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By P. Mikhailik

Recently, characterized by fast development high- and nano-technology, demand for rare and trace metals has increased. One of such metals is gallium. Gallium compounds, mainly GaAs, are used in medicine, to manufacture optoelectronic devices, microwave techniques, devices of solar power and infrared optics, etc. The basic gallium industrial deposits are known only on land. There are bauxites (50 ppm), nepheline rocks and ores (36-38 ppm, minerals concentrators are nepheline and sodalite), Zn-Pb-Cu ores (5000-12000 ppm, minerals concentrators are gallite, germanite, sphalerite, bornite), sulphide-polymetallic and Pb-Zn ores (10-32 ppm, minerals concentrators sphalerite, chalcopyrite) (Vershkovskya et al., 1998). High concentration of gallium are observed in hydrothermal massive sulphides of a Mid-Okinawa Trough (The South Chinese Sea) and Sujo seamount (The Philippine Sea) (Noguchi et al., 2007). As it is known, deep-sea massive sulphides and associated Fe-Mn crusts are products of hydrothermal fluid discharge. High-temperature massive sulphides precipitation are the first, and low-temperature Fe-Mn crusts deposition is the last process of hydrothermal mineralization (Cronan, 1982). Hydrogenic crusts and nodules of the World ocean are characterized by low concentration of Ga, close to clarke (19 ppm) (Kobaltbogatye.., 2002). Hydrogenic crusts from the Sea of Okhotsk are exception, because Ga concentrations are exceeded clarke in 3,5 times (Mikhailik, et al., 2009). Complex studying of Fe-Mn crusts from deep-sea basins volcanic seamounts of the Sea of Japan has shown their hydrothermal-sedimentary genesis (Mikhailik, 2009). High gallium concentration (up to 850 ppm) was established in these crusts by ICP-MS (Agilent 7500C). Microprobe research (JXA-8100) of samples Fe-Mn crusts has not revealed the gallium minerals concentrators. It suggests that, gallium in Fe-Mn crusts of the Sea of Japan is sorb substance.

Jan 1, 2010

By Timothy F. McConachy, Christopher J. Yeats, Ray Binns

Various kinds of sediment-hosted polymetallic sulfide deposit are known on land in ancient marine sequences, many tending to be larger and more valuable than massive sulfide deposits genetically associated with volcanic host rocks. Often such deposits are attributed to subhalative or shallow sub-seafloor precipitation processes, and structural control by faulting is commonly evident. Apart from the famous but anomalous Red Sea metallic oozes and several NE Pacific sites (Middle Valley, Escanaba Trough, Guaymas Basin), however, modern analogs of the sediment-hosted polymetallic sulfide category are lacking. Some deposits hosted by volcaniclastic rocks, such as JADE (Okinawa Trough) and Suzette (Eastern Manus Basin) are strictly sediment-hosted, but their formation is associated with the igneous activity and they are better considered a variant of the more abundant volcanic-associated polymetallic sulfide deposits.

Aug 24, 2006

By Andrea Koschinsky

Numerous hydrothermal vents occur along the Earth?s oceanic spreading axes documenting the reaction of seawater with hot magmatic rocks. The circulation of seawater through the oceanic crust, the interaction with hot rocks in the crust, and the subsequent discharge of hot metal- and gas-rich fluids into the ocean have significant implications for the cycling of material and energy on Earth. Until recently, hydrothermal activity was unknown from the Mid-Atlantic Ridge (MAR) south of the Equator where the MAR is offset by about 1000 km at the St. Paul?s and Romanche fracture zones. During a British cruise in February/March 2005, the first active hydrothermal vent field was discovered on the southern MAR at 5°S. During our follow-up cruise M64/1 in April 2005, the first samples from this vent field were recovered with the ROV QUEST (Univ. Bremen) and analyzed onboard. The high-temperature vent field is situated in a water depth of 2990 m along a line of collapse pits within a large basaltic sheet flow. A diffuse, low-temperature field occurs in a jumbled sheet flow few hundred meters to the east with warm water streaming out of cavities between lava blocks. Here we show for the first time that boiling fluids of ~400°C are emanating from sulfide-bearing vents at a depth of about 3000 m at a slow-spreading Mid-Atlantic Ridge segment. Although this segment is composed of thick basaltic crust, these fluids are dominated by hydrogen relative to methane. Whereas the active chimneys consist of pyrrhotite, chalcopyrite, and isocubanite, the mineral association hematite-magnetite-pyrite occurs in the inactive chimneys suggesting that the fluids became more reducing in present times. The high hydrogen contents and the high temperature of the fluids as well as the change to more reducing conditions are most likely related to a young volcanic eruption event some 300 m east of the hydrothermal field. The presence of hematite and magnetite may indicate that the upflow zone or even the reaction zone at 5°S used to be more oxidized then at other MOR sites, where the hydrothermal fluids are commonly buffered by the pyrite-pyrrhotite-magnetite (PPM) buffer. Consequently, high iron contents and high hydrogen/methane ratios occur in high temperature fluids from basaltic host rocks rather than being restricted to ultramafic host rocks. Faunal communities at the South Atlantic vents largely resemble those from the North Atlantic vents implying that the large Equatorial fracture zones do not inhibit or obstruct faunal exchange along the Mid-Atlantic Ridge.

