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By Lu Jun

Up to now, much data on marine minerals, as well as on marine geochemistry, have been accumulated. Modem computer databases provide optimum flexibility and power for manipulating these data. The best worldwide marine mineral database is currently the Marine Minerals Bibliography and Geochemical Data Base created by Carla Moore et al. at the National Geophysical Data Center in the United States. In fact, in the course of studying marine minerals and geochemistry we may collect not only digital-character type data but also graph and image (black-white, grey and color image) data types. For instance, correlation diagram between chemical compositions of minerals, spectroscopic graphs, (e.g. infrared spectra, Mossbauer spectra, etc.), grey or color images from both optical and electron micro- scopes (scanning or transmission electron microscopes) as well as seabed photographs. Charles L. Morgan et al. (1993) reported that 10,000 photographs and some video images of the seabed in the Clarion-Clipperton region of the northeastern tropical Pacific have been collected by the Ocean Minerals Company. If both graphic and analytical information were stored in a database, it would be very useful and convenient to marine geologists. This system would not only be able to search for all the data based on one parameter, but also for both size and composition distributions. If possible, geostatistical methods could be combined with fractal dimensional methods. Of course, this would require enormous efforts. Before multimedia technology emerged, it was very difficult to create image databases. The emergence of large-capacity compact discs, high-speed central processing units, and high-speed digital signal processing techniques makes it possible to establish multimedia database management systems (DBMS), image-text DBMS, that involves graphs, text, images, and sound. In order to store image fields in a DBMS, we have to take into account two problems: (1) image access format and (2) image compression code standard.

Jan 1, 1994

By Tatiana ?. Sedysheva, Vladimir V. Ivanov, Michail E. Melnikov, Irina A. Pulyaeva

"INTRODUCTIONHydrogenetic 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 [3, 4 - 8]. Now, commercial interests gain more and more attention. Mining systems are being developed which involve fragmentation of the crusts and their separation from the substrate. The effectiveness of such activities greatly depends on physico-mechanical characteristics of the crusts and rocks on which they form. This determines the importance of the engineering geological study of the objects.This article comprises the results of the engineering geological studies of the crusts samples (72 samples) and their underlying rock substrates (75 samples), which were carried out during the research cruises 6-06, 6-07, 6-08, 6-13 (2006-2013) on the Magellan Seamounts guyots in the Western part of the Pacific Ocean by the specialists of the State Scientific Centre Yuzhmorgeologia [10 - 13, 19, 20]. The authors of the article directly participated in the studies mentioned above.MethodsEngineering geological studies were carried out on board of the research vessel Gelendzhik and in the laboratories of NPA «Sevmorgeologiya». The studies involved the determination of the following parameters:"

Jan 1, 2017

By Richard T. Haworfh

The United Nations Convention on the Law of the Sea (UNCLOS) entered into force, for those nations who had ratified it, on November 16, 1994. The Convention deals with nearly every aspect of ocean affairs, including marine scientific research, fishing zones, freedom of the high seas, protection of the marine environment and deep seabed mining. Article 76 of the Convention defines edge of the continental shelf in a way that many earth scientists find bizarre. Out to this limit, a coastal state has sovereignty over the seabed and sub-seafloor resources. Beyond that limit, the key principle of UNCLOS, that "the resources of the deep seabed represent the common heritage of mankind and should be developed to benefit all nations" is invoked. Establishing that limit and managing development in the different areas of jurisdiction is no small task. Canada's continental shelf as defined by UNCLOS covers an area approximately equal to half the area of the Canadian land mass. Interpretation and application of the convention is therefore highly significant for Canada. For example, the sedimentary basin in which the offshore Hibernia oil field is found, extends beyond the 200 mile limit but lies predominantly within the limits of the (UNCLOS) continental shelf. Responsibility for development of inshore placer deposits rests firmly with the coastal state. However, development of deep sea mining, in which the international community plays a management role under UNCLOS, has raised many concerns. Of particular interest to Canada will be the application of the provisions of the convention to interest in the polymetallic sulfides sampled on the mid-ocean ridges such as the Juan da Fuca Ridge. A further complicating factor for Canada is management of fishing stocks. Canada has sought to resolve this "problem" through multilateral negotiations under the UN. Under its "Oceans Act," currently being debated by Parliament, Canada intends to become a world leader in oceans and marine resource management. Similar activity in most maritime nations is setting the stage for a revolution in the way in which use of the world's oceans is managed. Much of this revolution will be guided by UNCLOS. Coastal states that have ratified the convention have ten years in which to define the limits of their continental shelves the clock is already ticking for them! We have yet to see how their actions will guide, or be guided by, those who have not yet ratified. We also have yet to see how national legislation and aspirations will mesh with international conventions that were drawn up in a previous era of environmental standards. This is a time in which many questions have been raised and few firm answers received. However, we must ensure that everyone is aware of what is happening, with what potential consequences, in order that rational decisions can be made. Canada has taken a few small steps that it is happy to share with the world community.

