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By A. M. Olivarez

The elucidation of the theory of plate tectonics has provided a conceptual framework for understanding the formation and distribution of different types of ore deposits. For example, we now recognize that certain kinds of mineral deposits are generally associated with a particular type of plate boundary (i.e., massive sulfides often occur along divergent plate boundaries, whereas porphyry copper deposits are typically found along convergent boundaries). During certain geologic time periods, plate reorganization events have changed the relative proportion of different types of plate boundaries. Corresponding changes have been observed in the abundance and distribution of ores deposited during these times. The present study examines the temporal aspects of this relationship; i.e., do plate reorganization events play an active or passive role in ore formation? In other words, do plate reorganizations simply provide a more favorable tectonic setting in which ore formation can occur over significant time periods, or are they directly linked to the mineralization process? We have examined this question by comparing regional tectonic histories with the ages of known massive sulfide and porphyry copper deposits. Because these deposits, in particular massive sulfides, form as a result of hydrothermal activity, we have also compared regional tectonic histories with proxy indicators of this process in the marine sedimentary record. These indicators include increased mass accumulation rates of Ca, Fe, Mn, and opal, characteristic changes in the Sr/Ca and Mg/Ca ratios of biogenous carbonates, and shoaling of the carbonate compenstion

Jan 1, 1988

By John W. Padan

What is known about manganese nodules and their potential commercial recovery is outlined in terms of economics, legal rights, environmental impacts, and mineral genesis. As a result of 20 years of accomplishments it is clear that nodules comprise a real resource, and that they can be collected in water depths up to 5000 m, for brief periods, and raised to a surface vessel at rates of production appropriate for scale model systems. Based upon information in the public domain at present there is more confidence in the nature and magnitude of the resource than in the ability to recover nodules commercially. A review of the literature suggests that the metallurgical processing of manganese nodules is technically feasible and that the associated costs are well predictable. What is less clear is the market outlook for the products. All "overlapping claim" conflicts have been resolved. Therefore, parties with a historic interest in nodule mining appear now to have the right to mine in the future, assuming they properly complete whatever exploration license obligations they may have.

Jan 1, 1989

By Benjamin W. Haynes

The Federal government has a lengthy history in supporting and conducting research in the ocean mining and minerals field. The Federal effort has been and is currently focused primarily in four agencies: the National Oceanic and Atmospheric Administration (NOAA) within the Department of Commerce, and the Geological Survey (USGS), the Bureau of Mines (BuMines), and more recently the Minerals Management Service (MMS) within the Department of the Interior. While NOAA and the USGS have played dominant roles in mapping and geologic studies, and the MMS has recently provided funding for several task force studies within the Exclusive Economic Zone (EEZ) , the Bureau of Mines has conducted research in mining technology, minerals processing, resource definition, and economic evaluation of minerals from the seabed for over 20 years. These studies have yielded considerable minerals information regarding manganese nodules and crusts, placers, mineral sands, phosphorites, and sulfides. This paper reviews the past achievements in ocean mining and minerals programs starting in the late 1960's, describes current research and information efforts, and presents an outlook for Bureau of Mines research and information gathering efforts. Specific topics

Jan 1, 1989

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 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 Robert M. Owen

The rare earth elements (REE1s; atomic number 57 -71) exhibit a coherent chemistry, are widespread in nature, and tend to occur in characteristic concentrations in different geochemical phases. Because of their predictable chemistry, the REE's-are highly useful as indicators or tracers of geochemical processes, and are often used as such in investigations of the genesis of terrestrial ore deposits. However, analogous applications of the REE's to the study of marine mineral deposits have been constrained by our limited understanding of the marine geochemical cycle of these elements. For example, a continuing area of uncertainty in this regard involves the so-called "REE Mass Balance Problem." This problem refers to the fact that detailed geochemical mass balance calculations typically predict a significant imbalance for the REE's; i.e., the calculations predict that REE removal rates from seawater are 11-18 times greater than their input rates. Yet all other chemical considerations indicate that the REE budget should be roughly in balance. Recent studies at The University of Michigan suggest the solution to this problem lies in understanding the the role of seafloor hydrothermal activity in the marine budget of the REE's. Geochemical analyses of hydrothermal sediments from two Pacific sites (East pacific Rise at 19°s and the Southern Juan de Fuca Ridge at 45°N) clearly show that the REE component of hydrothermal sediments is primarily acquired via scavenging from seawater. Iron oxyhydroxides, which form as precipitates when hydrothermal solutions are debouched onto the seafloor, are the active scavenging agent. Although the REE content of hydrothermal sediments generally increases with increasing distance from the rise crest, this increase is especially pronounced for sediments deposited below the lysocline,

