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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 S. Hölz, M. Jegen, K. Reeck, A. Haroon

Past investigations of seafloor massive sulfides (SMS) focused on actively forming sites. New technologies are needed to explore for SMS deposits which have finished their active phase and are possibly covered by sediments or lava. For this purpose the new marine transient electromagnetic (TEM) induction system MARTEMIS was developed by GEOMAR. The system was used for investigations in the Tyrrhenian Sea (Palinuro Seamount) and at the Mid-Atlantic Ridge (TAG area) and proved to be suitable for operations at shallow (~600m) and great water depths (~3600m) in steep and difficult terrain. Calibration measurements in the water column demonstrate that it is possible to acquire high quality data, which is fit to be evaluated in terms of inversions. However, these calibration measurements also demonstrated that great care has to be taken in the design of such an inductive coil system, because relatively small metal structures attached to the system may lead to significant static distortions in the measured transients. The interpretation of TEM data acquired at the Palinuro Seamount show a conductive layer in the vicinity of a previously drilled, buried SMS occurrence and serve as proof of principle of the system. Results also indicate that the conductive SMS unit is indeed a confined layer with limited thickness between 3 – 5m, which was not known from previous drilling. In a similar manner, results also hint at an unknown mineralization at depth in a second area of the Palinuro Seamount. Investigations by TEM measurements were accompanied by measurements of the ambient electric field (→ self-potential) and seafloor temperatures with a heatflow probe as well as direct sampling with a gravity corer. The areal coverage of measurements and sampling allow for a greatly enhanced view of the structure.

Jan 1, 2018

By U. Schwarz-Schampera, C. Rühlemann, H. -R. Kudrass

Within 2006 BGR will conclude a contract with the UN International Seabed Authority (ISA) for the exploration of polymetallic nodules. The contract covers an area in the Pacific nodule belt between the Clarion and Clipperton fracture zones, that which is about 75.000 km2 in size at water depths between 4200 and 5000 m (see Fig. 1). Up to now, 7 consortia or state parties have acquired similar exploration “licenses” for polymetallic nodules in the central Pacific Ocean and the Indian Ocean. These licenses of the UN authority are required according to the UN convention on the law of the sea (UNCLOS) as the areas of interest are located outside of national EEZs. The “licenses” then reserve exclusive rights to the applicant for a time span of about 15 years.

Aug 24, 2006

By Makoto Yuasa, Akira Usui, Shipboard Scientists of SIP Cruises, Atsushi Suzuki, Shingo Kato, Kyoko Yamaoka, Akira Nishimura, Kiyo Kisimoto, Katsuhiko Suzuki

"We report here on current topics of our project, based on the results of recent cruises and laboratory analysis, about the diversity of compositions and configurations of the hydrogenetic ferromanganese deposits in several Northwestern Pacific Seamounts. This recent research has discovered important aspects of these deposits regarding the mode of variation with water depth, topography and substrate geology, possible bacterial mediation, temporal variation with age in mineralogy, and major and minor element chemistry. All cruises and analysis have been supported by the facilities and staff of the Japan Agency of Marine-Earth Science and Technology (JAMSTEC), Japan Oil, Gas, and Metal resources Corporation (JOGMEC), Geological Survey of Japan, and Kochi Core Center (KCC) using a remotely operated vehicle (ROV), a monitored rock drilling system, dredges, and manned-submersibles in the NW Pacific seamounts,The results indicate that most of the rock outcrops on the slopes, shoulders, and much of flat tops are covered with maximum 10-cm thick crusts, but the thickness, metal content, and microstructural properties are not always uniform over the seamounts, but variable in space and time. The micro-stratigraphic description of whole-rock samples indicates a history of deposition and sedimentation, which control the diversity in bulk composition and abundance caused by the variable incorporation of iron-manganese precipitates into the deposits during variable environmental conditions. We conclude that hydrogenetic precipitation of iron-manganese oxide has taken place for more than 20 million years at a growth rate about 4-6 mm/my, in water depths below 1000m. The results indicate a fairly continuous and constant metal deposition since the middle Miocene age or older to the present. Our case study of geological sciences at a model seamount within the Japanese EEZ suggests that scientific knowledge is useful and essential in exploring mineral deposits, economic estimation, and designing systems, if supported by well-combined geological and oceanographic and biological research. The distribution map of ferromanganese deposits and geological map will be published soon in 2017 to be issued by the Geological Survey of Japan."

