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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 Tetsuo Yamazaki

Deep-sea rare-earth element-rich mud (REE Mud) distributes in pelagic clayey sediment column on ocean seafloor at 4,000-6,000 m deep. The thickness ranges 5-80 m and the burial depth 0-100 m. The REE content ranges 600-2,250 ppm in Pacific and one of the richest, maximum 6,500ppm, has been found in Marcus Is. exclusive economic zone. By applying a conventional hydraulic excavation and lifting methods, the economy of REE Mud mining around Marcus Is. is preliminary examined. Because the waste content in REE Mud is high and the disposal cost in Japan is very expensive, the mining is recognized far away from economy.

Sep 14, 2011

By Michael Johnston

Nautilus Minerals is exploring for high-grade gold, silver, copper, and zinc-rich submarine massive sulphide deposits (SMS) within the territorial waters of the sovereign state of Papua New Guinea. Work to date has shown that these systems contain spectacularly high metal grades. To date a total of 88 surface sulphide grab samples have been collected from Nautilus’ Solwara 1 Prospect within EL 1196 in the Manus Basin, returning average grades of 15.5 g/t gold, 191g/t silver, 10.8% copper, and 4.7% Zn. Drilling in January/February 2006 confirmed the presence of this high grade system, with sulphide intersections up to 19m below the sea floor, with a best intersection of 11.6m at 9.1 g/t Au and 13.1% Cu.

By Tetsuo Yamazaki

The importance of cobalt-rich manganese crusts on the Pacific seamounts for possible future rare metal sources has currently been recognized. The thin layer-type deposit characteristics affect not only the excavation efficiency but also the economy of mining venture. Considering the thin layer-type distribution and the utilization of some rare metals in cobalt-rich manganese crusts, a preliminary economic feasibility of the mining venture is evaluated. Under some preliminary technical assumptions, the possibility of cobalt-rich manganese crusts for future rare metal sources for Japan is examined. The important role of utilization of rare metals in the crusts is highlighted.

Jan 1, 2010

By H. L. Gibson, U. Schwarz-Schampera, Mark Hannington

Ancient ore deposits provide important clues for the understanding of the origin and distribution of modern submarine hydrothermal systems. An analysis of the formation conditions, tectonic settings, and preservation of ancient seafloor mineral deposits from the recent geological past to the late Archean sheds light on the time-space relationships and diversity of mineral deposit types likely to be found in the modern oceans. Microplate tectonics that characterized ancient ore-hosting greenstone belts were strikingly similar to those active in volcanic arc environments of the western Pacific today. In such complex settings, oblique collisions, opposing subduction zones, and rapid changes in stress regimes (e.g., from compressional to tensional and back to compressional) were common, causing juxtaposition of diverse styles of mineralization. The world-class base metal deposits of the late Archean Abitibi greenstone belt of Canada, for example, were formed within a relatively short time span of ~20 m.y., in response to successive arc rifting, back-arc basin development, and exhumation of accretionary complexes along major arc-parallel crustal-scale faults. Similar processes and environments are important settings for metallogenesis in modern submarine volcanic arcs. Active marginal basins of similar size and representing similar stages of evolution are well represented in the western Pacific today and contain a similar suite of mineral deposit types. Examples from the eastern Manus Basin and adjoining New Ireland Basin (PNG) and in the Lau-Tonga-Kermadec arc-backarc system illustrate these similarities. Certain gold-rich volcanogenic massive sulfide deposits at the southern margin of the Abitibi greenstone belt (e.g., Bousquet and LaRonde deposits in the eastern Blake River Gp.) may be important ancient analogs of newly discovered gold-rich black smoker deposits found along the active fronts of today's submarine volcanic arcs.