Jan 1, 2005

By J. V. R. Prasada Rao

India is dependent for 60% of its annual requirement of copper and the entire quantity of nickel and cobalt on imports from outside the country. Land-based resources are either too meager or of too low a concentration for economic exploitation. This has prompted the country to look to deep seabed re- sources for meeting its rising demand for these metals. The Ocean Policy of the Government of India announced in 1982 talks about the need to map and assess the availability of minerals in the deep sea and to develop necessary technologies for exploration and exploitation of seabed minerals. To be self-reliant such technologies would have to be largely developed, tested and operated indigenously. The adoption of the Law of the Sea Convention in 1982 gave a fillip to India's desire to get into the field of deep seabed mining. India applied for recognition as a Pioneer Investor in Ocean Mining in 1983 and received allotment of a mine site of 150,000 km2 in the Central Indian Ocean in August 1987. Simultaneously, the Government has taken up a programme of development of technologies for exploration of the mine site for resource assessment, environmental monitoring also to meet the commitments like relinquishment of 50% of the area to the Preparatory Commission. Technologies for exploitation of these seabed resource like the mining system, transportation and extractive metallurgy have also been taken up for development in various research institutes largely in the government sector. While India's objective in the long term is to meet the shortage of copper, nickel, cobalt and manganese by the turn of the century, in the short term, the programme aims at application of the seabed mining technologies to meet the immediate needs of the country such as: a. Exploration for oil and natural gas. b. Exploration and exploitation of placer minerals and other deposits at shallow depth in India's EEZ.

Jan 1, 1994

By A. A. Schipaanboord, S. J. Dasselaar

"With the growing global demand for strategic metals, commodity prices are rising and the scarcity of some metals is increasing. Europe’s technology sector is also affected by this growing shortage of metals. Securing the supply of critical metals is now a major element in Europe’s economic strategy. The Blue Mining and Blue Nodules projects have been initiated to principally advance deep sea mining technology beyond current TRL-levels.These critical metals are found inside so-called “polymetallic nodules”, lying on the seafloor in deep-sea environment. These nodules have a typical abundance of 10-25 kg/m2 and a size range of 10-125 mm.Harvesting the polymetallic nodules is challenging. Two main methods of harvesting or collector equipment are distinguished: hydraulic and mechanical. Over the last year, Royal IHC has designed, build and tested a full-scale hydraulic collector. Meanwhile, a mechanical collector is being developed.First, a scaled version of the hydraulic collector was developed and tested in order to have a proof of principle. The development as well as optimization were aided by multiphase CFD simulations."

Jan 1, 2017

By N. Wang

The City of Honolulu mines sand from nearshore deposits for beach maintenance. The suction dredging operation creates a discharge plume which is carried by currents and other motions until it settles out of the water column. The dispersion of such a plume is influenced by distribution of particle size, as well as site dynamics. Interest in dispersion characteristics stem$ from concern about possible deleterious influences of such a plume on the nearshore environment. The behavior of such plumes has been modeled by Brandsma and Divoky (1976), as well as others. This study is an attempt to calibrate a plume model (modified from Brandsma and Divoky's model by Wang), using concentration, turbidity, and fluid velocity measurements of a small plume taken under field conditions. This calibrated model could then be used to predict dispersion characteristics of a much larger plume. Sand suction-dredged at a depth of 12m with a four-inch pipe and discharged at midwater was used to create a test plume closely simulating the conditions found during regular mining operations. Water samples containing suspended material were taken at varying distances from the discharge, from which concentrations were measured in the lab. Transmitted natural light measurements were used to provide estimates of turbidity. Current velocities were measured using current meters, as well as drogue-following methods. These data were then used to help estimate the vertical diffusion coefficient in the model.