Jan 1, 2017

By Sven Petersen

In April 2010 three REMUS6000 series autonomous underwater vehicles (AUVs) have been used to simultaneously map large areas near the Mid-Atlantic Ridge (3°N) axis in water depths ranging from 1,000m to 4,000m. One vehicle was provided by the Leibniz-Institute for Marine Science, IFM-GEOMAR (Kiel, Germany) the other two were provided by the Waitt Institute for Discovery (La Jolla, USA) and managed by the Woods Hole Oceanographic Institute (USA). The REMUS6000 vehicles, manufactured by Hydroid Inc. (USA), are "cigar-shaped" vehicles (4m long and weighing approx. 900kg) and consist of a tapered forward section, a cylindrical midsection and a tapered tail section. An internal titanium strongback, which extends through much of the vehicle length, provides the structural integrity and acts as a mounting platform for syntactic foam, equipment housings, various sensors and release mechanisms. The AUVs can be used in various payload configurations such as multibeam bathymetry, electronic still camera, or subbottom profiler. For these missions the electronic still camera configurations was installed. An EDGETECH 2200M dual frequency (120/410 kHz) side scan sonar was used to map the seafloor, but other frequencies are readily available for more options in resolution and range. The 120 kHz side scan transmitter was used for most missions in order to map large areas (increased range) and to be able to fly at higher altitudes (between 70m and 90m) above the rough seabed encountered in this area. The maximum slant range was between 600m and 700m on both sides resulting in a swath width of up to 1.2 km. Line spacing ranged from nearly 1,000m in flat areas down to 400m in steep terrain. Side-scan mosaics were generated with a 1m resolution. Selected areas were targeted by the higher resolution 410 kHz transmitter as well as by bottom photographs flying as low as a few meters above the seabed. The vehicles navigated autonomously using a combination of inertial navigation (Kearfott T-24 or T-16 INS) and long baseline acoustic navigation by computing their range to two moored acoustic transponders. Working efficiently in this rough topography at speeds above 3 knots was only possible due to the obstacle avoidance capabilities of these AUVs.

Jan 1, 2011

By Masaru Nakamizu, Tetsuya Fujii, Tatsuo Saeki, Ken-ichi Yokoi

Methane hydrate, a solid compound formed from methane and water, occurs naturally in permafrost regions on-land and in deep continental slopes offshore and has been examined as future energy resources. The existence of methane hydrate in the eastern Nankai Trough region, offshore Japan, was confirmed by drilling the MITI well “Nankai Trough” in 1999. Aiming commercialization of methane hydrate production, the Research Consortium for Methane Hydrate Resources in Japan (MH21, core associations: JOGMEC[*1], AIST[*2] and ENNA[*3]) under METI [*4] has been executing geological and geophysical surveys around the eastern Nankai Trough since 2001 as a nation project.

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 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 Tetsuo Yamazaki