Sep 24, 2006

By Peter Halbach

Within the frame of the German-Indonesian cooperative Bandamin research project two short cruises (7 station days each) were carried out which led to the Flores-Banda basin located north of the active volcanic arc. This basin is part of a large island-arc subduction-collision system resulting from a complex plate tectonic situation in which three major plates collide with each other. The eastern part of the Sunda-Banda convergent margin also includes the transition from subduction of oceanic lithosphere to collision of the Australian continental crust with the arc. This transitional part is cut and displaced by various large obliquely striking fault systems. Thus, the south eastern and eastern arc segments represent geological conditions which are suitable for the development of hydrothermal convection and potential mineral precipitation. Our study area lies north of the transitional section between Flores and Wetar. We started with a high-resolution bathymetric mapping of 240 km2 in a region some 36 km north of the island of Lomblen. A small submarine neovolcanic ridge was discovered striking approximately NW-SE and consisting of several submarine volcanic structures. In the northwest of the study area, the active subaerial Komba Volcano (Batu Tara) marks the youngest continuation of the ridge system examined. From the ridge we collected fresh and hydrothermally altered volcanics with disseminated sulfides (pyrite, pyrrhotite, markasite, and chalcopyrite), together with ferrugenous gossans.

Jan 1, 2004

By Sup Hong

Herein, concept designs of two different types of mining robots are concerned, which are aimed for developments of deep seabed mineral resources: polymetallic nodules (PMN) and seabed massive sulfides (SMS), respectively. Continuous mining concepts are presented based on technical and environmental feasibility, where the environmental and functional differences for commercial productions are investigated. Needs and roles of versatile mining robots are explained as a key of continuous mining system. The functional requirements and design characteristics of mining robots to satisfy the top requirements from customers are described comparatively. Schemes of axiomatic design and quality function deployment (QFD) are utilized: functional requirements (FR) are defined, technical requirements (TR) are figured out, design parameters (DP) are derived, and degrees of importance of design parameters are evaluated. Analogy and discrepancy in remote operation methods are put side by side. A pilot scale mining robot for PMN and a commercial scale one for SMS are suggested in form of concept designs. PMN mining robot is shaped as a multiple configuration of unit robot modules in side dimension, in which the unit robot module consists of two tracks and two pick-up modules. SMS mining robot is based on a four-tracked vehicle. Main platform is mounted on the vehicle through turn-table. Excavation device consists of two-articulated boom and cutter tool. Crushing-and-pumping units are placed same in both robot platforms.

Jan 1, 2011

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 Jae-Hyung Park

Since the Industrial Revolution, the land resources have been decreased rapidly as the industrialization. And this phenomenon brings to our mind an interest in deep-sea resource(manganese nodule). Hence, Korea has been participated in the development project of exploiting manganese nodule since 1983. Hwang and cho(1998) studied the economic efficiency evaluation of manganese nodule carrier. But they used the TAMU(Texas A&M University) model, and assumed deadweight and velocity of bulk-carrier. If we use some optimization technique, more economic manganese nodule carrier can be selected and evaluated without limited assumption. In this study, we evaluated the economic efficiency of manganese nodule carrier using genetic algorithms(GAs).

Jan 1, 2003

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 Dennis Sánchez Mora, John Jamieson

