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By Daniel Brutto

Environmental considerations are a key driver within the marine mining consenting process across different national and international legislative regimes and are critical in shaping the global public perception of the industry. As a result, it is vital that mining companies seeking to operate within marine environments establish a robust understanding of the sensitivities of the seabed environments in which they are active, the impacts of their activities and the ability of the environment to recover from these impacts. The significant risks of failing to do so include an inability to either obtain or maintain operating permits. The risks can be mitigated by the common application of existing seabed biological expertise in baseline assessment and monitoring. The key ingredients of a fit-for-purpose, cost-effective seabed ecological assessment include early consideration of ecological issues within the project life-cycle through undertaking detailed desk-top studies as-wellas the multiple-use of data that have been acquired as a consequence of prospecting processes, with such data including remote acoustic data, seabed imagery and sediment samples. These data can be used to inform the design of robust benthic baseline surveys which provide adequate information on the ecological character of the environment in question and habitats and species of conservation importance - decreasing project risk and increasing the likelihood of securing consent.

Sep 14, 2011

By Rolf B. Pedersen, Ingunn H. Thorseth, Håkon Dahle, Ingeborg E. Øklandm, Linn M. B. Olsen

Weathering of sulfides and the generation of acid mine drainage (AMD) is a well- known environmental issue in on-land mining. The process can release potentially toxic compounds and heavy metals to the environment and is highly influenced by microbial activity. However, the weathering of sulfides in deep-sea environments is not well studied. In 2014 we therefore deployed two titanium incubators filled with freshly ground pyrite grains into an inactive part of the hydrothermal sulfide mound of Loki´s Castle vent field, aiming to study the in-situ seafloor weathering of the freshly exposed sulfides. Each incubator had five chambers placed in a depth profile, where the upper chamber was exposed to the bottom seawater. After one year of exposure, one incubator was collected and analyzed for weathering features and microbial colonization and community composition. In addition, one sediment core (25 cm deep) was collected from the sulfide mound in close vicinity to the incubators, and another core (45 cm deep) was collected from the (hemi)pelagic sediment just outside the sulfide mound. The cores were analyzed for geochemical composition of the solid material and porewater, and the microbial community composition aiming to define the redox zoning and dominating geomicrobiological processes in the natural deposits, and to unravel how these processes influence the mobility of heavy metals during sulfide weathering. Scanning electron microscopy (SEM) revealed development of Fe-oxyhydroxide weathering rims on the pyrite grains in the incubator chambers. Spalling of the rims on the most weathered grains, exposing fresh pyrite surfaces to oxidation, was commonly observed. The SEM investigation also revealed a positive correlation between weathering degree and microbial community density. Preliminary results from the microbial community analysis show a high relative abundance of putative sulfide oxidizers, suggesting that the community is governing the degradation of pyrite.

Jan 1, 2018

By S. Jeffress Williams

Continental shelf margins are dynamic sedimentary environments that contain important benthic habitats and support many functions such as navigation, national defense, cables, pipelines, trawling, and oil and gas and mineral extraction. Coastal margins also contain resources such as sand and gravel aggregates, which are becoming increasingly important for beach nourishment to mitigate coastal erosion and enhance recreation and to restore degraded coastal ecosystems. Existing geologic maps of the seafloor and sub-bottom sedimentary character, morphology, texture, composition, and other seafloor properties are not available for some regions, are out of date and not inclusive of the massive data collected during the past several decades, and are not in GIS-based digital formats. New geologic maps, based on unified and integrated national digital datasets, showing the sedimentary character of continental margins are critical tools for both research to better understanding the geologic history and processes of continental margins as well as the distribution of habitats and resources and for managing coastal-marine resources. The majority of existing seafloor maps are decades old and do not include recent data from mapping surveys, seabed sampling and observation carried out by federal agencies, universities and industry. Because continental margins are increasingly important, comprehensive and integrated databases are needed to produce GIS-based digital maps displaying information such as seafloor geology, sediment character, texture and distribution. To meet the need for a unified database of seafloor sedimentary character, the USGS is conducting the Marine Aggregate Resources and Processes project, a national assessment of marine sand and gravel with federal, state, and academic partners.

Jan 1, 2004

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 Nobuyuki Okamoto

The present three-year long phase of the SOPAC/Japan Deep Sea Co-operative Mineral Resources Programme [Programme], commenced in 2000. The Programme has been funded by the Government of Japan through the Japan International Co-operation Agency (JICA) and the Metal Mining Agency of Japan (MMAJ), since 1985. Field survey activities and associated data analysis and interpretation, for the Programme, has largely been carried out by the Deep Ocean Resources Development Co., Ltd. (DORD). The Government of Japan has, since 1982, recognised DORD as one of its ? Pioneer Investigators? for manganese nodules in the Clarion Clipperton Fracture Zone . Although the objective of this paper is to present the results of the drilling cruise that was conducted from December 2001 to January 2002, within the North Fiji Basin, in Fiji?s EEZ, it will also seek to provide a broad overview of the results of the cruise conducted within the Cook Islands in May to June 2000, as well as present preliminary results of the cruise conducted in the Marshall Islands in June to July 2002.