Manganese nodules, seafloor massive sulfides, and cobalt-rich manganese crusts in deep-sea areas have been considered as future metal sources (Mero, 1965; Halbach, 1982; Lenoble, 2000). Manganese nodules were the first recognized deep-sea mineral resource and many efforts concentrated on the R&D of mining systems (Welling, 1981; Herrouin et al., 1989; Yamada and Yamazaki, 1998) and assessment of environmental impacts (Burns et al., 1980; Foell et al., 1990; Yamazaki and Kajitani, 1999). No mining venture, however, has been active for this potential resource. The reason is that the rate of world economic growth has been slower than anticipated in 1960s. During the 10 year period of 1994-2003 (Fig. 1), on the other hand, there was about a 33% increase in the world copper demand. Of that increase, about 60% was consumed by China. Most of China?s increased copper demand took place over the final 4-5 years of that period. The growth is expected to continue for several years, and in 10 years or sooner the same situation is expected for India. Copper is the third metal in global demand, but its small abundance in the Earth?s crust is not well recognized (Table 1). From the production rate and the abundance, a copper shortage, or crisis, has a high probability than the other metals. Japan has no domestic copper resources and needs a counter measure for this potential coming copper shortage. Fortunately, Japan has a manganese nodule mining claim in the Clarion-Clipperton nodule field, Kuroko-type massive seafloor sulfide deposits in the Okinawa Trough and Izu-Ogasawara areas, and cobalt-rich manganese crusts around Okinotori-Shima and Marcus Islands. We need to re-evaluate their potential as copper resources and to realize their development.

Jan 1, 2005

By David G. Jones

Radiometric surveys of the beach and nearshore zone of the Dutch Frisian Islands have identified sands enriched in heavy minerals. The areas of heavy mineral concentration have been mapped in detail using a state of the art towed gamma-ray detector, which gives improved sensitivity through the use of new detector materials and improved data processing techniques. The detector provides continuous measurement of sea floor radioactivity (and of a number of other parameters) and can be used simultaneously with other survey techniques, such as echo sounding, sidescan sonar and shallow seismic profiling. It enables a rapid, and cost effective, assessment of the surface distribution of heavy minerals to be made. The heavy mineral suite includes magnetite, ilmenite, garnet, rutile and zircon. These minerals contain 1-3 orders of magnitude more U and Th, in terms of their activity concentrations, than the accompanying light minerals (mainly quartz). Since the heavy mineral composition of the sands appears to be relatively constant along the Dutch Frisian Island chain, the U and Th concentrations can be used to provide a quick estimate of the heavy mineral content. The sea floor radiometric measurements allow sediment sampling for more detailed analysis to be highly targetted. The zones of heavy mineral enrichment are generally sub-parallel to the coast and are usually confined to water depths of 5-10 m. There is a close correlation with sand bars on the shoreface, the highest radioactivity typically occurring just seaward of the crest of these features. As well as being used for heavy mineral exploration, similar radiometric methods can be applied to mineral processing. Gamma-ray detection systems can be used to provide rapid analysis in the process stream enabling on-line grade control and optimisation of processing, from excavation of mineral sands to the final products.

Jan 1, 1995

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 Carl H. Hobbs

The needs of the on-going basic maintenance operations and proposed enhancement and hurricane protection projects in the City of Virginia Beach exceed the capability land-slide sources of sand. Through the past several years our studies have concentrated on locating and defining suitable quantities of sand appropriate for use on the area's beaches and assessing some of the consequences of dredging in shallow offshore areas. By providing information concerning the geological setting of sand resources, the local wave climate, and benthic infauna, the overall research project has strengthened the knowledge and understanding of several facets of Virginia's inner continental shelf. We have identified three distinct settings for deposits of beach-quality sand, two of which (filled channels and surficial shoals) are distinguishable in relatively unprocessed sub-bottom profiles and cores. The third, a sand facies within a larger stratum, is discernable only with a suite of cores. Sandbridge Shoal, about 5 km offshore of the resort and residential community of Sandbridge appears to contain a substantial quantity of sand that could be exploited with comparatively few problems. It already is designated as the source of material for use in a shoreline protection protect for a federal facility. Fluvial(?) fill of a late Pleistocene channel lust offshore of the main, commercial, resort area may offer a proximal alternative to existing and proposed resources. Ongoing work to describe the local wave climate and the possible impacts of anthropogenic alterations of the bottom topography on wave transformation and studies of the biological community as it might be affected by dredging will help fill-out our series of studies. Prior to utilization of the resource additional work is needed to provide better definition of the limits and magnitude of the sand bodies. Finally decisions concerning the use of specific resources will have to include physical, biological, economic, technical, and social considerations.