Jan 1, 1989

By E. Moriguchi, K. Tamaki, A. Okuda, K. Iizasa, C. Honsho

The northern Izu-Ogasawara Arc is characterized by an abundant distribution of submarine calderas along the volcanic front to the back-arc rift zones. In many of these calderas hydrothermal activities are observed. Among these calderas, hydrothermal ore deposits with economically feasible quality and amounts are hosted at two calderas, the Myojin Knoll Caldera and Beyonnaise Knoll Caldera. We conducted two research cruises in 2005 and 2006 to investigate further hydrothermal activities and ore deposits in these calderas and to complete the geological and geophysical mapping in the area. We discovered a strong signature of hydrothermal activity in the Myojin-sho Caldera using AUV capabilities. Newly obtained geological and geophysical data clarified the relationship between back-arc rifting tectonics and hydrothermal activities in the area. Five calderas (two of them newly found) and numerous (>200) volcanoes are mapped in the area. Complete SeaBeam coverage showed a distinct feature of the back-arc rifting activity and its relationship to the submarine calderas on the volcanic front. The back-arc rift zones composed of four segments separated by E-W trending volcanic ridges. Three of the calderas are located in the rift zone and are heavily deformed by the rift normal faulting that typically trend NNW-SSE. As the Beyonnaise Caldera is located in a swarm of faulting zones at the eastern end of the back-arc rift, the formation of the hydrothermal ore deposits found in the Beyonnaise Caldera are apparently affected by these faulting activities. Newly found submarine calderas are located in the rifting zone and are heavily faulted.

Sep 24, 2006

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 Sally Philpot, Siân E. Boyd, Hubert L. Rees, Emma Bee, Carla Houghton, Ceri James, Silvana N. R. Birchenough, S. Limpenny David, A. Coggan1 Roger, Koen Vanstaen

Every year approximately 22 million tonnes of marine sand and gravel are dredged form British waters. The eastern English Channel (EEC) contains substantial reserves, a proportion of which have been identified by the aggregates industry for potential future exploitation. The main aim of this study is to produce broadscale marine habitat maps of the EEC area. The UK aggregates industry has formed a consortium of representatives (the eastern English Channel Association), and have sponsored an initial baseline survey and follow-up sampling programmes as part of a Regional Environmental Assessment (REA) covering a patchwork of aggregate prospecting areas. To complement this effort, a large-scale geophysical survey was conducted in 2005 to place the REA in a wider spatial context and, thereby, to help assess the environmental significance of any future impacts arising from commercial aggregate extraction over the broader region of the EEC.

Sep 24, 2006

By I. Yu. Melekestseva, V. V. Zaykov

Paleooceanic structures of the Urals fold belt contain different volcanic-hosted massive sulfide deposits of the Urals, Kuroko and Cyprus types [Prokin, Buslaev, 1999]. Small Cobearing massive sulfide deposits, as Ishkinino, Ivanovka and Dergamysh, associated with ultramafites of the Main Urals fault, are less known. Interest to them had arisen after discoveries of the modern “black smokers” associated with ultramafic rocks of the Middle-Atlantic Ridge (MAR). Ores of the Urals deposits are enriched in Co (0.3 %) and Ni (0.6 %) that are concentrated in Co-Ni-Fe-sulfides, sulfarsenides, and arsenides. Ores also contain the increased gold contents – 3–6 ppm and up to 16 ppm in those saturated with As-bearing minerals. The aim of the paper is a comparison of precious metal mineralization in ores from the Paleozoic and modern ultramafic-hosted massive sulfides.

Aug 24, 2006

By Robert R. Tarver

A long history of gold production at Nome, Alaska has resulted in long term interest in the nearshore environment as a production target. Mining by Western Gold Exploration and Mining Company offshore of Nome yielded approximately 100,000 troy ounces of gold in the period 1986 through 1990. This study was designed to determine the relationship between heavy minerals, sediments, and gold concentrations which occur in the upper meter of sediment offshore of Nome. Standard procedures were implemented for grain size analysis, heavy mineral separations, and heavy mineral frequency determination.

Jan 1, 1991

By Irina A. Pulyaeva

Hydrogenetic Fe-Mn crusts are ubiquitous in the ocean basins and play an important role in marine mineral-deposit research because of their widespread occurrence and high concentrations of valuable and rare metals. Directed research, which started in the last quarter of the 20th century, has provided significant results, with substantial amounts of data produced on Fe-Mn crusts structure, composition, and distribution in the global ocean. Detailed study of several seamounts has given confidence about the scale of Fe-Mn crust development and their characteristics. Now, commercial interests gain more and more attention. However, at the same time some theoretical questions related to Fe-Mn crust history including controls on metal sources and concentrations have not yet been answered. Here, we present the overview of age, composition, distribution, and geological setting of hydrogenetic Fe-Mn crusts from Pacific and Atlantic seamounts and discuss the geological evolution and conditions that led to the formation of potentially economic concentrations of metals. The age, composition, and distribution of Fe-Mn crusts in the Atlantic and Pacific oceans were determined by using a Fe-Mn deposits database compiled from our original data, published papers, published databases, and other international sources. Comparative analysis of Fe-Mn deposits from the Atlantic and Pacific oceans shows that there are similarities in basic characteristics of crust formation in both oceans. Simultaneously, there are significant differences in the scale of Fe-Mn crust distribution and composition that can be explained by differences in geological settings and characteristics of the deposition environment.

