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By Jan M. Peter

Many of the Pb-Zn massive sulfide deposits of the Bathurst area in northern New Brunswick, Canada, are intimately associated with laterally continuous iron formation (IF) (Figure 1). This IF is a fossil laminated, exhalative, chemical sediment. Together, the IF and the Brunswick #12, Brunswick #6, and Austin Brook deposits (rightmost discontinuous horizon on Figure 1) are collectively referred to as the "Brunswick Belt". To date we have only studied the Brunswick Belt and have not examined the horizon along which the QSR, CNE and Flat Landing Brook deposits lie. The Bathurst area is underlain by the Tetagouche Group (Figure 2), a Cambro(?)-Ordovician sequence of metasedimentary and bimodal metavolcanic rocks that was intruded by mafic to felsic plutons and subsequently deformed during the Taconic Orogeny. The stratigraphic sequence consists of shales and greywackes that are overlain by carbonaceous shales and felsic volcanic and volcaniclastic rocks; these are in turn overlain by mafic volcanic and sedimentary rocks. The massive sulfide deposits and IF occur within the upper portions of the felsic volcanic rocks in close association with carbnaceous metasedimentary footwall rocks (Figure 2).

Jan 1, 1993

By Robert G. Ditchburn, Cornel E. J. de Ronde, Bernard J. Barry

The age of mineralization, its mode of formation, the time elapsed to amass an economic deposit, its capacity for sustainable extraction and, ultimately, its grade and tonnage, are key aspects in the economic viability of volcanic massive sulphide (VMS) deposits (Ditchburn et al, 2004). Radiometric dating methods applied at GNS Science have been recently refined with the purpose of efficiently determining the ages of seafloor VMS mineralization along active intraoceanic arcs. These developments include: determining the longevity of seafloor hydrothermal systems, details of individual chimney and massive sulfide mound growth, and insights into deep-seated processes, such as the transfer of elements from magmas to their overlying hydrothermal systems. In our pursuit to better understand seafloor hydrothermal systems along intraoceanic arcs, we have thus far compiled age information for three volcanic centres of the Kermadec arc (South Pacific) and one of the Mariana arc (NW Pacific).

By T. Semkova, G. Cherkashov, V. Rashidov, L. Anikeeva, G. Gavrilenko, G. Glasby

The Kurile Arc consists of at least 100 submarine volcanoes and 5 submarine calderas located mainly in the rear arc (Figure 1). The arc is seismically very active, particularly in the south, and is characterized by extensive volcanism and hydrothermal activity. At least one subaerial volcano on the arc (Medvezhy located on Iturup island) has an extremely shallow magma chamber and is intensely active.

By Yoshio Masuda

Cobalt-rich crust in rich Co, Ni, Mm and Pt will be a potential resources for island country such as Republic. Marshall Islands. This study was conducted for Marshall Islands by the President Kabua?s request. It covers crust resources, CLB mining, processing, and economic estimation, and study concluded feasible veiw.

Jan 1, 1991

By G. McMurray

The release by the U.S. Department of the Interior (DOI) of a Draft Environmental Impact Statement (DEIS) for the leasing of polymetallic sulfide minerals on the Gorda Ridge in December 1983 resulted in strong negative public reactions. The fundamental issues affecting federal-state relations included the amount of state involvement in the planning process and the continuing question of consistency (sensu Coastal Zone Management Act). The specific issues raised included the authority of DOI to lease nonenergy minerals offshore, the economic and strategic rationale for the proposed lease, and the adequacy of the DEIS. The questions of DEIS adequacy arose in three major areas: the lack of evidence for the existence of polymetallic sulfides on the Gorda Ridge, the lack of sufficient baseline data, and the lack of a mining scenario from which to assess potential impacts. The joint Federal-State Technical Task Force was formed in February, 1984 as part of an initial agreement between the State of Oregon and the Department of the Interior to work cooperatively. Other points in the agreement were (1) a reduction of any future proposed lease area from 40 million acres to no more than 4 million acres; (2) indefinite postponement of the lease sale; (3) deletion of the nearshore portion of the possible lease area covering the physical continental shelf and slope; (4) a commitment of a "tiered" EIS process; and (5) sharing of non-proprietary data with the public.

