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By Jonguk Kim

The North Fiji Basin (NFB) is a mature intraoceanic back arc basin with an age of ~12 Ma. Recent volcanism and spreading activity are focused along the Central Spreading Ridge (CSR), A ridge segment more than 800 km long, composed of four main segments, the N160°, N15°, north-south (N-S), and southernmost segments from north to south. The dominant volcanic rock in the entire central spreading ridge is normal mid-ocean ridge basalt (N-MORB), very similar to those emplaced along mid-oceanic ridges. Conversely, influence of an oceanic island basalt (OIB) source increases northward from 18°20'S. Several basalts which show a significant subduction-related component are also observed in the southern part of the NFB. Hydrothermal activity along the spreading centers of the North Fiji Basin was investigated by several previous works, especially by the STARMER project in 1989 and 1991. Both extinct and active hydrothermal vents are found on the N15° and N-S segments. In contrast, only traces of hydrothermal activity have been found on the N160° segment. Although high temperature activity and related massive sulfide deposit on the N15° segment was further investigated by several follow-up studies, no systematic survey for other hydrothermal sites was conducted after their discovery. In 2012 and 2013, KIOST performed two hydrothermal expeditions aboard the R/V Onnuri in the three targeted areas of hydrothermal activity along the CSR of North Fiji Basin. All targeted areas include sites for hydrothermal activity reported in previous works. Occurrence and distribution of hydrothermal plume were investigated by combined

Sep 14, 2011

By Andrea Koschinsky

Numerous hydrothermal vents occur along the Earth?s oceanic spreading axes documenting the reaction of seawater with hot magmatic rocks. The circulation of seawater through the oceanic crust, the interaction with hot rocks in the crust, and the subsequent discharge of hot metal- and gas-rich fluids into the ocean have significant implications for the cycling of material and energy on Earth. Until recently, hydrothermal activity was unknown from the Mid-Atlantic Ridge (MAR) south of the Equator where the MAR is offset by about 1000 km at the St. Paul?s and Romanche fracture zones. During a British cruise in February/March 2005, the first active hydrothermal vent field was discovered on the southern MAR at 5°S. During our follow-up cruise M64/1 in April 2005, the first samples from this vent field were recovered with the ROV QUEST (Univ. Bremen) and analyzed onboard. The high-temperature vent field is situated in a water depth of 2990 m along a line of collapse pits within a large basaltic sheet flow. A diffuse, low-temperature field occurs in a jumbled sheet flow few hundred meters to the east with warm water streaming out of cavities between lava blocks. Here we show for the first time that boiling fluids of ~400°C are emanating from sulfide-bearing vents at a depth of about 3000 m at a slow-spreading Mid-Atlantic Ridge segment. Although this segment is composed of thick basaltic crust, these fluids are dominated by hydrogen relative to methane. Whereas the active chimneys consist of pyrrhotite, chalcopyrite, and isocubanite, the mineral association hematite-magnetite-pyrite occurs in the inactive chimneys suggesting that the fluids became more reducing in present times. The high hydrogen contents and the high temperature of the fluids as well as the change to more reducing conditions are most likely related to a young volcanic eruption event some 300 m east of the hydrothermal field. The presence of hematite and magnetite may indicate that the upflow zone or even the reaction zone at 5°S used to be more oxidized then at other MOR sites, where the hydrothermal fluids are commonly buffered by the pyrite-pyrrhotite-magnetite (PPM) buffer. Consequently, high iron contents and high hydrogen/methane ratios occur in high temperature fluids from basaltic host rocks rather than being restricted to ultramafic host rocks. Faunal communities at the South Atlantic vents largely resemble those from the North Atlantic vents implying that the large Equatorial fracture zones do not inhibit or obstruct faunal exchange along the Mid-Atlantic Ridge.