Jan 1, 1996

By T. Yamazaki, R. Arai, N. Nakatani, K. Kuroda

"These 40 years, deep-sea mining for manganese nodules, cobalt-rich manganese crusts, and seafloor massive sulfides has been continuously business and R&D targets. The economy is the most important factor for realizing the venture. Some technological options to increase the economy of deep-sea mining are introduced. They are a mechanical lift, waste rejections on seafloor, a substrate recovery as byproduct, and a pulp lift. An example application of one of the options is economically examined. Not only the same type examinations but also some technological clarifications of the options in detail are necessary.BACKGROUNDManganese nodules (nodule), seafloor massive sulfides (SMS), and cobalt-rich manganese crusts (crust) have been well recognized as future metal sources these 40 years. Among them, the nodule was the first recognized ones. The mining technologies for the deep-sea mineral resources, therefore, have been mainly developed in the major R&D projects for the nodule.The mining systems considered were shuttle miner, continuous line bucket (CLB), and hydraulic dredge ones. The shuttle miner system studied by France was a kind of basic study for autonomous underwater vehicle. The CLB system was an effective approach for a small scale and less investment cost mining (Masuda and Cruickshank, 1995). However, both were considered not effective for a bulk scale production rate mining such as 1.5 million tons per year in dry weight. In the hydraulic dredge system, a steel-pipe and flexible-hose conduit for nodule transportation named “pipestring” and a hydraulic pumpup instrument for creation of upward water flow in the pipestring named “pump-lift” or “air-lift” were adapted and developed. Hence, the hydraulic dredge system became the main stream in the mining system."

Jan 1, 2017

By Hans Smit

The face of mining as we know is changing as mining companies all over the globe realize the reality of accessing the vast mineral wealth contained on, and under, our ocean floors. With some land based mineral deposits being fully exploited across the world, deep sea mining is set to revolutionize global approaches to the search for precious metals and other sought after minerals. Previously, the financial and technological implications of deep sea mining outweighed the benefits of access to the mineral rich deposits identified all around the world. The process of marine diamond mining off the west coast of southern Africa started in the late 1950s, and subsequently continued by De Beers to the present day, has proven to be an excellent proving ground for the development of technology and mining systems that ensure a sustainable and financially viable business.

Jan 1, 2011

By J. A. Jankowski

The situation in the raw material market has brought into consideration the commercial exploitation of the mineral deposits on the deep sea bed and in particular the manganese nodules. They occur generally in depths of 4000-5000 m, partially covered or buried in bottom sediments. The deposits and their potential recovery have been intensively explored and researched during the past twenty years (Bischoff 1979, Halbach 1988, Padan 1990). Although the present market situation limits the rentability of deep sea mining on an industrial scale, the mining technology is being further developed in many countries. The stagnation phase in the deep mining issue allows sufficient time for conducting research on the precautionary protection of the deep sea environment and for consultation in the development of technologies with the least possible impact on it. The subject has gained in importance since autumn 1994, when the United Nations International Law of the Sea was signed. This also regulates human activities in international waters from the environmental point of view. As fields tests have shown in the past, even with the most modern technologies, mining of the manganese nodules will inevitably be accompanied by a resuspension of some bottom sediments. The generated sediment plumes will be further transported with the ocean currents and in the worst case form stable turbidity layers in different depths (Ozturgut 1981a, Baturin 1991). One of the problems of the environmental impact assessment is the estimation of the plume persistence before it eventually dilutes to approximately the ambient concentration level or settles at the bottom (Lavelle 1981a, Lavelle 1981b, Lavelle 1982, Thiel 1991a, Thiel 1991b). The aim of the research is to develop a numerical sediment transport model in connection with potential manganese nodule mining in a reference area located in the southeastern equatorial Pacific Ocean off Peru (Peru Basin, Discol Experimental Area). In this region, a German mining claim is registered and interdisciplinary field works of the TUSCH (German: TiefseeUmweltSCHutz, deep sea environmental protection) research group are carried out in order to obtain the required scientific background for evaluating of the deep sea mining impacts and to provide the necessary supporting data for the modelling (Thiel 1991a, Thiel 1991h).