Jan 1, 1985

By Stanley R. Riggs

Phosphate deposits on the southeastern U.S. coastal plain have long been the major force in world phosphate markets. World markets continue to grow, but the role of U.S. resources is rapidly declining. This situation results from a complex interaction of economic, political, and environmental factors. Causes for this ongoing erosion of the U. S. market include 1) escalating costs, 2) changes in land-use patterns, 3) environmental pressures oh conventional mining techniques; 4) exhaustion of shallow, high-grade resources in Florida, and 5) increased, low-cost production in other countries throughout the world. In fact, some agencies and commodity personnel predict that the U.S. will become a net phosphate importer early in the next century. If this projection is correct, the U.S. industry must look towards major changes in the near future in order to continue to compete in the world market. One possible change includes development and application of unconventional mining techniques to cheaply recover vast 'new' potential resources in areas with lower land-use pressures. These 'new' resources include 1) deep phosphorites within major sediment basins of the southeastern coastal plain and 2) subsurface phosphorites on the continental shelf and within the U.S. EEZ. These latter resources include extensive deposits in Onslow Bay, N.C.; broad regions offshore of Savannah, Ga. and Cape Canaveral, Fla.; and the central portion of the west Florida shelf. Little research and exploration has been

Jan 1, 1988

By S. Jeffress Williams

The topic area for this paper covers the United States portion of the northern Gulf of Mexico, extending from the Rio Grande delta east to the Florida peninsula. Declaration of an Exclusive Economic Zone in 1983 expanded Federal economic jurisdiction on the continental margins from 12 to 200 nautical miles seaward from the coast. The nation-wide area of the EEZ totals 3 million square nautical miles, with approximately 186 thousand square nautical miles in the Gulf of Mexico. In the Gulf, the continental shelf has an area of 81 thousand square nautical miles, extending to a depth of 600 ft. and having widths of 6 to 120 nautical miles. Specific areas on the shelf offer the greatest potential for containing aggregate and other hard mineral resources. The primary geomorphic features along the Gulf coast include: barrier islands, chenier plains, tidal inlets, bays and lagoons, estuaries, and deltaic headlands. These features are composed of terrigenous siliclastic sediments, except for the west Florida coast, south of 29°N latitude, which is dominated by carbonate sediments. On the shelf, the primary features are linear sand shoals and associated sand sheets, relict delta lobes and channels, and banks related to salt diapirs and coral reefs. The composition and distribution of sediments in these coastal and shelf features are determined by numerous geologic factors including: seabed topography; riverine sediment discharge; sediment dispersal patterns due to currents, waves, storms and tides; tectonics and subsidence; and repeated fluctuations in sea level.

Jan 1, 1986

By Charles L. Morgan

The Minerals Management Service of the U.S. Department of the Interior and the State of Hawaii Department of Planning and Economic Development are investigating the cobalt-rich ferromanganese oxide crust deposits found within the Exclusive Economic Zones (EEZ) of the Hawaiian Islands and Johnston Atoll. The objective of this investigation is to complete a preliminary resource assessment and an Environmental Impact Statement for potential leasing of mineral rights to these crusts. The results of this effort will be summarized and published in a Draft Environmental Impact Statement in March 1986. Three oceanographic cruises to deposit sites in the Hawaiian Islands EEZ were conducted by the University of Hawaii in 1984. As a result, data and sample analysis yielded the following resource estimates (in thousand tonnes): (1) total crusts - 378,500; (2) cobalt - 2,500; (3) manganese - 76,200; (4) iron - 59,700; and (5) nickel - 1,400. These estimates do not include key factors such as deposit continuity, recoverability, and environmental sensitivity. A preliminary attempt to quantify some of these factors for one particular deposit is in progress and will consist of detailed field studies followed by laboratory analysis. Similar evaluations of the Johnston Island EEZ have also begun and are based upon field work conducted by West German researchers and the U.S. Geological Survey. The Johnston Island EEZ appears to have crust resources about as large as those contained in the entire Hawaiian EEZ.