Jan 1, 1991

By Stanley R. Riggs

Onslow Bay is a broad, shallow, high-energy shelf system bounded by the Cape Lookout and Frying Pan shoals. It is generally a sediment-starved shelf system dominated by hardbottoms with a scattered and discontinuous veneer of mobile Holocene sediments. Phosphate-rich beds of the Miocene Pungo River Formation crop out in a belt 150 km long and up to 50 km wide across the continental shelf in Onslow Bay, North Carolina. Previous research has demonstrated that a few of these beds contain vast quantities of potentially economic phosphate resources that occur in the surface and shallow subsurface sediments. Onslow Bay contains five phosphate-bearing beds predicted to include up to 20.7 billion tons of in-place phosphate concentrate with total sediment grades ranging up to 22.9% P2O5 and adjusted average concentrate grades of 29.8% P2O5. These phosphates are lithologically and chemically similar to phosphates currently being mined in the nearby Aurora phosphate district in North Carolina. Various lithologies of the Pungo River Formation and associated rock units of Oligocene and Quaternary age crop out on the sea floor to form extensive hardbottom habitats that dominate almost 100% of Onslow Bay. A large proportion of these hardbottoms appear to be sea floor deserts, whereas others are virtual oases with rich associations of benthic organisms. These important differences in benthic community structure appear to be greatly influenced by one or more of the following variables: 1) geologic framework (geologic formation, hardbottom composition, morphology, and spatial orientation relative to dominant currents and waves), 2) texture, movement, and accumulation of surface sediments, and 3) flow rates and chemical composition of discharged submarine groundwater.

Jan 1, 1992

By Sophia Katsouri

Hydrothermal circulation that produces sulfide deposits in the marine environment can also produce sulfide deposits in lakes. The major differences in terms of process are (1) in lakes the hydrothermal fluid is meteoric water of low salinity whereas in the marine setting it is saline and (2) the rocks that are leached of metals to produce the deposits are continental crust in one case and oceanic crust in the other. We have examined sulfides that are presently forming in two lakes ? Lake Tanganyika in east Africa and Lake Oyunuma in Hokkaido, Japan. Tanganyika is the second largest lake in the world and the second deepest rift lake, after Lake Baikal in southeastern Siberia. Two hydrothermal fields are known in its northern basin at Pemba and Cape Banza (Tiercelin et al., 1993). At Pemba, CO2 and CH4-rich, low temperature (53-88°C) hydrothermal fluids are forming decimeter-tall chimneys at 2-46 m water depth. Our microscopic and x-ray diffraction study of samples from the Pemba site reveal marcasite and pyrite to be the most common sulfides. Minor minerals include barite, hematite, bornite and chalcopyrite. Quartz and feldspar are also identified and were probably incorporated from the surrounding lake sediments. At Cape Banza, aragonite chimneys, up to 70 cm high, are venting fluids at 66-103°C.

Jan 1, 2001

By Yannick Beaudoin

The source of base metals in modern seafloor hydrothermal systems can be attributed to leaching of host rocks by hydrothermal fluids and/or potentially by direct degassing of magma. From an economic perspective, metal grade is the most important consideration for seafloor deposits. Tectonic setting appears to be a key factor influencing the development of high grade seafloor base metal sulfide deposits. Back-arcs have a clear advantage over other settings in producing large and rich polymetallic sulfide ores. Microinclusions of magma or so-called melt inclusions trapped in phenocrysts of lavas have contributed to our understanding of the ore-forming process. n this study, we present data from 103 melt inclusions mainly in plagioclase crystals hosted in basaltic to rhyolitic lavas from 9 modern seafloor tectonic settings: oceanic back-arcs (Manus Basin including an ODP Leg 193 drill hole, Bransfield Straits), continental back-arc (Okinawa Trough), mid-ocean ridges (Explorer, MAR), seamounts (Foundation, Axial, Pito), and a transform (Garrett). Most sites host active hydrothermal systems that are producing polymetallic sulfides.