Jan 1, 1995

By Karsten Hagenah, Tor Jensen, Jens Laugesen, Øyvind Fjukmoen, Lucy Brooks

This paper describes operational environmental threshold levels for exploitation of mineral resources in the deep sea. Such criteria are needed to be able to monitor and control deep sea mining with respect to the stringent environmental requirements that are needed. It is recommended to use existing environmental threshold levels for comparable activities where such are existing. Fields of application are mainly but not exclusively seabed mining operation activities under the governance of the International Seabed Authority (ISA). The threshold levels and limits mentioned in this paper are proposed recommendations based on other activities than seabed mining but are a proven and accepted approach in other maritime industry activities. An example of such other activities with proven and accepted environmental threshold levels are Oil & Gas exploitation activities in the sea. Background The first exploitation of mineral resources is coming closer. At the moment regulations for exploitation for mineral resources in the Area are being developed by the International Seabed Authority (ISA). The ISA regulations will contain the framework related to environmental monitoring of exploitation. However, the regulations will not contain operational environmental threshold levels for the Contractor.

Jan 1, 2018

By Karsten Hagenah, Tor Jensen, Jens Laugesen, Øyvind Fjukmoen, Lucy Brooks

This paper discusses operational environmental threshold levels for exploitation of mineral resources in the deep sea. Such criteria are needed to be able to monitor and control deep sea mining with respect to the stringent environmental requirements that are needed. It is recommended to use existing environmental threshold levels for comparable underwater activities. Fields of application are mainly but not exclusively seabed mining operation activities under the governance of the International Seabed Authority (ISA). The threshold levels and limits mentioned in this paper are proposed recommendations based on other activities than seabed mining but are a proven and accepted approach in other maritime industry activities. An example of such other activities with proven and accepted environmental threshold levels are Oil & Gas exploitation activities in the sea. Background The first exploitation of mineral resources in international waters is coming closer. Presently regulations for exploitation for mineral resources in the Area are being developed by the International Seabed Authority (ISA). The ISA regulations will contain the framework related to environmental monitoring of exploitation. However, the regulations will not contain operational environmental threshold levels for the Contractor.

Jan 1, 2018

By Mark Vardy, Kate Dobson, Isobel Yeo, Paul Lusty, Bramley Murton

In response to anthropogenic climate change, the way in which we use and generate energy is changing. To facilitate these developments, it is essential that we increase and diversify the supply of ‘E-Tech’ elements essential for cleaner energy generation and more efficient usage. The vast majority of these materials (e.g. cobalt, lithium, niobium, platinum group metals, rare earth elements and indium) come almost exclusively from mining and new resources must be found and developed in order to secure supply and meet the demands of the future. Ferromanganese (FeMn) crusts are rich in cobalt, tellurium and rare earth metals, and are common on seafloor hard grounds at water depths over 1000 m. The mining of both FeMn crusts and nodules is potentially viable dependent of the balance of cobalt and nickle prices (Martino & Parson, 2012), however, crusts need to be at least 4 cm thick with cobalt contents of at least 0.8% (International Seabed Authority, 2008). The difficulty for those wishing to exploit these resources is firstly finding them, and secondly assessing their potential remotely. Such capability would not only save time and money, but also allow mining operations to be more focused, reducing needless destruction of seafloor habitats from exploratory mining or mining of noneconomically worthwhile deposits. In this contribution, we examine the distribution of crusts on a single Atlantic Gyot (Tropic Seamount), the morphology of FeMn crusts, their variable growth patterns and the characteristic geophysical response from crusts in various datasets, including ship based 60 m resolution multibeam and high resolution bathymetry, backscatter and sub-bottom profiler data acquired using an Autonomous Underwater Vehicle (AUV).