Jan 1, 1985

By Takafumi Kasaya, Katz Suzuki, Yoshifumi Kawada

"INTRODUCTIONThe area beneath the seafloor preserves valuable resources that are inevitable to sustain our industrial society. Hydrocarbon resources such as petroleum and natural gases are one of the representative examples, which have been mined over a century (Brandt et al. 1998). In addition, submarine resources such as methane hydrates, ferromanganese crusts, and metal deposits of hydrothermal origin have long been known (Rona 2003; Kvenvolden and Rogers 2005), although methods of their mining have not yet been developed. All of these resources are distributed heterogeneously, and various exploration techniques have been developed and examined. The Japan Agency for Marine-Earth Science and Technology (JAMSTEC) is conducting a project on the development of exploration methods of these unexploited resources (Urabe et al. 2015; also see http://www.jamstec.go.jp/sip/images/pamphlet_e.pdf). The present study particularly focuses on our attempt on the developing an exploration method of hydrothermal ore deposits.Seafloor hydrothermal ore deposits are associated with submarine volcanoes of mid-ocean ridges, hot spots, and island arcs, and back arcs (Hannington et al. 2010). Active hydrothermal systems discharging high-temperature fluids can be detected above the seafloor as anomalies of temperature, turbidity, and acoustic impedance (e.g. Kasaya et al. 2015). However, because of the temperature limitation of mining (Boschen et al. 2013), the target of mining may be extinct and probably buried. To explore buried hydrothermal ore deposits from the vast seafloor area, geophysical surveys that can obtain information below the seafloor must be required. Several techniques including magnetic, electrical, and gravitational methods have been developed (e.g. Jones 1999; Kowalczyk 2008). Although physical properties taken by these methods are sensitive to the presence of hydrothermal deposits, difficulties are sometimes encountered. For example, anomalies of magnetic susceptibility and electrical conductivity, which characterize the presence of ore deposits, may be found above non-hydrothermal bodies such as volcanic bodies and reservoirs of hydrothermal fluids (e.g. Honsho et al. 2016). Thus, combinations of multiple methods must be used to specify the existence of buried hydrothermal ore deposits"

Jan 1, 2017

By Thomas Pichler

In the past marine mining technology has focused on bulk mining of base metals from polymetallic massive sulfides. This has not been very successful because of the relatively low unit value of these metals and other reasons such as water depth, etc.. The process of gold enrichment in hydrothermal deposits is controlled through five different factors: (1) nature and source of the solution, (2) source of the gold, (3) a mechanism for mobilizing and transporting, (4) a mechanism for deposition, and (5) a mechanism to preserve the deposit. Gold has been identified in marine polymetallic massive sulfides from various locations on the ocean floor (e.g., spreading centers, seamounts) with contents ranging up to 5 ppm Au. This is within the current range of 1.0 to 7.0 ppm gold content which classifies gold ores. The gold appears to have been derived during hydrothermal alteration of the oceanic crust. Until the present there has been little attention to the possibility of mining gold or other precious metals in the marine environment. However, the magnitude of hydrothermal alteration (seawater can penetrates to a depth of 5 km into the oceanic crust) and primary gold contents of the rocks in the pathway of the fluid indicates that major gold deposits must have formed on or in the ocean floor, but they have not been found. To find a big deposit might only take an exploration model exclusively designed for gold exploration on the ocean floor.