Jan 1, 2005

By Frank Manheim

The purpose of this presentation is to review the history of offshore non- fisheries resource development since World War II, as an introduction to a planned symposium on offshore resources scheduled for the 1996 UMI Conference. After World War II the United States became the leader in offshore oil and gas production, deep ocean drilling technologies, offshore terminals, platforms and production systems, and natural gas recovery and transport. Wartime skills in acoustic profiling and antisubmarine warfare were transferred into commercially important geophysical exploration techniques. The application of ocean drilling and geophysical techniques permitted the recognition and elucidation of plate tectonics patterns, development of seafloor spreading theory, and the transformation of our knowledge of seabed and subseabed strata. After John Mero's studies and recommendations for developing marine manganese nodules in the late 1950's interest in nonfuel minerals grew rapidly. The formation of international deep sea mining consortia in the 1960's was accompanied by a flurry of ocean engineering development, minerals prospecting and associated environmental studies The Santa Barbara Oil Spill of 1969 resulted in a moratorium on both offshore energy and minerals leasing by the Depart- ment Interior, and catalyzed the development of new Federal legislation in 1972. In 1973 the offshore energy moratorium was lifted in response to the Arab oil embargo, and offshore energy activities surged for a time. Minerals were reopened to leasing following President Reagan's 1983 executive order implementing a 200 mile EEZ. Although interest was spurred by

Jan 1, 1995

By Will Roberts, M. E. Williamson

After verification of methodology and testing of prototype systems during 2005/06, Nautilus Minerals expanded their Papua New Guinea (PNG) operations to a full commercial exploration program in 2007. Included was the deployment of sensors and survey systems to locate, characterize and verify massive sulfide deposits with potential as mine sites within the tenements held by Nautilus in PNG. This presentation discusses some of the gear developed and operated during the 2007 PNG investigation.

By Tetsuo Yamazaki

Seafloor massive sulfides (SMS) in the western Pacific have received much attention as resources for gold, silver, copper, zinc, and lead (Lenoble, 2000). Since the end of the 1980s, SMS have been found in the back-arc basin and on oceanic island-arc areas. The typical representatives found are in the Okinawa Trough and on the Izu-Ogasawara Arc near Japan (Halbach et al., 1989; Iizasa et al., 1999), in the Lau Basin and the North Fiji Basin near Fiji (Fouquet et al., 1991; Bendel et al., 1993), and in the East Manus Basin near Papua New Guinea (PNG) (Kia and Lasark, 1999). The higher gold, silver, and copper contents in one of the areas increased the chance for profitable mining operation, which was considered by a private company (Malnic, 2001). The company gathered investment money and announced to start the commercial mining from 2010 (www.nautilusminerals.com). On the basis of geological information of the Sunrise Deposit of the Myojin Knoll on the Izu-Ogasawara Arc (Iizasa et al., 1999) and geotechnical characteristics of SMS (Yamazaki and Park, 2003), some preliminary economic validation analyses of the SMS mining in small production scale were reported by one of the authors (Yamazaki et al., 2003; Yamazaki and Park, 2005; Yamazaki, 2007). The results showed high profitability of the SMS mining.

Jan 1, 2011

By Chan Min Yoo, Jung-Keuk Kang, Wonnyon Kim

Recently high-resolution paleomagnetic age determination of ferromanganese crust in less than millimeter scale has been successfully carried out using a superconducting quantum interference device microscopy magnetometer (SMM). However, it has not been clearly identified how the crust is keeping ancient geomagnetic field records. Here we try to identify magnetic mineralogy of the crust obtained in the Magellan Seamounts, the West Pacific (~20 °N). As a record, age of the crust used in this study is extended to ~10 Ma at ~40 mm depth and ~28 Ma at ~100 mm depth, respectively, based on the combination approach of SMM measurements, Be-isotope and Co-chronology. Thermal demagnetization revealed a Curie temperature of ~560oC, corresponding to (titano)magnetite. Component analysis of isothermal remanent magnetization identified a presence of two types of magnetite. Measurements of first order reverse curve showed a dominance of non-interacting single-domain magnetite, which is one of the intrinsic feature of biogenic magnetite. Although most of the magnetic particles on transmitted electron microscopy are covered by amorphous Fe-Mn minerals, some are observed as a prototype of biogenic magnetite showing a chain of ~10 nm sized magnetite cubes. However, a magnetite signal (i.e., Verway transition at ~ –120 oC) was not detected in low-temperature treatment probably due to surface oxidation of magnetite. Contribution of interacting magnetite of detrital origin is <30% throughout a crust. Interestingly, contribution of detrital magnetite is almost three times higher since ~10 Ma. At this boundary, a growth rate of the crust is double up and flux of other detrital signals, including Al, Mg, Ti and Zr, are also increased.

