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By Irina A. Pulyaeva

Hydrogenetic Fe-Mn crusts play an important role in marine mineral-deposit research because of their widespread occurrence and high concentrations of valuable and rare metals. Most Fe-Mn crust deposits occur on the tens of thousands of seamounts found in the global ocean as well as on ridges and plateaus. Because of these circumstances, it is essential to clarify a number of outstanding issues with regard to Fe-Mn crust history and development, including controls on metal sources and concentrations. The first-order characteristics of Fe-Mn crusts as potential ore deposits include concentrations of metals (grade) and the thickness of crusts (tonnage), which vary depending on Fe-Mn crust structure and texture. Data on the structure, composition, age, and deposit characteristics will help define which factors are key for the creation of mineral accumulation and which combination of factors leads to the formation of potentially economic concentrations of metals. In this paper, we address the structure and characteristics of Fe-Mn crust stratigraphic sections collected from Central and Western Pacific seamounts. We describe the changes in mineralogical and chemical compositions of crust layers of different ages, the occurrence and regional distribution of these layers that correlate regionally, and reconstruct the paleoceanographic conditions that influenced crust growth.

Jan 1, 2010

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character, morphology, texture, composition, and other seafloor properties are not available for some regions, are out of date and not inclusive of the massive data collected during the past several decades, and are not in GIS-based digital formats.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 Michael R. Gipp

Marine Mining Inc. is currently exploring for marine alluvial gold and diamonds on a prospecting licence over a concession that covers 10,000 km2 of the continental shelf of Ghana. The boundaries of the concession extend from 0 30'W to 2 40'W, and between the shoreline and approximately the continental shelf edge north of 4 30'N. This concession extends from Kikam Beach in the west, to Senya Beraku in the east, a distance of approximately 240 km, and seaward an average of about 40 km. The concession is entirely underwater, with the exception of the estuaries of the Ankobra and Pra Rivers. Ghana has been a large source of alluvial gold, with historical production exceeding 25 million ounces. Southwestern Ghana is characterized by Precambrian rocks, which have been folded into a number of NE-SW trending synclines and anticlines. The most significant feature of the Birimian rocks is the presence of evenly spaced gold-bearing greenstone belts. They are 10-15 km wide, separated by about 90 km, separate basins filled by folded metasediments and granitoids. The rivers that enter the concession drain most of the exposed gold-bearing belts of Ghana. Given that approximately 2 km of erosion has taken place since the Mesozoic, and that gold mines on these belts boast proven reserves of over 55 million ounces, it is likely that large amounts of gold have been eroded out and carried to the sea. Coastal fractures, related to Precambrian structures reactivated during Mesozoic rifting, are responsible for the physiography of the coastal area, which consists of high-relief horsts separated by grabens that have been occupied and infilled by rivers or by finer sediments during times of elevated sea level. These fractures were loci of gold mineralization during the Precambrian, and are the source of alluvial gold in rivers confined by them.

Jan 1, 1998

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 Marlene Olivares Cruz

The particles that make up the deep-sea sediments have two main sources: 1) those that are created in situ from dissolved components and 2) those that are washed into the ocean in solid phases from the continents, atmosphere, space and interior of the Earth. Many particles as they sink through the water column reaches the seabed and are known as pelagic sediments with terrigenous, biogenic, authigenic, and cosmogenic components. Among the minerals found in the terrigenous fraction of pelagic sediments are quartz, clay minerals, feldspar, micas, ferromagnesians, and the biogenic fraction with remains of siliceous organisms, such as, radiolarian and diatoms. The chemical nature of marine sediments is controlled by the contribution of particulate matter derived from various sources with varying compositions for the fixing of elements during deposition and the compositional changes carried out within the sediments during diagenesis. In the last decade there have been several studies on the mineralogical composition of seabed sediments, suspended particulate materials and cores, together with paleontological and geochemical data are used for paleoclimatic and paleoenvironmental reconstructions, analyze changes in sea level, stratigraphic correlations and identify past and present sources of sediment and terrigenous input pathways and to describe the current ocean mass (Martins et al., 2001, Oliveira et al., 1998). There is also a scientific and economic interest in the authigenic fraction of pelagic sediments formed from other materials for polymetallic nodules. The study of sediments associated with polymetallic nodules helps to know the genesis, evolution and occurrence of these deposits (De Koven et al., 2003, Dubinin et al., 2008).

