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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 Akira Usui, Sayuri Kubo, Satoshi Tokeshi, Shingo Kato, Katsuhiko Suzuki, Teruhiko Kashiwabara

"INTRODUCTIONFerromanganese (Fe-Mn) crusts are a kind of marine chemical sediment composed of Fe and Mn oxy-hydroxides as well as small amounts of clastic sediments, which are ubiquitously found on the surface of slopes of seamounts and oceanic plateaus at depths from 900 to 5500 meters below sea level (mbsl). Fe-Mn crusts contain extremely high concentrations of useful minor metals such as Co, Ni, Te, REEs, and thus are expected as submarine mineral resources. Also, Fe-Mn crusts record the change of chemical compositions of seawater during last several tens million years, which allow us to obtain clues to clarify the paleoenvironmental conditions at the time of its deposition. However, occurrence, chemical compositions, microbial community and growth patterns of ferromanganese crusts are yet fully understood. Hence, a comprehensive study on the genesis of ferromanganese crusts, such as growth rates and enrichment processes of elements, is required to better understand their resource potential as well as their applications to paleoceanographic study.Based on the resource potential of ferro-manganese crust, the project entitled “Next- Generation Technology for Ocean Resources Exploration” was launched as one of the governmental projects to develop the exploration technology based on the scientific research on the submarine resources such as hydrothermal deposits (e.g., a poster by Kawada et al.), ferro-manganese crusts. We have made several research cruise to seamounts in the north-western Pacific such as Takuyo-Daigo and Takuyo-Daisan seamounts (Fig. 1) ."

Jan 1, 2017

By N. Wang

The City of Honolulu mines sand from nearshore deposits for beach maintenance. The suction dredging operation creates a discharge plume which is carried by currents and other motions until it settles out of the water column. The dispersion of such a plume is influenced by distribution of particle size, as well as site dynamics. Interest in dispersion characteristics stem$ from concern about possible deleterious influences of such a plume on the nearshore environment. The behavior of such plumes has been modeled by Brandsma and Divoky (1976), as well as others. This study is an attempt to calibrate a plume model (modified from Brandsma and Divoky's model by Wang), using concentration, turbidity, and fluid velocity measurements of a small plume taken under field conditions. This calibrated model could then be used to predict dispersion characteristics of a much larger plume. Sand suction-dredged at a depth of 12m with a four-inch pipe and discharged at midwater was used to create a test plume closely simulating the conditions found during regular mining operations. Water samples containing suspended material were taken at varying distances from the discharge, from which concentrations were measured in the lab. Transmitted natural light measurements were used to provide estimates of turbidity. Current velocities were measured using current meters, as well as drogue-following methods. These data were then used to help estimate the vertical diffusion coefficient in the model.

Jan 1, 1991

By Tae-kyeong Yeu

KIOST has developed the pilot mining robot, named MineRo ?? from early-2011 to mid- 2012. The robot consists of two unit-modules having an identical mechanical structure and hydraulic system. One unit-module has two track systems, two pick-up devices, two crushers, one lifting pump and one thruster. The pick-up device is fitted on the frame of the track device. All actuators are driven hydraulically, which are manipulated by valves and the controllers. Each unit-module is equipped with one dual HPU of 250kW / 4,000V. PWM-16 (INNOVA AS) as hydraulic valve controller is adopted, which outputs PWM signals of 16 channels and can be used under pressure in oil-filled box. To measure angular velocity or displacement of hydraulic actuator, turbine-type flow-meters are adopted. The flow-meter has RF (Radio Frequency) type pulse detector, which extends the flow range by eliminating drag on the rotor. Two track motors, two crusher motors, lifting pump, one thruster can be controlled their velocities through feedback of the measured flow-rates. As well as the flow-rates, the states of the hydraulic system such as hydraulic pressures, temperatures, leakages are measured through a self-developed flow-pressure canister. In that canister, multi-channel amplifier boards are installed, through which the vast amount of data is acquired and transmitted to the main controller using serial communication.