Jan 1, 2017

By Robert G. Paul

President Reagan's Exclusive Economic Zone (EEZ) Proclamation of March 10, 1983, extended United States ocean jurisdiction 200 nautical miles offshore our coastal states and territories. The accompanying policy statement noted that this action was a result of recently discovered deposits of polymetallic sulfides and cobalt-rich manganese crusts, which could be a major source of minerals important to the U.S. economy and security. Within these 3 billion acres of exclusive economic jurisdiction, the United States has sovereign rights to explore, develop, conserve, and manage the mineral and other natural resources of the seabed. The President has directed the Department of the Interior (DOI) to encourage exploration and production of minerals from this area. The DOI, through the Minerals Managment Service (MMS), is responding to this presidential directive by developing a leasing program for nonenergy minerals in the EEZ. The authority to develop this leasing program is the Outer Continental Shelf Lands Act of 1953, as amended in 1978, which authorizes the Secretary of the Interior to grant leases for oil, gas, sulfur, and other mineral resources on the Outer Continental Shelf (OCS). The Solicitor of D01 has determined that the definition of the OCS for legal purposes extends at least 200 nautical miles offshore of our coastal states to the EEZ boundary. Section 8 (k) of the Act allows the Secretary to lease minerals, other than oil, gas, and sulfur, on the basis of competitive bonus bidding and under such terms and conditions as he may prescribe at the time of offering the area for lease.

Jan 1, 1985

By Gérald Riverin

Over the past century, exploration methods for volcanogenic massive sulphide deposits have evolved in response to a decreasing number of discoveries made by traditional surface prospecting and by ground and airborne geophysics. Statistical trends support the concept that fewer and fewer outcropping and sub-cropping VMS discoveries will be made in the future. In turn, this creates new opportunities to develop more sophisticated exploration models and techniques to explore at greater depth and to make blind discoveries. Current exploration models include various combinations of geological, geochemical and geophysical criteria which have been based on the results of land-based VMS research. The role of seafloor research in the development of these models has so far been only of a subordinate nature, perhaps due to a lack of direct involvment of the exploration industry in the seafloor research, and vice-versa for the seafloor researchers in VMS exploration. Another contributing factor is that exploration relies on exploration criteria that result from detailed geological, geochemical and geophysical studies of both footwall and hanging wall rocks, studies that are not possible in modern sea floor environments. Nevertheless, seafoor research has contributed to our understanding of the growth of sulphide mounds, the mechanism of sulphide deposition and of the chemistry of fluids involved in VMS systems. In particular, the role of structure and of tectonic setting has been clarified through observation of active seafloor hydrothermal systems. In turn, observations made in land-based VMS research has helped seafloor researchers to focus on key issues which, will eventually contribute to improved exploration models.

Jan 1, 1998

By I. V. Kubrakova, O. A. Tyutyunnik, M. L. Getsina, A. M. Asavin

An analysis of noble metals (NM) in natural samples is most problematic. Determination of their traces in geochemical samples, in part, for the purpose of deposit evaluation, is a difficult analytical task. A number of international standard reference materials of rocks and ores, in which NM content is certified, is estimated at a half dozen. For example, in the International proficiency test for analytical geochemistry laboratories (GeoPT), which is held by the Department of Earth Sciences (The Open University, United Kingdom), the data for gold and platinum are observed very rarely, and the results obtained in different laboratories differ on 1-3 orders of magnitude. It is caused by low contents of NM in nature, by a variety of their complex and mineral species, as well as by a complicated matrix composition of platinum-containing objects. Among these objects are ferromanganese ores, enriched strongly with Fe, Mn, Ni, REEs - the elements hampering a precise determination of NM due to a complexity of instrumental inter-element correction. The absence of the reliable methods of NM determination in these ores drastically limits the possibility of deposit evaluation.

By James M. Franklin

Research on modern hydrothermal systems provides quantitative measures of the processes of formation of hydrothermal fluids and of precipitation mechanisms from them. Studies of ancient deposits provide new information regarding volcanological processes that are related to the deposits, as well as data on their spatial and temporal compositional variations. Mew exploration guidelines result from both aspects of research. The most fundamental requirement for large metalliferous hydrothermal systems is an abundant heat supply for the upper two kilometers of the crust. This heat may come from a focused heal source (shallow-level subvolcanic intrusion), but ambient heat also may have provided enough energy for the reactions necessary to effect leaching of metals, especially where heat flow is particularly high (i.e. very large or high-temperature magmatic source, such as ultramafic environments). For most VMS systems, the majority of the metals were derived through leaching from footwall strata; in addition interstratal fluids may enter subvolcanic intrusions during episodes of magma a chamber "cracking," engendering some '?magmatic" component in the hydrothermal system. Direct contributions of metalliferous magmatic fluid also may be significant from arc-related or back-arc felsic or alkalis systems. These latter contributions may form exceptionally high - grade portions in some deposits. Subvolcanic intrusions, which are excellent indicators of high heat flow and may have been the direct driving mechanisms for some stems undergo two stages of alteration: On intrusion emplacernent. fluids may rapidly enter and react with their mesostatic portions, evident in the sills in the Middle Valley. High temperature interactions caused albitization and destruction of oxides and sulfides, releasing metals. During terminal hydrothermal stages, the metalliferous fluid collapsed into the intrusions, forming disseminated and vein sulfides.