INTRODUCTION Work by Humphris et al., (2002); Ondréas et al., (2009); Barreyre et al., (2012); and Escartín et al., (2015) has identified active and inactive hydrothermal sites along the Lucky Strike segment. The sites that contain the largest accumulation of known sulfides are located between the north and the southern zones (Figure 1), a vent site area that is referred to as the Main Lucky Strike hydrothermal field (Escartín et al., 2015). Hydrothermal fluid outflow has been linked to a shallow fault network (Barreyre et al., 2012). However, specific constraints on fault geometries have not been determined. Other off-axis sites at Lucky Strike, such as Capelinhos (high temperature vent), and Grunnus (inactive?), as well as a low temperature vent field (on-axis), Ewan, have been described by (Escartín et al., 2015). Given the spatial relationship between the Main Lucky Strike hydrothermal field (MLSHF), and the intersection of northern rift faults with the southern rift faults, a structural analysis of this area can provide insight into the fault controls on fluid flow that leads to hydrothermal venting and sulfide precipitation. METHODOLOGY Structural data (dip direction and dip) was determined using Leapfrog Geo 4.0 software. Bathymetric data was obtained from Escartín et al., (2015) and references therein. The bathymetry was imported into Leapfrog Geo (in UTM format) and, using the structural modelling tool, individual measurements with dip direction and dip data were collected with a focus on the northern volcanic rift and the southern central volcano (Figure 2a). All measurements were taken from what the authors consider as normal faults, and to aid the determination of individual measurements a “face dip” map was constructed, where the bathymetry is colored by slope angle (Figure 2b). All measurements are simultaneously plotted on a stereonet generated by the Leapfrog Geo Software. Data were divided into northern and southern, and western and eastern zones to determine the relationship between hydrothermal venting and the structural geometries at Lucky Strike (Figure 2c). Slip measurements for individual faults were determined along the dip of the fault with a measuring tool. Net slip, heave (horizontal displacement), and throw (vertical displacement) was calculated for each of the zones.

Jan 1, 2018

By Harold Gibson, Ulrich Schwarz-Schampera, Ralf Freitag, Hendrik Mueller

INTRODUCTION Germany has a long history in marine research in the Indian Ocean. The first German scientific cruise started in 1964, followed by a series of state-sponsored research cruises between 1983 and 1995 leading to the first finding of polymetallic sulfides in the Indian Ocean. The research included regional bathymetric, geological, structural, volcanological, petrological and hydrothermal investigations along the Carlsberg Ridge and the Central Indian Ridge (CIR). Early environmental base line studies covered oceanographic and sedimentology aspects. In 2010, BGR took the initiative for the preparation of a license application for the exploration of polymetallic sulfides with the International Seabed Authority (ISA), and prospecting started in 2011 along the southern Central (CIR) and the northern Southeast Indian Ridge (SEIR) in the southwestern Indian Ocean (cruises INDEX 2011 on board R/V Sonne), INDEX 2012 (R/V Fugro Gauss), INDEX 2013/1-2 (R/V Sonne) and INDEX 2014 (R/V Pelagia). After three years of resource-oriented and environmental base line studies, BGR, in order for the Federal Ministry for Economic Affairs and Energy (BMWi), applied for an exploration license which was approved by and subsequently signed with the ISA in 2015. The license gave permission to start a detailed exclusive resource-oriented exploration program in the license area. The program includes the outline of potential ore deposits and a resource assessment but also extensive and detailed base line studies for the sustainable protection of the marine environment in the license area. The license contract has a fifteen years lifetime and may allow the application for a subsequent mining license. The exploration aims at the identification of inactive polymetallic sulfide deposits, formed below former discharge zones of hot hydrothermal fluids on the ocean floor (“black smoker” systems), by advanced and modern exploration techniques.

Jan 1, 2018

By James R. Hein

Low- to intermediate-temperature, diffuse-flow hydrothermal fields and associated mineral precipitates have been found at many locations along oceanic spreading centers, back-arc basin spreading axes, and midplate hot-spots. However, this type of hydrothermal field has not been found in oceanic fracture zones until recently. We mapped and collected samples from an active hydrothermal field in the Blanco Fracture Zone (BFZ) located in the northeast Pacific. The BFZ connects the Gorda and Juan de Fuca spreading centers and is divided into east and west segments by Cascadia Depression, a small spreading center. Small pull-apart basins occur along both the east and west segments. A complex set of basins near the western end of the BFZ includes from east to west, Surveyor Depression, East Blanco Depression (EBD), and West Blanco Depression. The hydrothermal field described here is located in the EBD.