Jan 1, 1993

By C. L. Mardock

The U. S. Bureau of Mines participated in a two-year joint State of Oregon/Department of Interior Placer Task Force study on the economic and environmental aspects of Oregon's marine placer deposits. The effort culminated in a research cruise off the southwest coast of Oregon to investigate the geological and biological characteristics of the continental shelf deposits. The Bureau's role was to collect and study the placer material off the continental shelf and to determine its strategic potential and significance. In-depth characterization of the sediments by optical and electron microscopy verify that the placer material from Cape Blanco contains up to 3 pct ilmenite, 0.5 pct chromite, and small amounts of zircon and gold. However, harsh sea conditions and equipment failures prevented sampling below a four-foot depth at the Cape Blanco site. Results to date indicate that the deposits sampled off the southwest coast of Oregon do not represent a significant source of strategic minerals. However, further study of the deeper sediments off Cape Blanco may uncover significant concentrations of chromite. This presentation encompasses the site geology, the geophysical and biological activities of the expedition, and the results of the Bureau's mineralogical and chemical investigation. The combined findings of the Bureau and other Task Force agencies have provided information needed to expand the country's limited knowledge of marine mineral resources and has assisted state and federal agencies in the formulation of offshore mineral policies.

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 G. Rehder, C. Hensen, P. Linke, J. Bialas, M. Haeckel, W. Weinrebe, K. Wallmann

Research on marine gas hydrate and the methane cycle has a tradition at IFM-GEOMAR. In summer 1996 during a cruise with RV SONNE offshore Oregon (USA) scientists of the former GEOMAR recovered the largest amount of gas hydrate from the seafloor. This discovery stimulated research on marine gas hydrates in Germany and induced funding of scientific programs such as LOTUS and OMEGA with numerous innovative technologies within the special program GEOTECHNOLOGIEN of BMBF and DFG. The primary objectives of ongoing and future research are to achieve a comprehensive knowledge of: • gas hydrate distribution and quantity; • variation and regulation of gas hydrate formation and dissociation as well as of the related fluid flow; • functioning of chemosynthetic communities in methane oxidation, carbonate precipitation and methanotrophy as biological barrier against methane emission and • delineating the escape routes of methane to the hydrosphere and atmosphere.

Aug 24, 2006

By M. Ye. Melnikov

The report is about oceanic ferromanganese crusts ? covers of iron and manganese hydroxides developed over an opened rock of seamounts and rises. Ore bed parameters of crusts are understandable as their thickness and content of main economic components ? manganese, cobalt and nickel. All known results of research activity on ferromanganese manganese crusts point to that crust are characterized by notable variability of thicknesses and composition. It is possible to separate few levels of variability. The most evident is the first level of parameters variability, which is manifested in various regions of the Ocean, and connected first of all, with an age of submarine mountains, a host objects for a crusts. It was proved by many authors, that most powerful crusts are connected with submarine mountains of Cretaceous age. [1]. Crust thickness at the Magellan Seamounts reaches, for example 12-15 cm, sometimes exceeds 20-22 cm. Thicknesses of Hawaii Archipelago or Tuamotu crusts in 3-4 times less. Biostratigraphy studies of crustal sections at the Magellan Seamounts already show, that its main part started to form in the Late Paleocene. Four layers with well expressed features in structure and composition of a layer are separated in the section. From foot to top: Late Paleocene ? Early Eocene layer I-1, Middle-Late-Eocene layer I-2, Miocene layer II and Pliocene ? Quaternary layer III. Relics of more ancient Campanian ? Maastrichtian ore layer [2, 4] were discovered. It is evident for example, that Oligocene mountains could not be a host for two lower layers in the crust section.

Jan 1, 2010

By M. Ye. Melnikov

The report is about oceanic ferromanganese crusts ? covers of iron and manganese hydroxides developed over an opened rock of seamounts and rises. Ore bed parameters of crusts are understandable as their thickness and content of main economic components ? manganese, cobalt and nickel. All known results of research activity on ferromanganese manganese crusts point to that crust are characterized by notable variability of thicknesses and composition. It is possible to separate few levels of variability. The most evident is the first level of parameters variability, which is manifested in various regions of the Ocean, and connected first of all, with an age of submarine mountains, a host objects for a crusts. It was proved by many authors, that most powerful crusts are connected with submarine mountains of Cretaceous age. [1]. Crust thickness at the Magellan Seamounts reaches, for example 12-15 cm, sometimes exceeds 20-22 cm. Thicknesses of Hawaii Archipelago or Tuamotu crusts in 3-4 times less. Biostratigraphy studies of crustal sections at the Magellan Seamounts already show, that its main part started to form in the Late Paleocene. Four layers with well expressed features in structure and composition of a layer are separated in the section. From foot to top: Late Paleocene ? Early Eocene layer I-1, Middle-Late-Eocene layer I-2, Miocene layer II and Pliocene ? Quaternary layer III. Relics of more ancient Campanian ? Maastrichtian ore layer [2, 4] were discovered. It is evident for example, that Oligocene mountains could not be a host for two lower layers in the crust section.