Sep 14, 2011

By Gerald R. Dickens

Massive sulfide ores and Fe-Mn oxyhydroxide precipitates represent two extremes of a spatial continuum of hydrothermal deposition along oceanic ridges. Elemental variations across this continuum are of interest to economic geologists as a prospective geochemical exploration tool. Theoretical considerations suggest that certain physical and chemical parameters can be used to model compositional variations within the far-field (i.e., Fe-Mn oxyhydroxide) component as a function of distance from ridge axis; however, testing and verification of such models generally has been precluded because the few available distal hydrothermal sediment sequences have been sampled at low resolution and/or are highly diluted with biogenic components (e.g., siliceous and calcareous tests). Recent ocean drilling (ODP Leg 145; Sites 885/886) in the North Pacific successfully recovered an extensive record of "biogenic-free" distal hydrothermal precipitates from an area approximately 60 km south of the Chinook Trough at longitude 168.1 °W. Geophysical and geomorphological evidence suggests the Chinook Trough is the southern lithospheric scar marking initiation of late Cretaceous north-south rifting, implying that recovered hydrothermal materials record distal hydrothermal precipitation from the now-subducted Kula-Pacific spreading ridge. The Chinook Trough hydrothermal sequence is a continuous 15 my record of "biogenic-free" hydrothermal Fe-Mn oxyhydroxide precipitation mixed with eolian clays. It was deposited during the late Cretaceous, early Paleocene (80-65 Ma) as the perpendicular distance from ridge axis increased from 75 to 600 km. A high-resolution geochemical analysis of this hydrothermal sequence reveals distinct trends for the up-core (equivalent to increasing distance from ridge) distribution patterns of Fe, Sc, As, and rare earth elements (REE). Iron concentrations exhibit an S-shape distribution pattern with respect to increasing

Jan 1, 1994

By Cheng Xiangzhou

The China's Pioneer area includes two parts. The topography in the western part is very different from that in the eastern one. The distribution of the manganese nodules in these two regions differs correspondingly China Ocean Mineral Resources Research and Development Association (COMRA) will take appropriate measures so that the next development will be adapted to the features of its potential minable area.

Jan 1, 1996

By Stanley R. Riggs

Onslow Bay is a broad, shallow, high-energy shelf system bounded by the Cape Lookout and Frying Pan shoals. It is generally a sediment-starved shelf system dominated by hardbottoms with a scattered and discontinuous veneer of mobile Holocene sediments. Phosphate-rich beds of the Miocene Pungo River Formation crop out in a belt 150 km long and up to 50 km wide across the continental shelf in Onslow Bay, North Carolina. Previous research has demonstrated that a few of these beds contain vast quantities of potentially economic phosphate resources that occur in the surface and shallow subsurface sediments. Onslow Bay contains five phosphate-bearing beds predicted to include up to 20.7 billion tons of in-place phosphate concentrate with total sediment grades ranging up to 22.9% P2O5 and adjusted average concentrate grades of 29.8% P2O5. These phosphates are lithologically and chemically similar to phosphates currently being mined in the nearby Aurora phosphate district in North Carolina. Various lithologies of the Pungo River Formation and associated rock units of Oligocene and Quaternary age crop out on the sea floor to form extensive hardbottom habitats that dominate almost 100% of Onslow Bay. A large proportion of these hardbottoms appear to be sea floor deserts, whereas others are virtual oases with rich associations of benthic organisms. These important differences in benthic community structure appear to be greatly influenced by one or more of the following variables: 1) geologic framework (geologic formation, hardbottom composition, morphology, and spatial orientation relative to dominant currents and waves), 2) texture, movement, and accumulation of surface sediments, and 3) flow rates and chemical composition of discharged submarine groundwater.

Jan 1, 1992

By Marco Figoni

The increased interest on deep water minerals resources is a challenge for both mining and oil industry. The exploration and production of oceans minerals require a synergy between of different technologies. While mining industry is leading the dredging and processing part of the system, oil industry is contributing through development of ore lifting technology based on existing subsea knowledge. The paper presents an overview, based on published projects around the world, of different approaches to marine mining. Several exploration techniques and offshore production systems were already designed and assessed, all of them with apparently positive results. Exploration phase is well advanced and in continuous expansion allowing the discovery of increasing resources around the world of different nature but production can be considered to be in an early stage. Different from onshore mining, subsea operations require a closer cooperation with international and local authorities to preserve as much as possible the environment. There are still many uncertainties at respect and all the exploration process must be carefully evaluated to allow subsea mining to develop in a sustainable manner. Technically, mining at seabed was already demonstrated and the process is based on three main components, namely seafloor mining tools, riser and lifting system and production vessel support. This layout is based on the concept that ore must be disaggregated at seafloor first, transported to surface in form of slurry that must be dewatered before loading to be transported to processing plants onshore. The challenges are rising because the environment and safety must be taken into consideration as a priority when evaluating the efficiency of the system. The most critical challenges regarding the production operations, especially in deep water are the deep-sea excavation process, the transport of large slurry volumes, the slurry abrasivity, the power supply management and the subsea