Jan 1, 2001

By Charles W. Finkl

Coastal and marine aggregate (sand and gravel) mining on US continental shelves is a major activity that supplies industrial and commercial demands for these raw materials. Because Pacific, Atlantic, and Gulf coasts contain significant shoreline segments that are in a critical state of erosion, sand-gravel and mixed sediment (sands with a high percentage of silt-plus-clay) deposits are mined in efforts to mitigate land loss. Sandy shores, and to a limited extent gravel coasts, erode by shoreline retreat due to relative sea-level rise and sediment starvation in littoral drift patterns. Mostly gravel shores occur in high latitudes and shorelines often advance seaward due to isostatic rebound following the LGM (Last Glacial Maximum 18,000 YBP). Sandy and fine-grained shores occurring in middle and low latitudes of the conterminous United States are problem coasts that require beach renourishment and reconstruction of barrier islands. Muddy coasts of the Mississippi Delta region are especially problematic because some islands are literally disappearing in response to subsidence. Replacement of sediments lost to the littoral drift system or returned to sedimentary sinks by drowning is thus a critical endeavor that involves annually dredging hundreds of millions of cubic meters of sediments from the continental shelf area. The types of shelf sediments that are amenable to marine mining techniques, their occurrence, and means of detection are highlighted in this paper. Minable Sediments on the Continental Shelf Wide varieties of sedimentary bodies that occur on the continental shelf are amenable to mining for beach renourishment and barrier island (beach-dune-marsh system) reconstruction. Relict terrestrial deposits make up a small but important proportion of shelf sediments that were deposited on coastal plains, now drowned by the post-glacial sea-level rise to form continental shelves. Examples of these deposits include drowned moraines, outwash plains, eskers, and kettles along the northern Atlantic coast in addition to siliciclastics along middle latitude Pacific, Atlantic, and Gulf coasts. Special cases include carbonate sequences along tropical costs of Florida and the muddy coasts of deltas, mostly in Louisiana. Specific types of minable deposits thus include shoreface attached sand sheets, dunes, and ridges in addition to offshore inter-reefal sands (between coral reefs in the Florida Reef Tract), bank deposits, and sand waves (ridges) that extend into US territorial waters. Nearshore siliciclastics include ebb-tidal deltas and bars. Drowned river valleys occur along all three US coasts and can be exploited for their fluvial sands if the covering mud sheets are thin.

Jan 1, 2005

By S. Rajendran

The western continental margin comprises of the southwest coast (Cape Comorin-Mangalore), centralwest coast or Konkan coast (Mangalore-Bombay), northwest coast (Bombay-Gulf of Kutch) and the Laccadives area. Placer deposits of heavy minerals occur in discontinuous patches on the beaches along many parts of the west coast. The richest offshore placer deposits occur along the 25 km stretch of the southwest coast from Neendakara to Kayamkulam. The National Institute of Oceanography (NIO) surveys show that the sediments off the Konkan coast consist largely of silty sand, sandy silt and clay and the concentration of ilmenite is higher than the onshore. The heavy mineral concentration ranges up to 90% and has mainly ilmenite and magnetite with minor quantities of apatite, rutile, zircon, kyanite etc. The heavy mineral sands extend below the clays to water depth down to 20 m. The heavy minerals sands vary in thickness from 2-10 m. Offshore placers can be mined by using wire-line, bucket ladder and hydraulic dredges. Wire-line, bucket ladder and hydraulic dredges. Wire-line dredges may employ drag buckets or clamshell and hydraulic dredges suction or airlift principles. The dredges can be located on flat bottom or catamaran barges. Dredging of very near shore placers may be achieved by operating from land. The bucket ladder type of dredger has greater digging ability and hence can be deployed for mining placers which are partly consolidated or cemented or where the most valuable part of the deposit lies at the contact between the alluvium and the bedrock. This type operates very economically up to 45 m depth and needs minimum power requirement per unit dredged. Suction type hydraulic dredges can be operated very effectively up to 60 m water depths. This system is quite ideal for the inner shelf. The maximum practical economic working water depths for wire-line dredges are about 150 m. With the drag bucket modified into large net buckets, the method can be utilized to greater depths. They can be used in areas of high water currents and swells. The type of bucket can be changed readily with change in the nature of alluvium or substratum. The hydraulic suction dredge is the most suitable system for mining unconsolidated sediments. When the sediments are semi-unconsolidated, a cutter head can be mounted on the lower end of the suction pipe to agitate the seabed.