Jan 1, 2002

By T. Kuhn

The Logatchev hydrothermal field is situated on the east inner flank of the rift valley of the MAR at 14°45?N and is hosted by serpentinized peridotites and minor gabbronorites while basalts are subordinate. Hydrothermal precipitates recovered from the Logatchev field during a recent R/V Meteor cruise include massive chalcopyrite chimneys, massive pyrite crusts, silicified breccias, abundant secondary Cu-sulfides, red jaspers, abundant Fe-Mn-oxyhydroxides as well as atacamite and Mn-oxides (Kuhn et al., 2004). Previous results of hydrothermal fluid studies in the Logatchev field are somewhat at odds with theoretical models of ultramafic-seawater reaction. Butterfield et al. (2003) suggested that the Fe component of orthopyroxene plays the more important role compared to olivine in ultramafic-hosted hydrothermal systems. This consideration is supported by the recovery of large amounts of Opx-rich gabbronorites and orthopyroxenites in the Logatchev field (Kuhn et al., 2004). A possible tool to constrain the contribution of the different rock types (ultramafics, mafics, MORB) to a seafloor hydrothermal system is the systematic analysis of 187/188Os ratios of the host rocks as educts and the sulfides as products. For instance, abyssal peridotites mainly display low 187/188Os ratios (<0.127); in contrast MORB and gabbronorites have radiogenic ratios of >0.13 (Snow and Reisberg, 1995), orthopyroxenite has ratios of about 0.174 (Büchl et al., 2002) and seawater has an ever higher 187/188Os of about 1 (Sharma et al., 1997). Therefore, massive sulfides predominantly leached from ultramafic rocks should have Os isotopic ratios plotting on a mixing line between the ultramafic rocks and seawater (in a 187/188Os vs. 1/Os diagram), whereas those derived from MORB, gabbronorites and/or orthopyroxenites will be plotting on different mixing lines.

Jan 1, 2004

By A. Ivanova

The continental shelves occupy a vast area of Russia and contain complexes of commercial placer minerals. Of prime importance are Cenozoic placers of valuable minerals including gold, cassiterite, diamonds, chromite, platinoids, and minerals of titanium, zirconium and rare earth elements, biogenic amber and fossil ivory (1). Commercial placer minerals are associated with shelf placer formation zones (SPFZ). These zones are located at junctions of marginal orogens and shelf troughs in morphostructures where upwarping, subsidence, and sign-variable neotectonic movements are not significant. The SPFZs are characterized by ancient buried leveling planes with mantles of waste, series of wave-cut aggradation terraces on land and beneath the sea, and drowned and buried stream valleys. The occurrence of mineral placers in the SPFZs was caused by endogenic mineralization and exogenic placer hosted formation. Concentrations of commercial biogenic minerals are associated with areas of burial of biogenic material (release of resins by plants and theriofauna thanatocoenoses) and with their transition zones. Since the Oligocene, alternations in marine transgression-regression have dominated the shelf areas. This has resulted in the formation of polygenic placers. Climatic conditions are of great importance: warm and humid climate in the Paleogene-Neogene changed to colder climates in the late Pliocene (polar type sedimentation; formation of permafrost strata and sea glaciation). These events are responsible for the regularity in placer formation during the Cenozoic in which the early Cenozoic (Eocene-Oligocene-Miocene) and late Cenozoic (late Pliocene-early Pleistocene and late Pleistocene-Holocene) epochs are prominent.

Jan 1, 2004

By Takashi Ito

Numerous studies have examined the distribution of deep-sea manganese deposits throughout geologic history. Here I summarize the recent results, focusing on the frequency of occurrence, burial age and mechanism, and the paleoceanographic implications.

By Wonn Soh

As for Earth, where human beings live, approximately 70 % of its surface is covered by oceans. Today, advanced technology has led us to understanding the abyssal ocean floor through the use of submersibles and ROVs (remotely operated vehicles) for the last 30 years. Furthermore, the oceanic crust beneath the abyssal floor still remains an unexplored scientific frontier due to the lack of a direct approach. Exploration of this frontier is required to enhance our understanding of the mechanism of the M.8 class plate-subduction-type earthquake, of generation of the big tsunami, that caused the disaster, and of the paleo-global environmental change as well as of the origin of life as viewed in deep water thermal vents.