Sep 14, 2011

By Chan Min Yoo, Jung-Keuk Kang, Wonnyon Kim

Recently high-resolution paleomagnetic age determination of ferromanganese crust in less than millimeter scale has been successfully carried out using a superconducting quantum interference device microscopy magnetometer (SMM). However, it has not been clearly identified how the crust is keeping ancient geomagnetic field records. Here we try to identify magnetic mineralogy of the crust obtained in the Magellan Seamounts, the West Pacific (~20 °N). As a record, age of the crust used in this study is extended to ~10 Ma at ~40 mm depth and ~28 Ma at ~100 mm depth, respectively, based on the combination approach of SMM measurements, Be-isotope and Co-chronology. Thermal demagnetization revealed a Curie temperature of ~560oC, corresponding to (titano)magnetite. Component analysis of isothermal remanent magnetization identified a presence of two types of magnetite. Measurements of first order reverse curve showed a dominance of non-interacting single-domain magnetite, which is one of the intrinsic feature of biogenic magnetite. Although most of the magnetic particles on transmitted electron microscopy are covered by amorphous Fe-Mn minerals, some are observed as a prototype of biogenic magnetite showing a chain of ~10 nm sized magnetite cubes. However, a magnetite signal (i.e., Verway transition at ~ –120 oC) was not detected in low-temperature treatment probably due to surface oxidation of magnetite. Contribution of interacting magnetite of detrital origin is <30% throughout a crust. Interestingly, contribution of detrital magnetite is almost three times higher since ~10 Ma. At this boundary, a growth rate of the crust is double up and flux of other detrital signals, including Al, Mg, Ti and Zr, are also increased.

Jan 1, 2017

By D. S. Cronan

Pitcairn Island, the last remaining British Colony in the Pacific Ocean, falls in the S.E. Pacific. Its location, on top of a hotspot volcano, suggests the presence of submarine hydrothermal deposits in its EEZ. Such environments are known to contain hydrothermal mineral deposits, as in the case of Loihi submarine volcano near Hawaii, and Macdonald and Teahitia-Mehitia seamounts in the South Pacific. The hydrothermal deposits in these areas are formed as a result of the interaction of seawater with hot volcanic rock, producing a hydrothermal fractionation sequence comprising sulphides of Fe, Cu and Zn, oxides and silicates of Fe and oxides of Mn. In 1988, a GLORIA survey from the RRS Charles Darwin confirmed the existence of recent volcanism within the Pitcairn Island EEZ. A later bathymetric and sampling survey by the FS Sonne of the region round Pitcaim Island revealed submarine volcanoes approximately 80 km ESE of the island. Hydrothermal mineral deposits were recovered from them, and comprise finely laminated crusts of Fe oxides containing up to 50% Fe, and laminated hydrothermal Mn crusts up to 5 cm thick. Both morphologically and chemically the latter are similar to those from mid-ocean ridge and island arc settings, containing up to 50% Mn, associated with sulphides, and represent first discovery of such deposits associated with mid-plate "hotspot" volcanoes. Massive sulphide deposits are thought to occur within the volcanic pile.

Jan 1, 1992

By S. Jeffress Williams

The U.S. Geological Survey (USGS), over the past three decades, has carried out a spectrum of geologic surveys and research in marine areas of the Exclusive Economic Zone (EEZ) around the U.S. and its territories as well as in the Great Lakes region. Regional and topical studies have been undertaken throughout the range of marine environments: estuarine, tidal wetlands, coastal and nearshore, shelf, slope, and the deep ocean basins. The Survey&apos;s coastal and marine research programs consist of four elements shown in Table 1. The first includes studies using interpretations of bathymetry, seismic-reflection and sidescan sonar data, and analyses of sediment grab samples and cores to develop an understanding of the geologic framework. Information on the geologic setting, including the subbottom structure and stratigraphic relationships, and the geologic history and evolution of the areas surveyed are important parts of the program objectives.

Jan 1, 1992

In early 1990s, the Korean government has launched a deep-sea research program to secure the stable long-term supply of strategic metallic minerals including Cr, Cu and Ni. Through the pioneering surveys, Korea registered 150,000 km2 of Mn-nodule field in the Clarion-Clipperton area, the NE equatorial Pacific to the international sea-bed authority (ISA) in 1994. Following the ISA exploration code, the final exclusive exploration area of 75,000 Km2 was assigned in 2002, based on results of eight-year researches of chemicophysical properties of nodules, bottom profiles and sediment properties. Since that time, environmental studies, mining technical developments including robot miner and lifting system and establishment of smelting systems were accompanied with the detailed geophysical studies to decipher the priori mining area until 2009. Major points of the recent Korea Mn-nodule program are deployed on a commercial scale until 2015. In order to meet the goals, detailed 25,000 scaled mining maps in the priori area will be prepared, which can provide operation roots of the miner. In addition, an environmental-friendly mining strategy will be pursued based on the environmental impact test and environmental monitoring.

Sep 14, 2011

By Kokichi Iizasa

Kuroko-type deposits exist in Japanese EEZ. Some of them are present in the Izu-Ogasawara oceanic island arc south of Tokyo. Major two Kuroko-type deposits occur in the area. One is the Sunrise hydrothermal field occurring on the caldera floor of Myojin knoll, which is likely to be the developed stage in sulfide mineralization. Another is present in the crater of Suiyo seamount that is the early stage of sulfide mineralization. The two deposits are here presented on the growth history based on samples recovered by Benthic Multicoring System (BMS).