Jan 1, 2011

By Carl H. Hobbs

The beach at the resort city of Virginia Beach, Virginia has been and increasingly will be dependent upon artificial nourishment for maintenance and for hurricane protection. Both existing base-level maintenance operations and planned substantial enhancement programs out strip the capabilities of traditional terrestrial resources to provide the required quantities of sand. Our research program, an amalgam of projects from several funding sources, has located and defined suitable quantities of beach quality sand for use on the city's beaches. The work also has furthered our understanding of the region's Quaternary history. Initially, reconnaissance level, high-resolution, sub-bottom profiles and surficial grab samples taken on the basis of sub- marine geomorphology identified two geographically and geologically separate areas worthy of further exploration. Further profiling supplemented with some cores further defined the potential sand reserves. The Sandbridge Shoal site is a large and discrete Holocene sandbody atop late Pleistocene strata. The sands in region offshore of the commercial area known as the Resort Strip appear to be recent fill within fluvial(?) channels cut into the older subsurface. Each of these resources is within roughly 5 km of major sites targeted for beach nourishment and/or hurricane protection and contains sand with appropriate geotechnical properties. Ongoing work will better define the dimensions and limits of the sand bodies and provide data to enable determinations to be made concerning exploitation. Ultimately decisions concerning the overall beach enhancement-hurricane protection projects will involve economic, environmental, technical, and social considerations.

Jan 1, 1995

By S. W. Chang, James R. Hein, S-R. Lee, A. Zondervan, H. Choi

"Nine Fe-Mn nodules from the extensive nodule field in the east of Campbell Plateau of southwest Pacific Ocean beneath the Deep Western Boundary Current (DWBC) and Antarctic Circumpolar Current (ACC) were analyzed for the 10Be/9Be dating by AMS (Accelerator Mass Spectroscopy) at IGNS, New Zealand.Several types of nodule morphology were identified including distinctive discoidal forms with overgrowths resulting possibly from overcrowding and partial sediment burial. Five principal nodule facies were also recognized by location and occurrence (Fig. 1) (Wright et al., 2005). Fe-Mn nodules show various concentric internal growth textures, such as, cuspates, large parabolic cuspates, pseudo-columnar, columnar, globular, and laminated, which vary even in a nodule with hydrogenetic, early diagenetic, or mixed origin. Each texture shows micro-textural varieties and different mineralogy and/or chemistry. The genesis of each internal texture was indicated by the REE patterns, the mineralogy of Mnoxides, and the Mn/Fe ratios."

Jan 1, 2017

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 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 Alexander Malahoff

Accumulation of cobalt -rich ferromanganese crusts on Pacific seamounts located off-ridge in the Hawaiian EEZ, represents a complex process that involves geologic aging of the seamounts, geographic transportation- of the seamounts on the Pacific plate during the past 80 million years, and geochemical history of the oceans for that period. A comparative study of the building and erosion processes of the young Loihi Submarine Volcano, located south of the Island of Hawaii , and the 80 million year old Cross Seamount, located west of Hawaii , shows that both edifices show wide armchair-shaped talus chutes and intervening ridges of exposed dikes. The similarity between the observed mass wasting process on Loihi and Cross suggests that the slopes of submarine volcanoes are geologically unstable from the time of their origin on the seafloor through their entire geological history. The slopes of Cross are covered by coalesced ferromanganese crust covered talus, steep exposed dike faces, and crust covered dike ridges. A study of the stratigraphy of the crusts shows a range of thicknesses and number of unconformities present. The thickest crusts, up to 8 centimeters, are found preserved within the larger coalesced slabs along the shallower slopes of the talus chutes and along the crests of the ridges between water depths of 400 and 1800 meters. The platinum content was used in stratigraphic correlation between the crusts in the coalesced slabs and those collected from ridges with the PISCES V submersible. In the samples studied, the highest platinum content of 0.7 ppm

Jan 1, 1991

By Akira Usui, James R. Hein, Rachel Dunham

Ferromanganese crusts are found on most hard-rock substrates in the deep ocean (800-3,000 m). Their distributions on seamounts are complex and controlled by a wide-variety of factors including seamount morphology, current patterns, mass wasting, substrate rock type and age, subsidence history, and others. However, the development of this potential resource ultimately depends on this distribution, as well as on the small-scale topography, grade, and tonnage. The parameters that will ultimately be used to define a mine site are unknown, but reasonable assumptions based on 25 years of data collection can be used to bracket likely permissive characteristics.