By B. S. Ingole, S. Jai Sankar, A. B. Valsangkar, R. Sharma, B. Nagender Nath, N. H. Khadge, P. A. Loka Bharathi

After the simulated ‘mining’ experiment (INDEX) in the Central Indian Ocean (in 1997); the restoration of benthic environment was monitored for 4 years (2001-2005) at 5 locations in and around the test site and at 3 reference stations (20-80 km) from the test site. A comparison of long-term monitoring data with the pre-mining and post mining observations has shown that: • The concentration of silt fraction which was the highest (50-60%) at most locations during ‘pre-mining’ and ‘post-mining’ phases, had reduced (40-50%) during monitoring phases. • There was a corresponding increase in clay concentration (50-60%) during the monitoring phase, implying change in the size of sediment particles settling on the seabed, a trend that was also observed at the reference locations. • The initial increase in water content and decrease in shear strength after the experiment, which appeared to be returning to normal in monitoring-1 (2001), was reversed during subsequent monitoring phases (2002-2005), indicating changes in benthic environmental conditions. • Sediment organic matter and pore-water chemical data have not only indicated partial restoration of geochemical properties after the experiment, but also cyclic changes during the monitoring period.

Oct 15, 2007

By ?. V. Kabanov

n considered operation hydraulic and kinematic circuits of deep-water installation for sampling a ground from a sea-bottom are submitted. Control by setters is made remotely from a service station with the help of a system of telemechanics. Migration of apparatus along a bottom is ensured with the help of force of a response of a jet and Archimedean force. The mathematical exposition of the device composed and computer simulation is Design parameters are defined and static performances are obtained. Operation is in a stage of manufacture of working drawings. There are patents of Russia.

Jan 1, 2005

By J. Robert Woolsey

The Marine Minerals Technology Center (MMTC) was established by Congress in FY 1988 as part of the Mineral Institutes Program, administered by the U.S. Bureau of Mines under the auspices of the Department of the Interior. The primary objective of the MMTC is to encourage the development of selected mineral materials from U.S. seabeds by providing opportunities for appropriate engineering systems research, development, and technology transfer within academic, government, and industrial communities. The center will also provide the leadership and facilities required for the education and training of the nation&apos;s scientists and engineers in the field of ocean mineral development. Because of the broad spectrum of study encompassed by the field of ocean mining and mineral resources, the MMTC is organized to include separate divisions for nearshore and deep ocean research. The Continental Shelf Division is administered by The Mississippi Mineral Resources Institute (MMRI) of the School of Engineering at The university of Mississippi. Operational activities will be based at the John C. Stennis Space Center near Bay St. Louis, Mississippi and the Gulf Coast Research Laboratory, Ocean Springs,

Jan 1, 1988

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 Andrew Bellamy

A thorough appreciation of the origin, formation, preservation and geometry of marine sand and gravel deposits is central in demonstrating that their extraction by dredging does not affect coastal processes or marine life. Geological evaluation underpins wave, tidal and sediment transport modeling and assists in predicting the nature and extent of seabed change during and after dredging. Marine sand and gravel deposits in the English Channel, southern North Sea and parts of the Irish Sea are of predominantly periglacial fluvial origin and record long histories of valley and floodplain cut and fill associated with Quaternary climatic and sea level oscillations. In the Bristol Channel, the influence of marine transgression and tidal dominance in sorting proglacial outwash deposits is evident in the distribution of sandbanks, scoured channels and gravel lags of this region. These deposits are relict and are unrelated to coastal sediment dynamics. Their extraction leaves seabed depressions which monitoring shows remain unfilled. The resultant offshore bathymetric changes and sediment removal in over 10 m water depth are not transmitted to the coastal zone as beach drawdown, wave height increases or sediment starvation. Applications for new aggregate dredging permissions in UK waters must be accompanied by an EIA and need to make a convincing case that the dredging will not affect rare or declining species and communities of marine life. Seabed recovery rates post dredging are now investigated and understood with reference to geological setting and the uniqueness of the sediment/biological character (biotope). Investigation of the continental shelf by the Industry and others reveals the large extent of gravel-dominated biotopes relative to commercially viable deposits.

Jan 1, 2004

By Akira Usui

Iron and manganese are very mobile metallic elements in the surface aqueous environment, particularly in the oceans. The elements are easily precipitated as oxides or dissolved back into water, controlled mainly by redox conditions, and the oxide precipitates often selectively accumulate other metallic elements. We have found clear evidence of fine-scale variations in chemistry, mineralogy, isotope composition and microstructures within various iron-manganese nodules and crusts, such as in the deep-sea basins and seamounts of the Pacific Ocean, and in shallow waters in the Baltic Sea. The patterns of variation with depth (that is time-lapse profiles of the deposits) are often correlated among samples and sometimes between remote localities. These fine-scale variations most probably reflect past depositional conditions and possibly image the environmental change, although they remain to be correlated to any physicochemical, geological, or oceanographic parameters. The hydrogenetic ferromanganese crusts have grown widely in the northwestern Pacific, accelerated by intensive circulation of oxygenated bottom waters during the last several millions of years, or earlier. The fine-scale (in millimeter) in-depth compositional and textural patterns with Be-10 growth-rate curves suggest significant changes in growth rate and also occasionally show a common microstratigraphic pattern among samples. Some of the samples indicate a correlation in growth pattern between remote locations, while others suggest short-range difference of oceanographic conditions with water depths.