Jan 1, 2011

By Caleen E. Kilby

A program of surveying and studying the surficial sediments of northern Juan de Fuca Strait was undertaken between 1988 and 199 1. Detrital sediments were mapped from the intertidal zone down to 100 m depth along the slopes of a series of shallow coastal marine terraces. The sand heavy mineral content was examined over this region and sediment geochemistry and assays were performed on selected samples both offshore and from beaches along the coast. The coastline of southwestern Vancouver Island has numerous streams, with a history of small Au placer extraction, which empty into the strait to the south. Only very minor evidence of this was seen in values from isolated locales. However, one beach presented a remarkably different mineralogy and geochemistry from the remainder of the coastline. From the beach to 800 meters offshore heavy mineral contents were greatly elevated and Ti values were as high as 1.4% of the sand fraction. Minerals were relatively fresh and angular, with mineral percents distinctly different than those found elsewhere along this coastline. No stream of substantial size crosses this largely sandy-gravel beach. A series of studies identified the source of this small marine placer as having its origins n the tailings from a submarine pipe broken short in the next bay. A Cu-Au mine 1.5 km upstream, closed by the mid 1970's, had processed its ore underground and piped the crushed tailings to the submarine discharge pipe. The crushed material has been transported and concentrated with the longshore current and been sorted by strong coastal swells. Ilmenite/titanomagnetite from the homblendized basalt of the mine is the source of the Ti enrichment.

Jan 1, 1994

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'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 Kokichi Iizasa

Modern Kuroko-type deposits have been much reported in submarine calderas and cauldrons in the EEZ of Japan since 1988. Some of them have been found based on heavy mineral analysis of sediments in which sulfide particles may be derived from hydrothermal sources in the ambient areas. From the end of August to early September 2007, in the middle Izu-Ogasawara arc south of Tokyo, ROV expeditions were carried out in submarine calderas in order to examine mineralogical features between intact heavy particles spouting out from sulfide chimneys and heavy minerals such as sulfides in sediments around sulfide mounds in Kuroko-type deposits, and to find more newly formed hydrothermal sulfide fields in those areas. Some preliminary results from the ROV expeditions are reported here.

Oct 15, 2007

By William C. Hirt

Column flotation is a promising technique for processing as-mined, cobalt-rich, ferromanganese crust to separate the valuable crust component from barren substrate-rock, either aboard ship or within the water column. Column flotation testing was carried out in a seawater medium using samples obtained from the U.S. Exclusive Economic Zone (EEZ) in the mid-Pacific Ocean near Johnston Atoll. The collector reagent was a mixture of diesel fuel, fatty acid, and sulfonate previously developed at the U.S. Bureau of Mines for crust flotation using conventional flotation cells. Results are dependent upon particle size and reagent dosage, especially *as these factors affect froth volume and stability. Column flotation results are compared with previous studies in conventional cells. An overview of how column flotation might be applied in an offshore mining and processing system is given.

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'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

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 Ian Selby

Recent offshore diamond exploration has been concentrated in the SW Joseph Bonaparte Gulf. I`IW Australia. Extensive high resolution seismic and sampling surveys have been carried out in Cambridge Gulf, offshore of the mouth of the OR River and other rivers of the region. Surface-tow boomer surveys have been correlated with sampling data from vibracores and a wide diameter (1m) airlift system, providing a geological framework for the area. Although large-scale bulk sampling has not been undertaken, there has been no reported recovery of diamonds since 1993. The geology and prospectivity of a range of potential diamond traps in high energy, fluvial and transgressive depositional settings has been assessed. Potentially diamondiferous targets include (i) a shoreline apron. (ii) fluvial/estuarine channel infills and terraces and (iii) ravinement surfaces.. Although there is evidence for a long history of fluvial development and sea level changes, the majority of the investigated traps represent the result of erosion and sedimentation during and following the last interglacial. Significant volumes of unconsolidated gravels and coarse-grained sands with occasional indurated layers are present, and are locally exposed at sea beet In place s thick successions (>5m) of fine-grained overburden overlie the coarse-grained sediments.

Jan 1, 1998

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