Jan 1, 1996

By Akira Usui

Occurrence of hydrogenetic ferromanganese crusts has been well documented over inactive seamounts in the central and southern Pacific Ocean. It has been thus believed that the hydrogenetic crusts develop preferentially at water depths between about 800 to 2500 meters. In fact, according to the Manganese Crust Database (F. Manheim, 1988), only two occurrences are known at water depths below 5000 m out of 819 occurrences cited in the database. Unexpectedly, we found typical hydrogenetic ferromanganese crusts from deep-sea floors; 1) outcropping old volcanic basement over the Philippine Sea Plate (abandoned spreading centers and subducting old oceanic crusts) and 2) one from the slope of an abyssal hill in the Central Pacific Basin (Cretaceous deep-sea basin) at water depths ranging between 5200 to 6100 meters. We report their occurrences with submersible observations from Shinkai 6K, physical parameters (such as thickness of crusts about 2-4 cm in maximum), chemical composition, petrology of substrate, and results of Be-10 dating for some samples in comparison with typical Co-rich manganese crusts from the Central Pacific seamounts. The preliminary chemical and mineralogical analyses reveal that they are of typical hydrogenetic origin, and typical of iron-manganese oxide mineral, vernadite, slow and probably continuous growth, and lower content of Co than the Central Pacific seamount crusts. The occurrences and nature of the crusts indicate that deep-sea floors are also optimal for the growth of hydrogenetic crust even at 5000 m water depth or deeper, only if oxygenated deep waters are supplied and the sea-floor morphology keeps stable enough for significant geological time period. Additional details of chemical analyses will be prepared by November and to be shown in the conference.

Jan 1, 2001

By Cameron Rees

The University of New South Wales Mining Research Centre (UMRC) has a longstanding research reputation in mining research, with particular expertise in mining systems, mining geomechanics and excavation engineering. The UMRC is now focusing this expertise on the potential of mining Seafloor Massive Sulphides (SMS). The UMRC has initiated a three-year research project that will identify and examine the requirements to effectively and efficiently mine SMS deposits. The major aims of this project are: ? To develop an understanding of the geomechanical characteristics and local physical environmental conditions associated with a ?typical? SMS deposit. ? To develop and evaluate a range of both conventional and innovative excavation processes for mining SMS deposits, and define the engineering parameters required for each extraction option, and ? To identify the materials handling and lifting requirements of the ?mined? SMS material, and the possible integration of the lifting system with the excavation processes considered.

Jan 1, 2002

By Shinichi Takagawa

The deep sea hydrothermal deposits are one of the most prospecting resources, and various works to develop these mines are now underway. There are also various methods for the pre-site survey of the mines: acoustic survey, electro-magnetic survey, and others. However, as a precise method at the final survey, drilling/coring is indispensable to confirm the three-dimensional distribution and to grasp the dignity of the ores for the final decision of industrialization. This drilling/coring at the final survey is done at many points with distance of 15~25m between each point for on-land deposits. This means that 1km by 1km square area requires (1,000m/25m)2 ~ (1,000m/15m)2 = 1,600 ~ 4,500 holes. The drilling/coring depths will be around 30m or more for the hydrothermal deposits. This depth seems very shallow, but because the stratum is very brittle and is very difficult to core, the average core recovery ratio is around 50%, and 0% core recovery happens very often. Thus, the indispensable work of coring for grasping the dignity of ores is a very difficult work although the coring depth is shallow, and also the required number of holes is enormous. Conventional drilling/coring method on the ocean is to use drillship. However, the cost is very huge. Recently a new technique has come out which is to use remotely controlled drilling machine on seafloor. This machine seems to have a very good performance. However, it is reported that the available inclination of the seafloor where the machine sits on must be less than 15 degrees. The sea floor inclinations of active hydrothermal vents area are usually very steep and slopes of 45 degrees or more are prevailing and it seems very hard to carry out drilling/coring for the machine at these steep slopes, although it is impossible to mine the ore at these areas because the temperature is too high to work there. The inclination of the sea floor at the dead or paused hydrothermal vents area where ore recovery is possible may be not so steep, and the machine may work well. However, the required number of holes is still a very heavy burden. In order to solve these problems, the author proposes a new concept of drilling/coring system operated from a conventional research ship. This concept is still a desk plan, but the author wants to realize this system at any means.