Jan 1, 2004

By L. B. Khershberg

Marginal seas of the Russian Far East constitute the northwestern segment of the Pacific underwater belt distinguished by distinct metallogenic specialization of shelf-extended ore-bearing magmatic complexes and associated polycyclic mineralization. The coastal part of this vast region is known to contain both multiple placer manifestations and deposits, and non-metalliferous minerals. The latter are sedimentary deposits, the products of weathering, which contain re-deposited placer minerals in industrial concentrations developed on the shelf by certain geological processes. The shelf part of the Far Eastern seas is a seawater-filled continental margin. Complex geophysical mapping and drilling from ships of shelf sedimentary thickness and foundation has revealed the units of contemporary and ancient relief accompanied by formation of industrial concentrations of placer gold, cassiterite, titanium-magnetite, zircon, monzonite, and other components at different stages of placer formation. According to the information collected by prospecting by ?Dalmorgeologia? Co. Ltd. and other companies, placer-host structures within trans-placer-concentrating structures (land-shelf) are: shelf-extended river plains, contemporary and ancient shorelines, beaches, drained areas, spits, bars, detritus deficit zones, and terraces and bodies accumulated underwater in the areas where along-shoreline flows unload their detritus. They all could be used as criteria/signs for mapping and targets for placer prospecting.

Jan 1, 2004

By Akira Usui

Platinum is one of the most rare elements in the earth?s crust, but it is significantly enriched in some hydrogenetic ferromanganese crusts in the ocean. The element is essential to the electric industry and is believed to be of importance as a raw material a future fuel-cell industry. The earlier reliable chemical analysis of platinum-group elements (PGE) of ferromanganese crusts have indicated a variety of concentrations of Pt in the range of 100 ppb to a maximum of about 1 ppm, but little is known about the elemental abundance in ferromanganese crusts on fine-scale, or the geochemical behavior and form of the element. The chemical and mineralogical forms of platinum and its group are important in planning the methods of mineral exploration and extraction of the elements from of ferromanganese crusts. We attempted to characterize the distribution pattern within a cobalt-rich crust on the fine to microscopic scales by using reflecting microscope, scanning electron microscope/energy-dispersive spectroscopy, electron microprobe X-ray analysis (EPMA), ICP-mass spectroscopy, X-ray absorption near edge structure (XANES), small-focus XRF, and X-ray diffraction (XRD). These data indicated a wide range of Pt concentration from 150 to 700 ppb within a crust, though we found no distinct inter-element correlation or mineralogical control. Under the reflecting and electron microscope, no distinct Pt-bearing minerals or particles were identified. Small-focus XRF indicated no uneven distribution in any particulate matter, but all areas are less in abundance than the detection limit of about 10 ppm. Our tentative conclusion is that zero valence Pt0 (as suggested by XANES) is dispersed in the form of submicroscopic material most probably within ferromanganese minerals, and therefore, Pt-rich mineral particles may not be a major carrying phase.

Jan 1, 2005

By Roy Nilsen, Aravinda Perera

With the exponential growth of demand for minerals and need for diversification of supply channels, deep-sea mining is rapidly becoming inevitable. Productivity of underwater mining technology is salient to justify the deep-sea explorations. Methods for enhanced productivity of mobile mining equipment in a system level are investigated in this paper. Lessons learnt from the land-based mining has been the basis of this investigation. In general, mining productivity can be enhanced in two ways; firstly, by maximizing the amount of recovered material per unit time and secondly, by minimizing the cost of operation per unit material. Equipment that enable faster excavation, loading and transport in the seabed contributes significantly in increasing the amount of slurry per unit time. Improved mean time between failures (MTBF) of mining equipment will reduce the operational down time, thereby, contribute to maximize the amount of mined material per unit time. Several factors influence the operational cost minimization per ton of slurry. Higher efficient motor drive systems including the motor and PWM-fed inverter not only will save power but also will emit lesser heat thus the heat management can be less complex. This leads to more compact drive systems that allows higher power density, thus increased payload weight per empty vehicle weight. An energy storage method in the form of an utracapacitor in the electric drive system will also save the energy supply from the upstream.

Jan 1, 2018

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 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