Jan 1, 1998

By S. C. W. de Jong, E. de Hoog, J. M. van Wijk, S. J. Dasselaar

Introduction Technology development for sustainable, safe, reliable and efficient mining of polymetallic nodules in the deep seas requires careful design, thorough understanding and integrated testing of all equipment, physical processes and (sub) systems involved (Dasselaar et al [1]). Proceeding from Vertical Transport System (VTS) experiments at IHC laboratory scale by Van Wijk [2], with typical system dimensions of several meters, to prototype or pilot scale testing with typical dimensions of several kilometers, is a giant leap. Naturally, intermediate steps are required in order to mitigate the possible risks in the full-scale system’s (physical) processes. Within the EU program Blue Mining (2014-2018), possibilities emerged for performing experiments at intermediate scale: the so-called medium-scale vertical slurry experiments. Near Freiberg, Germany, the village Halsbrücke possesses a 140 meter deep empty vertical mine shaft, perfectly suited for housing the test setup. For this purpose, a 318 meter long 145 mm pipeline circuit was constructed, including both a 130 meter high vertical riser and fall pipe section. A purpose-built sediment injection and separation system was deployed, including a 55 kW centrifugal pump. The riser section has been equipped with sensors capturing pressure, temperature, flow velocity, volumetric concentration and flow visualization. The planning, modification and construction of the test facility site itself is described by Müller et al [3]. The present paper describes the objectives, experimental program, equipment, and the preliminary results. Publications on in-depth results are foreseen in the (near) future.

Jan 1, 2018

By Raymond Kaufman

While there is no immediate worldwide shortage of hard minerals, the consumption of natural resources is constantly increasing, and there are ominous predictions of shortages to come. Means of meeting rapidly increasing demands are being implemented. These include such methods as exploration and discovery of new ore bodies, development of new mines, increasing production at existing mines, working or reopening known deposits of lower grade ore and tailings, recycling old materials, and developing more efficient and less wasteful processes to convert ores and metals into useful products. The United States, although itself mineral-rich, depends in large measure on imports for many key minerals and basic materials derived therefrom. According to the Department of the Interior, the U. S. depends upon imports for more than half of its supply of six of the basic thirteen raw materials required by any industrialized society - aluminum, chromium, manganese, nickel, tin, and zinc. By 1985 the country will also depend upon imports for more than half of its iron and tungsten, and by the year 2000 imports will have to supply more than half of the copper, potassium, and sulfur that it requires.

Jan 1, 1975

By Robert G. Ditchburn

The NW caldera hydrothermal vent field at Brothers volcano, of the Kermadec-Tonga arc, has associated massive sulfide mineralization. This includes an abundance of black smoker chimneys that contain significant concentrations of copper, lead, zinc and gold (de Ronde et al., 2005; de Ronde et al, 2010, under review). [ ] The oldest volcanic massive sulphide (VMS) samples recovered so far from Brothers have been dated using radiometric methods at GNS Science and found to be c. 1000 years old. By contrast, a volcanic cone that has formed in the southern part of the caldera has no associated VMS. Only elemental sulphur and Fe-oxide crusts are present here, samples of which have been analysed for their trace elements. From d34S values of sulfates and native sulfur, and the volume of gas (dominated by CO2 and H2S) discharging at the cone site, elements being deposited here are considered more directly magmatic in origin (de Ronde et al., 2005; 2010 under review). It has been discovered that deep-seated changes in volcanic activity at Brothers affect the NW caldera and cone site simultaneously, though the mineralogy at each site is so very different. Thus, the cone site is being studied to determine if elements being deposited there can be used as predictors of potential future VMS mineralisation as similar sites have been found at other volcanoes along the Kermadec arc and elsewhere. The frequency of these deep-seated magmatic events is considered important in the formation of Cu-Au-rich mineralization along arcs. The analysis of Fe within resulting hydrothermal plumes (surveyed by surface vessels), and trace elements in rock and mineral samples, are used to help determine the influence of magmatic contributions to the hydrothermal system. To verify that plumes are a reliable proxy for hydrothermal events depositing iron on the seafloor, Fe-oxide crusts from Brothers volcano cone have been dated to see if their emplacement coincides with highly Fe-enriched plumes in the water column. The radiometric dating techniques developed for barite-rich VMS, i.e. using 228Ra and 226Ra, were unsuitable for the Fe-oxide crusts because 210Pb was the only isotope detected by gamma spectrometry. Therefore, new techniques using 210Pb, 10Be and arsenic have been established.