Jan 1, 2005

By Alexander Malahoff

The new ship-submersible system with R/V Ka'imikai-o-Kanaloa as a mothership and the PISCES V as the submersible completed its first season of dives. The dives involved deployment of the PISCES V in the Hawaiian Islands between the months of July and October 1996. Submersible deployments up to depths of 2,000 meters in sea states up to a high three were made. The new hook and clasp deployment and retrieval connection for PISCES V to the telearm was shown to be an effective system for handling the PISCES V with the A-frame. The shipboard multibeam survey and seawater sampling capability proved to be especially effective in re-mapping the summit of the submarine volcano Loihi following a major volcano-tectonic event and for following the source and configuration of the new hydrothermal plume. Following the earthquake swarm of July 17 to August 18,1996, major changes in the geological setting of Loihi submarine volcano took place. Prior to the seismic event, the geology and structure of the summit of Loihi was represented by a platform-like area 8,100 meters long and 5,400 meters wide enclosed by the 1,200-meter depth contour. The summit was characterized by the presence of two prominent pit craters and eastern and western crater located at water depths of 1,100 and 1,370 meters, respectively. A hydrothermally active volcanic cone, named Pele's Vents, was located at a depth of 960 at the southern edge of the summit. The floor of the summit of Loihi was largely covered by prismatic talus, with interstitial hydrothermal clays. Pillow and tube lavas with volcanic cones 5 to 50 meters high were exposed along the axes of the southern and northern rift zones. The inner margin of the summit displayed fissures and normal faults with the downthrown component towards the center of the summit. The pre-earthquake structural data suggest a pre-caldera structural stage for Loihi. Maximum sustained hydrothermal activity observed on Loihi over the past 10 years existed at Pele's Vents with other sporadic venting occurs along the summit platform and along the south rift. Following the earthquake swarm, the hydrothermally saturated Pele's Vents cone gave way and slid into the inner pit crater. Subsequently, the observed above- bottom hydrothermal plume source deepened from 960 to 1,160 meters, possibly emanating from the same intrusive heat source as Pele's Vents. The observed inward collapse of the summit structures and subsequent opening of fissures gave rise to diffuse venting from the newly formed caldera-like depression with the bottom-hugging hydrothermal pool located at depth between 1,250 and 1,220 meters at the sites of the pit craters.

Jan 1, 1996

By Fredrik Søreide

The Norwegian EEZ contains large areas of interest for SMS exploration along the Mid- Atlantic Ridge, from Jan Mayen to Svalbard. At the same time Norwegian companies engaged in oil and gas activities are in the forefront of subsea development. This makes Norway ideally positioned to take a leading role within marine minerals research and commercialization. In the recent minerals strategy from the Norwegian Government marine minerals was pointed out as one of the strategic areas for the future. The Norwegian University of Science and Technology has established a research program in cooperation with Norwegian industry partners to determine the commercial potential of marine minerals in Norwegian EEZ. This presentation will give an overview of the status of marine minerals research and potential in Norway.

Sep 14, 2011

By Huaiyang Zhou

It has been long known that manganese nodules occur more or less in some part of marginal seas in West Pacific Ocean. On the other hand, it is difficult to understand their distribution and the genesis as those nodule samples were collected mostly by dredge from the deep basins generally has much higher sedimentation rate than the open ocean. For example, the sedimentation rate in the South China Sea is about three orders of magnitudes than that in region of the Clarion-Clipperton Fracture Zone. In June of 2013, a small seamount (named as Jiaolong Seamount), consisting of southern part and northern part with a distance of about 3 km each other, was visited by DSV Jiaolong/RV XiangYangHong 9. It is discovered that abundant manganese nodules exist only on the surface sediment in the southern part with a water depth of about 3800 m to 3300m, on the platforms nearby an obvious crater where volcanic rocks exposed on the wall. There are no any nodules be observed on the sediment in the northern part of the seamount (about 100 m deeper than the southern part) and surrounding deep basin (approximately 4000 m in water depth). It is speculated that a source of core for manganese nodule and a dynamic sedimentation environment, are two major governors for the growth and distribution of manganese nodule in the marginal seas.

Sep 14, 2011

By Teruyoshi Narita

In Japan, the Ministry of Economy, Trade and Industry (METI) commenced a research and development (R&D) project on seafloor massive sulphides (SMS) in Japan?s exclusive economic zone (EEZ) in the 2008 fiscal year. In this plan, the road map of Resource evaluation, environmental impact study, mining system technology and processing technology fields consisting of the first and second stage has been shown for the commercialization of SMS. Based on this road map, Japan Oil, Gas and Metals

Sep 14, 2011

By Campbell McKenzie

Substantial consideration has been given to the implications that the morphology of the Chatham Rise deposit will have on mining operations. The glacio-tectonic processes involved in the distribution of nodules on the rise has in several areas been quite significant. The recent cruises by Chatham Rock Phosphate Limited (CRPL) have collected data which has affirmed the assumptions previously made and catered for in historic resource estimations. The deformation and displacement of the phosphorite during glacial periods and the redistribution of the mobile sand during interglacial periods is interpreted to have produced a highly variable pattern of phosphorite concentration (kg phosphorite/m2) and coverage (% phosphorite/sample weight). The phosphorite resource probably has a significant spatial variability at a scale of tens of metres. Results of recent surveys show phosphorite-rich patches alternating with phosphorite-poor areas at distances of less than 20 m. The high spatial variability of the deposit has had a bearing on how historical information for the project has been regarded and integrated with the recent exploration approach and data collection process. This coupled with the proposed extraction tool has influenced the size, nature, extent and siting of the proposed mining blocks

