Ka&apos;imikai-o-Kanaloa. The purpose was to study the relationship between hydrothermal activity, formation of hydrothermal mineral deposits, structure of the volcanoes, and the biodiversity of life associated with the hydrothermal vents. Of the volcanoes examined, all showed evidence of hydrothermal activity, including metal-rich plumes and helium anomalies. Only two of the volcanoes, namely Brothers and Clark, showed chimneys and surficial polymetallic sulfide deposition. Hydrothermal venting at a water depth of approximately 1,650 meters near the base of the northwest caldera wall of Brothers volcano has produced a field of chimneys, up to seven meters high and discharging black smoker venting. Temperatures up to 300°C were measured from the active vents. Clark volcano has a double cone summit at a water depth of 875 meters. The shallowest cone has a near-summit hydrothermal vent field with five-meter tall venting chimneys with smaller structures around the periphery. Water temperatures of 200°C were recorded for these chimneys.