Jan 1, 2017

By Tae-kyeong Yeu

KIOST has developed the pilot mining robot, named MineRo ?? from early-2011 to mid- 2012. The robot consists of two unit-modules having an identical mechanical structure and hydraulic system. One unit-module has two track systems, two pick-up devices, two crushers, one lifting pump and one thruster. The pick-up device is fitted on the frame of the track device. All actuators are driven hydraulically, which are manipulated by valves and the controllers. Each unit-module is equipped with one dual HPU of 250kW / 4,000V. PWM-16 (INNOVA AS) as hydraulic valve controller is adopted, which outputs PWM signals of 16 channels and can be used under pressure in oil-filled box. To measure angular velocity or displacement of hydraulic actuator, turbine-type flow-meters are adopted. The flow-meter has RF (Radio Frequency) type pulse detector, which extends the flow range by eliminating drag on the rotor. Two track motors, two crusher motors, lifting pump, one thruster can be controlled their velocities through feedback of the measured flow-rates. As well as the flow-rates, the states of the hydraulic system such as hydraulic pressures, temperatures, leakages are measured through a self-developed flow-pressure canister. In that canister, multi-channel amplifier boards are installed, through which the vast amount of data is acquired and transmitted to the main controller using serial communication.

Sep 14, 2011

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&apos;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&apos;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&apos;s mineralogical and chemical investigation. The combined findings of the Bureau and other Task Force agencies have provided information needed to expand the country&apos;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 Sukumar Bandopadhyay

The Marine Minerals Technology Center (MMTC) was authorized by an act of the United States Congress in 1996. The act established several marine minerals research centers in the U.S., including one at the University of Alaska Fairbanks. The Alaska MMTC is funded through the Minerals Management Service of the Department of the Interior and concentrates its research in the Arctic seas region. Recent research projects at the MMTC include, among others, application of a geographic information system (GIS) to the gold placer deposits offshore Nome, Alaska, development of a marine gold placer reserve definition model using a neural network, and development of an expert system model for submarine tailings disposal (STD) planning and decision-making. Although geostatistics remains the most prevalent method used today for ore grade estimation, researchers have made numerous improvements over the years for accurately predicting grades of ore using other estimation techniques. One such technique, the neural network, has recently emerged as an alternative to geostatistics for grade estimation purposes. A neural network is a non-linear, model-free estimator that is well-suited for noisy and/or sparse data environments. Neural networks perform best with non-linear spatial data, contrary to the stationary assumption of ordinary Kriging techniques. In the marine placer ore reserve definition model, the neural network technique was used to estimate placer gold reserves offshore Nome. This study demonstrated the utility of neural network modeling over other traditional ore reserve estimation methods, especially for high cut-off grades. Some of the relevant issues of neural network modeling were also addressed in the study. In testing, the neural network produced results that were close to those from geostatistical techniques including Kriging, polygonal, and inverse distance methods.

Jan 1, 2005

By Mark Lee, Isobel Yeo, Sarah Howarth, Christian Millo, Javier González Sanz, Paul Lusty, Bramley Murton, Pierre Josso