Sep 14, 2011

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 Alister C. Skinner

The Marine Operations and Engineering section of the British Geological Survey based in Edinburgh, Scotland have, over the last 30 years, developed and operate a series of remotely operated, and powered, seabed coring systems. These systems were initially developed to provide a cost-effective solution to ground truth seismic reflection data for regional geological mapping, where the only solution that existed was conventional and expensive drill-ships. Since the early 1990?s these tools have been used for many other applications in industry and science. Currently the systems can operate in up to 2000 m water depth for 5m seabed penetration and up to 4500m water depth for a specialised oriented core drill which collects a scribed core to 0.8m below seabed. Scientific applications focus on determining the geology of an area and follows pre-determined geophysical interpretations. It usually also follows other coring attempts with non-powered coring equipment which is invariably unsuccessful if the strata is over-consolidated sediments or hard rock. Commercial applications include cable and pipeline route surveys, diamond, gold and base metal exploration, beach reclamation and aggregate materials evaluation. In many cases there is a blend of science and commercial investigation typified by coring in hydrothermal vent areas or carrying out geological coring in a frontier oilfield province. The versatility of the drills allows cost effective and rapid operations in remote and hostile areas where a rapid investigation may be the only one possible in a short weather window. The deepwater operational capability also allows science and commercial assay to be obtained ahead of potential exploitation and allows formulation of scientific theories or commercial project plans based on sound core data. Being mobile and compact these corers may be used from suitable (Dynamically Positioned or Anchored) vessels of convenience and thus provide a cost effective platform for sampling different types of seabed geology on an international basis.

Jan 1, 2004

By Cees van Rhee, Rudy Helmons

INTRODUCTION Seafloor Massive Sulphides are typically found near the oceanic ridges at larger water depths (>1km). The physical properties of SMS, as shown in table 1, are comparable to the properties of weak rock. One of the technical challenges to enable extraction from these locations is the cutting or excavation process. Experiments have shown that the energy needed to excavate the material may increase with water depth (Alvarez Grima et al. 2015). Besides that, it is demonstrated that rock that fails brittle in atmospheric conditions can fail more or less in a plastic fashion when present in a high pressure environment, as would be the case at large water depths. The goal of this research is to identify the physics of the cutting process and to develop this into a model in which the effect of hydrostatic and pore pressures is included. The cutting of rock is initiated by pressing a tool into the rock. As a result, at the tip of the tool a high compressive pressure occurs, which leads to the formation of a crushed zone. Depending on the shape of the tool and the cutting depth, shear failures might emanate from the crushed zone, which will eventually expand as tensile fractures that can reach to the free rock surface. Through this process intact rock will be disintegrated to a granular medium. For an overview of the process (figure 1). Additionally, the presence of water in the pores of and surrounding the rock influences the cutting process through drainage effects. The most relevant effects are weakening when compaction and strengthening when dilation occurs in shearing and tension. Deformation of the rock causes the pore volume to change, resulting in a under or over pressure. As a result, the pore fluid needs to flow. The magnitude of the potential under pressure is limited through cavitation of the pore fluid, limiting further reduction of the pore pressure (figure 2). The drainage effects cause the rock cutting process in a submerged environment to show a stronger dependency of both the hydrostatic pressure as well as the deformation rate (figure 3).

Jan 1, 2018

By Audrey Boissier, Marie-Anne Camon, Cecile Cathalot, Yves Fouquet, Laurent Bignon, Arnaud Agranier, Ewan Pelleter, Sylvain Bermell, Florian Besson