Jan 1, 1996

By C. R. Pearce, B. Murton, S. Howarth, P. Lusty

"With the expansion of “green” energy technologies, the demand for the critical raw materials required to sustain this growth is increasing. Many E-tech elements, including tellurium (Te) and rare earth elements (REEs), suffer from high supply shortage risk and the need for more diversified metal supply routes is driving research into alternative resources. Hydrogenetic ferromanganese crusts, seafloor deposits of Fe- and Mnoxyhydroxides that form from the direct precipitation from seawater, present a potentially important future source of E-tech elements. With growing interest in the potential wealth of these deposits and the issuing of permits for deep-sea mining and exploration, more work is underway to understand the nature of ferromanganese crust deposits, their elemental concentrations and distributions, and the potential impacts of mining activities.This research focusses on the formation of ferromanganese crust deposits and processes that control the extreme enrichment of elements such as Te, Co and REEs. The crusts were systematically sampled and mapped between ~ 1000 – 4000 m depths using ROV ISIS, from a range of environments, substrates and morphologies from Tropic Seamount (NE Atlantic) in order to determine the seamount-scale factors that control major and trace elemental concentration variations. These factors include depth, surface roughness and micro-bathymetry, location relative to long-term mean current direction and energy, influence of tidal energy dispersion across the seamount, sediment supply, substrate lithology, biological productivity and phosphatisation. The study analyses trace-element characteristics of 100 ferromanganese crust samples alongside standard reference materials NOD-A-1 and NOD-P-1 (US Geological Survey manganese nodules). At this initial stage, we report results from whole rock acid digestion and ICP-MS analyses."

Jan 1, 2017

By Raymond A. Binns

In this first sub-seafloor examination of an active hydrothermal system hosted by felsic volcanic rocks at a convergent plate margin, we drilled 13 holes altogether, achieving deep cored penetrations at two sites. Our aims were (1) to delineate the lateral and vertical variability in mineralisation and alteration patterns below the PACMANUS hydrothermal site near the 1650-1700 m-deep crest of Pual Ridge in the eastern Manus back-arc basin, so as to understand links between volcanological, structural and hydrothermal phenomena, and (2) to establish the nature and extent of microbial activity within the system. Technological innovations vital to success included our precise location of holes on small targets with drill-stem video, the use of a new hard-rock re-entry strategy, and deployment of casing with a new hammer drill. Other technical achievements were the first ODP application of an advanced diamond coring system, and the first direct comparison in a hardrock environment between structural images obtained by wireline methods and by logging-while-drilling (resistivity-at-bit).

Jan 1, 2002

By S. Rajendran

Gas Hydrates (Methane Hydrates) are solid, ice ? like substances composed of water and natural gas. They occur naturally in areas of the world where methane and water can combine at appropriate conditions of temperature and pressure and are found in the ocean bottom sediments and in some permafrost areas. Besides temperature and pressure, factors like bathymetry, sediment thickness, sedimentation rates, and total organic carbon content (TOC) also control gas hydrate formation in the sea. The stability of gas hydrates depends on the critical high pressure ? low temperature combination (0-17 bars, 0-25ºC), which in turn dependent on the mix of gases from which the mineral is formed. As the critical parameters can be altered by deposition, erosion or slumping of sediments, formation or melting of ice cover, rise and fall of sea level and sudden temperature changes induced by tectonic activities, current flows or volcanisms, the gas hydrates tend to be very unstable. It is becoming increasingly evident that naturally occurring gas hydrates are significant component of the shallow geosphere and are of societal concern in at least three major ways: as an energy resource, a geologic hazard and a major contributor for climatic changes.

Jan 1, 2010

By Satya Nandan

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

By 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.