"Seafloor cobalt-rich ferromanganese crusts represent the most important yet least explored resource of ‘E-tech’ elements on the planet (Hein et al. 2003; ISA, 2008; Hein et al. 2010; Hein et al. 2013). These polymetallic deposits form a continuum from nodules rich in manganese and cobalt to crusts rich in tellurium and the heavy rare earth elements (HREE). It is this combination of traditional (base) metals and the extreme enrichment of ‘E-tech’ elements that makes seafloor ferromanganese oxide deposits particularly interesting to both science and society. Recent estimates of the global resource, based on the sparse data available, infers a dry mass of ferromanganese crusts on the seafloor of 35 x 109 tonnes (35GT). Of this, 3.7 GT is predicted in the Indian Ocean, 8 GT in the Atlantic, and 23 GT in the Pacific (Hein et al. 2013).At a global scale, the processes controlling the formation and distribution of ferromanganese (Fe-Mn) crusts are reasonably well understood (e.g. Hein et al. 2000; Verlaan et al. 2004; Cronan 2006; Halbach et al. 1989; Usui and Someya, 1997; Hein et al. 2000; Hein et al. 2003; Hein et al. 2009; Hein et al. 2010; Hein et al. 2013; Muiños et al. 2013; Marino et al., 2016). However, much of this knowledge is drawn from sparse sampling at a regional to ocean basin scale. As a result, there remains a fundamental gap in understanding of the role of local-scale factors, such as micro-topography, ocean currents and upwelling, sedimentation rates, micro-organisms, water mass composition and biological productivity, that are considered potentially crucial to controlling the growth and composition of Fe-Mn crusts. Indeed, quantitative, particularly temporal, information relating to these processes and their relative importance in deposit formation is almost completely absent. Hence, to make any significant advance in understanding these deposits require significant new research."

Jan 1, 2017

By Cheng Xiangzhou

The China Ocean Mineral Resources Research and Development Association (COMRA) conducted a topographic survey in its deep seabed claim area with the SeaBeam system in 19475. After analyzing the data, it was determined that there is a group of living things several hundreds of meters in depth that significantly affect the sound waves in the frequency range of interest. We will attempt to investigate more about such influences. Physical model testing is an important means for studying the theory, and for development of the technology for geophysical prospecting. Because the manganese nodules are distributed over the sea floor in irregular patterns, it is hoped that study of the acoustic properties of manganese nodules by means of physical model testing can improve interpretation of the data of the multi-beam system and the SeaBeam system. This will provide a more reliable basis for delimiting the mineral site and evaluating the reserves in the Pioneer area of China.

Jan 1, 1996

By David Huber, John Halkyard

Deep Reach Technology, Inc. recently completed a multi-year cooperative research project for the U S Army Research Laboratory for the purposes of investigating recovery of rare earth elements from the seabed. This research led to the discovery of a potentially economical deposit in the Exclusive Economic Zone of the Cook Islands. In order to further develop this resource, Ocean Minerals LLC (OML) was formed in 2016 to explore the development of a deep-sea mining project to recover rare earth elements and scandium from the upper 10m of sediment in promising areas of the Cook Islands Exclusive Economic Zone. OML and the Cook Islands Investment Corporation signed an Agreement in 2016 giving OML exclusive rights to explore a 12000 sq km area and option rights over an additional 48,000 sq km. This poster presents the current status and activities related to this project.

Jan 1, 2017

By Sukumar Bandopadhyay

The Marine Mining Technology Center (MMTC) was authorized by an act of the United States Congress in 1996. The act established several marine minerals research centers in the U.S., including one at the University of Alaska Fairbanks. The Alaska MMTC is funded through the Minerals Management Service of the Department of the Interior and concentrates its research in the Artic seas region. Recent research projects at the MMTC include, among others, a geographic information system (GIS) application to the gold placer deposits offshore Nome, Alaska, a marine gold placer reserve definition model using a neural network, and development of an expert system model for submarine tailings disposal (STD) planning and decision-making. Although geostatistics remains the most prevalent method used today for ore grade estimation, researchers have made numerous improvements over the years for accurately predicting grades of ore using various other estimation techniques. As a result, the neural network has recently emerged as an alternative to geostatistics for grade estimation purposes. A neural network is a non-linear, model-free estimator that is well-suited for noisy and/or sparse data environments. Neural networks perform best with non-linear spatial data, contrary to the stationary assumption of ordinary Kriging techniques. In the marine placer ore reserve definition model, the neural network technique was used to estimate placer gold reserves offshore Nome. This study demonstrated the utility of neural network modeling over other traditional ore reserve estimation methods, especially for high cut-off grades. Some of the relevant issues of neural network modeling were also addressed in the study. In testing, the neural network produced results that were close to those from geostatistical techniques including Kriging, polygon, and inverse distance methods.

Jan 1, 2004