INTRODUCTION In October 2014, on behalf of the French government, Ifremer, along with the International Seabed Authority (ISA), signed a contract to start a detailed exploration program for seafloor massive sulfide (SMS) deposits in the work plan located on the slow spreading Mid-Atlantic ridge (MAR). The contract has a fifteen-year lifetime and the related exploration program must include the outline of SMS deposits and a resource assessment, as well as detailed environmental base line studies in the contract area. The exploration for SMS deposits generally includes detection of hydrothermal plume anomalies, acquisition of surface and near-bottom geophysical data, sampling operations from the research vessel (e.g. dredges, cores), and dive operations. The environmental studies include, among others, short and long-term oceanographic measurements, water column studies, biodiversity evaluation close and far from SMS deposits, characterization of natural hydrothermal plumes and related sedimentation. The HERMINE research cruise held from March 13th to April 28th 2018 (R/V Pourquoi Pas?) was the first cruise dedicated to exploration of active and inactive SMS and to the quantification of natural chemical input to the water column. The HERMINE cruise strategy was built up around three main objectives: (i) regional exploration including the detection of plume anomalies and the research of SMS deposits, (ii) local exploration of a SMS district and (iii) integrated study of a natural hydrothermal plume. This 3-in-1 cruise required us to optimize the switch between dives and surface operations. Day-time was devoted to dive operations whereas night-time was mostly dedicated to CTD/Rosette operations. The Nautile HOV (Human Occupied Vehicle) was well suited to the working time schedule of the cruise because it was time efficient in shorter (i.e. < 10h) dives due to fast descent and ascent speed, fast submerged forward speed, high maneuverability and the ability to carry heavy science payload as well as large volume of samples. Regional Exploration The first seventeen days of the HERMINE cruise were devoted to regional exploration, i.e. the detection of new plume anomalies and the research of new sulfide mineralization in the French work plan (10 000 km2; 6 clusters).

Jan 1, 2018

By Frans van Grunsven, Cees van Rhee, Geert Keetels

One of the obstacles during the initial phases of project development is the assessment of the environmental impact. Mining residue, consisting of fine seafloor sediments, are to be discharged subsea to mitigate the impact of these suspended particles. In order to test the effectiveness of discharging in proximity of the seabed, a numerical model is developed within the open source software package OpenFoam. Dedicated laboratory experiments for numerical model validation are discussed within this paper. INTRODUCTION Siltation is considered one of the major pressures on the environment for a seabed mining operation. Siltation is defined as the pollution of water by a high concentration of suspended sediments like clay or silt. This can be caused by two main activities during the mining process: the spill loss during the excavation and the return flow of undesired seafloor sediment after ore filtration on the ship. In a concentrated cloud, these fine particles form a so-called turbidity plume. Prediction of the size of these plumes and the created layer thickness of deposited sediment is a crucial part of the environmental impact assessment. The challenge in predicting the behaviour of these plumes is found in the wide range of scales involved in the process. At the point of origin, the turbidity plumes spread mainly under the influence of turbulent whirls created by an initial momentum and a buoyancy difference due to the presence of the suspended sediment particles. If carried by ambientcurrents, these plumes can spread for several kilometres before blending in the background.

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

By Peter E. Halbach, Andreas Jahn

"Co-rich ferromanganese crust deposits exist on slopes, summits and platforms of seamounts and guyots throughout the global oceans, where deep-sea currents have kept the seafloor structures more or less free of sediment for millions of years. They form by direct precipitation from cold seawater under more or less oxic conditions and consist of thin layers (2 up to 25 cm thick) covering hard substrate rocks in water depths of 800 to 5000m (Halbach and Marbler, 2009; Hein et al., 2000). Besides Mn these crusts contain interesting concentrations of minor elements (Co, Ni, Ti and Cu) and trace elements (Mo, W, Te, Ga, Pt and REEs), thus they represent significant metal deposits and promise potentially valuable additions to the world’s metal resources.The prospects for mining of this marine type of metal deposits largely depend on the grades and the scale of the potential ore resources. However, only a few percent of existing seamounts and guyots have been mapped and sampled in detail, most of them in the Pacific Ocean. Therefore, a model to estimate the geological resources based on the global seamount catalogue of Wessel (2001; revised: Wessel et al., 2009) and the empirical parameters which control the metal composition and distribution was developed."

Jan 1, 2017

By Tina Schneider

Scientists show that polymetallic nodules and massive sulfides from deep sea mining contain valuable metals. These metals have the potential to overcome future shortages of supply. Hence, companies, government agencies and industrial associations increasingly evaluate deep sea mining as a promising supplement of land mining. Technologies to extract, exploit, transport and smelt polymetallic nodules and massive sulfides industrially are still in conceptual stage and not sufficiently advanced for operation. According to the International Seabed Authority, large scale exploitation would require a successful pilot mining test in order to demonstrate e.g. the technological feasibility but also the conservation of environmental systems services. At the same time, NGO´s and a some scientists point out that large scale extraction of polymetallic nodules and massive sulfides could disturb the habitat of benthic organisms, with unknown long-term effects. Aside from the direct impacts of mining, indirect consequences about leakage are likely. In the oral presentation I will show how companies, government agencies, scientists and association/interest groups perceive and assess economical/technological, social and environmental risks and opportunities of deep sea mining. In order to analyze the perspectives of each stakeholder group on deep sea mining, we conducted 15 interviews with four stakeholder groups and a large scale survey (n = 500, return rate = 13 %) in Germany. We used the concept of sustainability with its economical/technological, ecological and social dimensions for the interpretation of the results. The empirical research shows the following core results:

Jan 1, 2018

By Andrea Koschinsky, Luise Heinrich, Stefan Gößling-Reisemann

"Germany, like several other countries, has entered a contract with the International Seabed Authority (ISA) to explore the prospects of commercial manganese nodule mining in the Clarion-Clipperton Zone (CCZ). Ensuring a maximally sustainable deep-sea mining operation requires a thorough understanding of the environmental impacts associated with every step of the mining process from the extraction of the nodules at the seafloor to the refinery on land. Against this background, the project presented here applies a combination of scenario-building and life cycle assessment (LCA) to assess and evaluate the sustainability performance of the individual process steps as well as the entire mining operation.Life cycle assessment (LCA) is a comprehensive methodological framework that allows the identification and quantification of impacts occurring during a products life-cycle, as well as the analysis and evaluation of their contribution to pre-defined impact categories, such as climate change, acidification and toxicity (Rebitzer et al., 2004). Until now, LCAs with a focus on raw material extraction have almost exclusively been applied to terrestrial processes. Noteworthy exceptions are offshore drilling, offshore wind farms and ocean fishing. Hence, the first part of the project is to investigate in how far LCA can be applied to deep-sea settings and if and in what way it could be adapted to be used in a deep-sea mining context."

Jan 1, 2017

By Andreas Kaede

INTRODUCTION Due both to the political history of UNCLOS and the sensitivity of the ocean floor and environment to man made impacts, both the Convention (including also the 1994 Amendment) and subsequent codification (such as the ISA draft code on Exploitation of Mineral Resources in the Area) put a focus on information about, and conveyance of, technology employed by interested deepsea mining companies, to inter alia the Authority and developing countries. In contrast, companies usually are (or by their nature should be) interested in safeguarding their technology and business secrets in order to secure unique selling propositions in a competitive environment. On the background of the meanwhile maturing regulatory régimes on deep sea mining, the presentation will look into some of the key regulatory provisions mirroring these apparently antagonistic interests, how the players involved could deal with them, and how they might in some cases be reconciled. Progress of Presentation The presentation will start by briefly examining some classical methods of protection of technology, such as patents, copyrights, and (not the least) secrecy. It will be found that some of the statutory means of protection due to their territorial character may face problems in being implemented in areas outside national jurisdiction, such as the Area, but that, thinking globally, they nevertheless retain much of their value for the purpose of protection. Depending on available presentation time, a model case may be used to illustrate the above – and also some of the following – findings.

Jan 1, 2018

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 Nobuyuki Okamoto

The 21-year long-term Japan-SOPAC Cooperative Deep-sea Mineral Resources Study Programme was completed in March 2006. The Programme, which commenced in 1985, has seen numerous marine research surveys being conducted within the Exclusive Economic Zones (EEZs) of 12 SOPAC member countries (Figure 1). The various research and government institutions that have been closely involved in this longstanding Programme include: the Japan International Cooperation Agency (JICA); Japan Oil, Gas and Metals National Corporation (JOGMEC) (formerly, the Metal Mining Agency of Japan, MMAJ) and relevant ministries of the participating Pacific Island governments.

Sep 24, 2006

By G. Cherkashov

The geodiversity of seafloor massive sulfides (SMS) deposits at the slow- and ultra-slow spreading ridges is of great variety (Fouquet et al., 2010). Tectonics and magmatism are the two principal factors which control SMS formation and localization. The geological setting of SMS deposits is determined by their position relative to the rift valley and by the types of rocks hosted (Table 1). Depending on the first parameter, SMS deposits could be localized at [ ] the axial volcanic ridge or at the flank of the rift valley. Basalts, deep-seated gabbro, and serpentinized peridotites are distinguished among the hosted rocks. The outcrops of deep-seated rocks are exposed at the flanks of the rift valley. The tectonic mechanism of the lower crust and mantle rocks exhumation process is connected with very large offsets along the detachment faults, resulting in a forming oceanic core complex (OCC) (Smith et al., 2006; MacLeod et al., 2009). The SMS related to OCCs are represented by such ore clusters as Ashadze, Logatchev, Semyenov, and some others (Table 1) and are increasing steadily in number. This fact in combination with widespread OCC formation at the slow-spreading ridges (Escartin et al., 2008) and high grades of metals in SMS related to OCCs has provoked considerable scientific and economic interest in these types of deposits. It could be mentioned in this regard that the first two applications to the International Seabed Authority for prospecting and exploration of sulfides have been submitted for the areas in the spreading centres with wide distribution of the core complexes.

Jan 1, 2011