Jan 1, 2011

By C. H. Hobbs

A recently completed series of projects funded by the Commonwealth of Virginia and the U.S. Minerals Management Service was designed to assess the distribution of heavy minerals on the inner continental shelf adjacent to Virginia. These projects indicate that a suite of minerals of both strategic and economic interest is present. Analysis of several hundred grab and core samples shows that zircon, monazite, and titanium minerals (ilmenite, rutile, and leucoxene) occur in quantities that probably warrant further study by the mineral industry. Furthermore, side-scan sonography and shallow seismic profiles have provided information on the thickness and areal extent of the mineral-bearing sands. Possible development of the resource is enhanced by a potential use of offshore sand for beach nourishment. The results of the preliminary studies have been presented in open-file publications and oral reports in order that the mineral industry might have an up to date basis upon which to consider more exploratory work. Much of the effort south of the mouth of Chesapeake Bay was made in cooperation with and enhanced by an independent study of sand resources for beach nourishment and other needs. Preliminary review of the quantitative analyses of the heavy-mineral content of several hundred samples demonstrates that the distribution of high concentrations is non-uniform. From core data, the greatest abundances of some economic heavy minerals (ilmenite, rutile, leucoxene, monazite, and

Jan 1, 1988

By Hunsoo Choi

Internal textures of manganese nodules from Clarion-Clipperton zone of northeastern Pacific Ocean are classified into five textural zones: columnar-textured layered zone, cuspate-textured layered zone, cuspate-textured massive zone, cuspate-textured porous zone and massive- textured massive zone. Vernadite is the main constituent mineral in the columnar- and cuspate-textured layered zone. Buserite sometimes occurs in the cuspate-textured layered zone. The cuspate-textured massive zone is mainly composed of buserite. Todorokite is also associated with buserite in the massive-textured porous zone, where cuspates and globes are partially replaced by massive texture. In the massive-textured massive zone, todorokite, buserite and birnessite occur together. The analyzed elements of all zones are also classified into four elemental groups by the cluster analysis of correlation coefficients: Mn group, Cu-Ni-Mg group, Fe group and Si group. Mn group consists of Mn and K. Cu-Ni-Mg group consists of Cu, Ni, Zn, Mg and/or Ca, Na. Fe group consists of Fe, Co, Ti and/or Ca, P. Si group consists of Si and Al. Each textural zone is composed of three or four elemental groups. These four elemental groups are correlated with mineral composition, such as, Mn group with todorokite, Cu-Ni-Mg group with buserite, Fe group with Co-bearing iron-oxyhydroxide minerals, and Si group with silicates.

Jan 1, 2002

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 Yanis Miezitis, Gerald Mueller, Timothy F. McConachy, Ronald G. Sait, Keith R. Porritt, William J. McKay

In November 2004, Australia lodged with the United Nations Commission on the Limits of the Continental Shelf possible new maritime boundaries in relation to Australia’s continental shelf extending beyond 200 nautical miles from the Territorial Sea Baseline (Colwell and Symonds, 2005). If agreed by the commission, just over half of Australia’s land mass will lie below the sea, and Australia will have one of the largest marine jurisdictions in the world (14.41 million km2). With this jurisdiction comes a responsibility to manage and sustain the marine environment (McConachy, 2006). Knowledge of minerals and their resource potential is part of this responsibility but is generally poorly known (McConachy, 2005).

Aug 24, 2006

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