Jan 1, 2010

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 Tetsuo Yamazaki

The Kuroko-type seafloor massive sulfides (SMS) in the western Pacific have received much attention as sources for economic recovery of gold (Au), silver (Ag), copper (Cu), zinc (Zn), and lead (Pb). Since the end of the 1980s, the Kuroko-type SMS have been found in the back-arc basins and on oceanic island-arc areas. In Okinawa Trough (Halbach et al., 1989) and on the Izu-Ogasawara Arc (Iizasa et al., 1999) are the typical representatives in the Japan’s EEZ. They yield a higher concentration in Au and Ag than the SMS found in ocean ridge areas (Rona, 1985). Similar formation processes with the Kuroko ore deposits on-land in Japan have been expected and outlined by many researchers (Sillitoe, 1982; Scott, 1985). The higher Au and Ag contents have increased the chances for profitable mining operation, which is under consideration by a private company (Malnic, 2001). Information about the resource potential of the targeted Kuroko-type SMS deposit, such as the amount of SMS ore body, the inside structure, the mean metal yields, and the geographical details are necessary for a technical and economic validation analysis for the development. The Sunrise Deposit of Myojin Knoll on Izu-Ogasawara Arc in the Japan’s EEZ is selected as a target for the technical and economic validation analysis. The relatively higher amount of information on its resource potential is the reason why the deposit is selected.

Sep 24, 2006

By Georgy Cherkashov, Vladislav Kuznetsov

The presentation describes new data concerning the age of the Mid-Atlantic Ridge (MAR) hydrothermal fields. The collection of massive sulfides recovered from six hydrothermal fields has been dated using the 230Th/U method. The range of the data obtained is rather wide: from 2.2 up to 65.1 thousand years BP. Three stages of hydrothermal activity were detected for this 65 Kyr period of geological evolution: modern (0 -5), 20-25 and 58–65 thousand BP (Figure 1). This conclusion was confirmed by dating the associated metalliferous sediment layers which also indicate the hydrothermal events led to the formation of sulfide mineralization. There is a correlation between the age and size of massive sulfide deposits: older deposits are larger (Table 1). This and other applications of obtained data will be discussed in presentation.

Aug 24, 2006

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 B. Prause

Ferromanganese crust samples collected from Central Pacific sea-mount areas became of special interest after surprisingly high nobel metal contents have been analyzed. Hydrogenetic crust growth is controlled by the conditions of the oceanic water column. Thicker encrustations show two crust generations of different age ranges. The mean values of the chemical composition state that the older generation is richer in P, Ca, Ni, Cu, Zn, and Pt and depleted in Fe, Ti, Co, Al, and Si. The differences apparently indicate a distinct change of the geochemical environment. The Pt concentrations vary up to 1800 ppb and do not clearly correlate to one of the other metals. This might indicate a bond of multiple nature. Several mechanisms have been proposed to explain the Pt concentrations in ferromanganese samples. Our models consider seawater and cosmic spherules as responsible Pt sources. In seawater the main species of dissolved Pt probably exist as the doubly negatively charged tetrachloro-complex. A precipitation of Pt in seawater may take place if the chloro-complex is decomposed by reduction of pt2+ to pt0. On the other hand, the Mn02 precipitation is caused by an oxidation of Mn2+ which is supplied from the oxygen-minimum zone. The large activation energy needed for the oxidation of divalent ~n" in solution has been recognised, and the resulting slowness in the formation of Mn(V1)-oxihydrate sug

Jan 1, 1989