Jan 1, 2010

By Valcana Stoyanova

Data and information for this study were collected in June-July 2009 onboard the RV Yuzhmorgeologiya in the area covers about 7000 km2 in the eastern part of the CCFZ between 10º05? - 10º55?N and 119º25? ? 121º08?W. In accordance with the IOM research program the cruise was intend to acquire both geological and environmental data and information necessary for delineation of nodule deposits and also data for identification of the baseline of benthic ecosystem. Having implementation of its 15-year plan of work for exploration under the contract with ISA, current activities of IOM were focused on nodule fields within prime areas that could be mined in the future. Bottom photographs obtained by towed deep-sea vehicle NEPTUN along 6 profiles with common length about 300 km (Fig. 1). In total, about 11,500 digital photographs (what cover approximately 40,000 m2 of the ocean floor) were analyzed for assessment of nodule coverage and investigation of megafauna (animals, visible in photographs, the dimension more than 2 cm). The giant single-cell organisms Xenophyophorida were the most multiple animals in seabed photographs. Their number on the site area averaged 1187 ind/ha. However, the vertical camera position does not allow counting all xenophyophorids, therefore their valid number is represented 10 times more. According to all available information these protozoans play the relevant role in assemblage of deep-water environment, giving for other animal groups an [ ] additional source of nutrition and a substratum for settlement and attachment. The ophiuroids are found in assemblage with xenophyophorids in many cases, standing on a sediment at their base.

Jan 1, 2010

By Nobuyuki Okamoto

The present three-year long phase of the SOPAC/Japan Deep Sea Co-operative Mineral Resources Programme [Programme], commenced in 2000. The Programme has been funded by the Government of Japan through the Japan International Co-operation Agency (JICA) and the Metal Mining Agency of Japan (MMAJ), since 1985. Field survey activities and associated data analysis and interpretation, for the Programme, has largely been carried out by the Deep Ocean Resources Development Co., Ltd. (DORD). The Government of Japan has, since 1982, recognised DORD as one of its ? Pioneer Investigators? for manganese nodules in the Clarion Clipperton Fracture Zone . Although the objective of this paper is to present the results of the drilling cruise that was conducted from December 2001 to January 2002, within the North Fiji Basin, in Fiji?s EEZ, it will also seek to provide a broad overview of the results of the cruise conducted within the Cook Islands in May to June 2000, as well as present preliminary results of the cruise conducted in the Marshall Islands in June to July 2002.

Jan 1, 2002

By Andrew E. Grosz

The United States is dependent on foreign imports for about 80 percent of its ilmenite, about 60 percent of its rutile, and virtually all of its monazite. Nearshore marine sand deposits and beach-complex sediments in the southeastern United States are important domestic sources of ilmenite, leucoxene, rutile, zircon, monazite, and a number of other less well known economic heavy-mineral (HM) species. Because global onshore reserves of placer titanium minerals may fall short of demand in as few as 20 years, offshore research in HM placers will become more important. The Atlantic Continental Shelf (ACS) defined by the shoreline and the 200-m isobath varies in width for the modern U.S. coastline from a fraction of a kilometer to about 150 km offshore of Cape Cod, Mass., and includes an area of about 3.91 x 105 km2. It probably contains 3-7 x 1011 m3 of sand and gravel which may locally contain commercially exploitable placer HM deposits.

Jan 1, 1986

By M. E. Williamson

A seafloor based robotic drilling system is being developed for the National Institute of Ocean Technology in Chennai, India to support a National initiative for marine methane hydrate research. The system will be capable of core sampling to 150m below the seafloor in 3000m of water under telemetric control of an operator onboard a research vessel at the surface. Unlike previous robotic drilling systems, this unit (designated the ACS) will use wireline methodology to reduce the number of tool handling operations required to complete the borehole (conventional rod drilling requires 2025 tool handling operations to complete a 100m hole, while wireline requires only 48 operations to reach the same depth).