By Andreas Kaede

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

Jan 1, 2018

By Peter B. Hale

Canada has a long history of marine-related industry and onshore mining. Even so, commercial interest in marine mining, excluding seawater mineral extraction and offshore extensions of hardrock deposits such as iron and coal, has been sporadic; despite the fact that shelf mineral deposits supply a significant proportion of the national market requirements for many countries. Several factors have accounted for this including: a relative abundance of onland mineral desposits; the fact that onland deposits can be mined using conventional technology; and, a general lack of knowledge and public awareness as to Canadian offshore non-fuel mineral resource potential. In the mid-1970s the Department of Energy, Mines & Resources formed the Departmental Coordinating Committee on Ocean Mining. The Committee addressed the question of shelf non-fuel mineral resource potential and concluded that, while several reports had raised the possibilty of this alternative source, there had not been a systematic evaluation of the resource base. This led to the formation of a Shelf Working Group, whose task it was to outline and implement a departmental program to advance our knowledge of shelf resource potential. A methodology was devised that utilized existing geoscientific and hydrographic

Jan 1, 1985

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 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 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 Subramanian Rajendran

Placer minerals are one of the rich natural resources readily made available primarily and broadly in the form of inland placers, beach placers and offshore placers. The exploitation of placer minerals goes back in the history for a period of time immemorial in the form of alluvial placer mining. In India only 35% of coast has been scanned for beach placer minerals. The buried inland placers and offshore placers have not been given due attention. Integrated management and sustainable development of coastal and Open Ocean including the EEZ are of great importance to us. Judicious exploitation of non-renewable mineral resources plays an increasingly important role with regard to future economic and social development. This calls for newer techniques for exploring and analyzing more the seafloor. Though India could remain in the placer mining for the last four decades through the establishment of the Indian Rare Earth in both east and west coasts, the lack of necessary dynamism to expand such industry and catch the world market points out a significant setback. It is highly essential to establish the major trends of paleo-beaches, since some of them are definite to contain highly rich heavy mineral placers comparable to the one being mined by beach scraping. Placer deposits of heavy minerals occur in discontinuous patches on the beaches along the West Coast of India. In recent years the National Institute of Oceanography, India and the Geological Survey of India attempted to invest on nearshore placer exploration by applying the integrated survey techniques.

Jan 1, 2001

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 Michael J. Cruickshank

Marine minerals are more than an academic curiosity as they represent the most significant global source of mineral materials for economically and ecologically sustainable development for the future. Minerals research is traditionally carried out by industry and thus, in the United States at least, applied research in marine minerals may not get the share of government funding or attention that more exotic programs for space exploration or future global disasters engender. Two recent events have significantly changed the status of marine minerals. Discoveries made in the last thirty five years indicate that the potential for mineral occurrences in the oceans and seabeds, area for area, is as high as for terrestrial lands. On this basis the global mineral resource base has been recently increased by a factor of four of which three quarters is underwater. The recently enacted Law of the Sea has mandated what is probably the most far reaching re-distribution of natural resources in human history, and has resulted in a peaceful subdivision of seabed jurisdictions between the coastal nations of the world which should significantly affect future mineral markets and the balance of economic powers. Significant applied research efforts are ongoing for marine minerals as an adjunct to commercial production in southern Africa for diamonds; and in many other parts of the world for sands for beach and coastal protection. Forward planing, including research and development activities focussed on future commercial production of metalliferous oxides, continues in Korea, China, Japan, India, and with lesser activity, in the United States, United Kingdom, Germany and the CIS. Annual expenditures for this work amount to millions of dollars. In all cases the environmental aspects of commercial produc¬tion are a significant part of the research. Geologic studies on the occurence and distribution of metal sulfides at plate boundaries continue on a regional basis in the Pacific.

Jan 1, 1996

By James R. Hein

Manganese nodules from the Cook Islands (CI) Exclusive Economic Zone (EEZ) are compositionally different from other nodule fields. CI nodules have relatively high cobalt concentrations and low nickel, copper, and manganese concentrations (e.g. Hein and Petersen, 2013). This reflects the predominantly hydrogenetic (seawater source) origin for metals in the CI nodules versus dual seawater-pore water sources for most other nodules. The concentrations of many critical and strategic metals have not been previously analyzed for CI nodules, so comparisons with other nodule fields have been limited. To address this, we analyzed a set of nodules distributed throughout the CI EEZ for a complete set of 67 elements, including all of the metals that may be of economic interest, such as the rare earth elements (REEs), yttrium, tellurium, niobium, zirconium, tungsten, titanium, and others (see selected elements in Table 1). In addition, we recalculated the tonnages of nodules and contained metals from nodule abundance areas (in square kilometers) determined by GIS ArcMap calculations based on JICA/MMAJ (2001) nodule distributions. The nodule tonnage calculated and summed from each abundance sector yields a total inferred resource estimate of 9.66 billion tonnes of nodules covering an area of 1.21 million square kilometers; using a cut-off of 6 kilograms of nodules per square meter, yields a median tonnage of 8.59 billion tonnes of nodules covering 687,647 square kilometers (Table 2).

Sep 14, 2011