Jan 1, 2002

By Fred C. Dobbs

To effectively manage the potential environmental impacts of deep-sea mining of manganese nodules, we need to know substantially more about the effects of sediment redeposition on abyssal communities and the time scales of recovery from such effects. As an initial step towards a predictive understanding of mining impacts on abyssal benthos, we are conducting a series of biological studies within the framework of the Benthic Impact Experiment (BIE). Mining operations will cause resuspension of sediments across extensive areas of the abyssal Pacific Ocean. The resultant plumes likely will produce redeposition layers, ranging from a few sediment grains in thickness to > 1 cm, over thousands of square kilometers of the seafloor. The impact of such redeposition on abyssal benthic communities is exceedingly difficult to predict. While there has been speculation that redeposition of 1 mm or less will exert deleterious effects, there has been very little testing, and the BIE will provide the first in situ test of redeposition impacts. In a series of cruises before and after controlled resedimentation, we are collecting biological samples to determine the undisturbed state of the ecosystem, the immediate effects of disturbance, and the time-course of recovery resulting from quantified levels of resedimentation.

Jan 1, 1992

By Daisuke Monoe, Kisaburo Nakata, Rika Takeuchi, Tetsuo Yamazaki, Tomoaki Oomi, Tomohiko Fukushima

There are generally two methane passes in conjunction with the seafloor natural cold seepages, as is schematically shown in Fig. 1. The first pass consists of the coupled anaerobic oxidation of methane and anaerobic sulfate reduction, as well as sulfur oxidation in the bacterial mats and immobilization thereafter in the sediment layer and on the seafloor. Through the first pass, calcium and organic carbonates are formed in biological and chemical processes from the methane (Luff and Wallmann, 2003; Luff et al., 2004). The detailed structure of the seafloor methane consumption process unit and its biological and chemical processes were introduced in Yamazaki et al. (2005). The other pass consists of direct bubbling into the water column. Through this pass, organic carbonate is formed with biological oxidation, and a small amount of the methane escapes into the atmosphere. Methane flux is supplied to these two passes through the sediment layer from the deeper structures. The structure of the methane supply process unit was introduced in Yamazaki et al. (2006).

Sep 24, 2006

By C. W. Devey, K. S. Lackschewitz

The mineralogy and geochemistry of hydrothermally altered wall rocks from different modern basaltic- and felsic-hosted hydrothermal fields at seafloor spreading centers and convergent margins have been studied to determine the characteristics of different types of alteration and to calculate the magnitudes of elemental exchanges between seawater and wall rock.

Aug 24, 2006

By Curtis Clement

Williamson & Associates, Inc. has developed a marine mineral exploration tool using an induced polarization technology (IP) under license from the US Geological Survey. Developed by Jeff Wynn at the USGS, this method has gone through several prototyping stages and is now in commercial use to map offshore ilmenite deposits. Preliminary results of a recent resource mapping program are discussed as well as potential applications in the detection and quantification of other minerals in marine sediments.

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 Hunsoo Choi, Sang-Mo Koh

Manganese nodule, the aggregate of fine grained manganese oxide minerals, is very brittle and fragile. In exploitation of manganese nodule, manganese nodules are easily broken into small pieces or powder during collecting and lifting from the sea floor. The broken manganese nodule under few millimeters and bottom sediment pumped up with manganese nodule affect to the lifting process. In this study, we tried to understand the physical properties of the powdered manganese nodule and bottom sediment, and to know the effect which may be rised to the actual mining of manganese nodules.

By In Kwon Um

The XRF Core-Scanner system performs non-destructive analysis of elements from Mg to U, in concentrations of ppm levels on split cores with digital images. Using the AVAATECH XRF Corescanner system, we conducted high resolution element analysis of deep sea sediment cores from Clarion-Clipperton fracture zone of the northeastern Pacific to reveal recent environmental changes. Comparison of data estimated by the XRF core scanner with ICP-AES showed relatively weak correlation coefficients except Mn contents. Down-core variations of most elements seem to be matched with each other and reflect changes of sediment colors. Especially Mn/Al ratio significantly change at distinct color boundaries. The variations of Mn/Al ratio with sediment colors are suggestive of changes in redox condition and further divided into two types probably affected by activities of benthic organisms. Be isotope age datings of select core (BC08-02-13) indicate that the color boundaries are approximately coincident with late Pliocene and Pleostocene also early Pliocene and late Pliocene boundary. Keywords: XRF core scanner, High resolution, C-C zone

Jan 1, 2011