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By C. Wildman

Prospectivity modeling of seafloor massive sulphide (SMS) deposits has been completed over the Kermadec Arc-Colville Ridge area using the GIS based weights of evidence and fuzzy logic modeling techniques. SMS deposits are the current equivalent of ancient onshore volcanogenic massive sulphide (VMS) ore deposits. These high-grade deposits are formed on the seafloor and commonly consist of a black smoker and metal rich sediment mound complex resulting from the discharge of hydrothermal fluids (up to 400°C) from fractures on the seafloor. Metal sulphides are continuously precipitated in response to mixing of high-temperature hydrothermal fluids with ambient seawater. Accumulation of metal sulphides has led to SMS deposits being potentially major sources of copper, zinc, lead and other metals such as gold, silver, which to date remain untapped. Modeling of SMS deposits was undertaken to illustrate the power of GIS modeling for seafloor resource evaluation and how it can be used to quickly identify and rank in terms of the most likely prospective areas of the seafloor where new SMS deposits might exist. The mineral deposit modeling was constrained by the mineral systems concept which defines those parts of a mineralisation system that are critical to the ore-forming process. The deposits are typically formed in extensional tectonic settings, including both submerged tectonic margins and sea-floor spreading. Volcanic vent systems and underlying dykes, stocks and sills are the sources of heat that are responsible for converting sea water drawn down through fractures in the oceanic crust into an ore-forming hydrothermal fluid. This fluid is then capable of leaching metals and elements from surrounding footwall rocks, which are then transported upwards via the convection of hydrothermal fluids. The ore materials are then precipitated within the black smoker field as massive sulphides due to the mixing of high-temperature (250-400°C), metal-rich hydrothermal fluids with cold (about 2°C) oxygen bearing seawater.

Jan 1, 2011

By Julian Malnic

Transplanting the steps used in exploring and developing mineral deposits on land into the marine environment will help developers. While familiar to oil and gas explorers and many other sea-based industries, the marine environment is so alien to the 90s terrestrial miner that the phrase ?terrestrial mines in the sea? is useful for reinforcing the fundamental parallels in mining sulphides at sea and on land. As on land, the processes of ?pre-feasibility study? and ?feasibility study? will determine the economics of mining a deposit. For many, the step into the sea can detract from the need to follow these familiar and recognised steps used when any new deposit is found on land. The technology to mine sulphides in the 1500 to 2000 m depth range exists. Currently, it is not found in a single, integrated and commercially available system but every element available to build such as system is. Transplanting the thinking of the leaders of the terrestrial mining industry into the sea will perhaps be the greatest challenge and reinforcing the basic steps of discovery - pre-feasibility through to feasibility is the best way to achieve this. After all on land one doesn?t ask ?Can we profitably mine it?? before one can authoritatively answer ?What have we found??. Research by Nautilus Minerals Corporation suggests that the mining of seafloor massive sulphides (SMS) will not only be profitable but potentially lower in both capital and operating costs than prevail in most terrestrial deposits. Nautilus is also acutely aware that with the first SMS deposits under title, it will be setting the standards for seafloor mining into the new millenium. Indeed, we have trained on us not only the eyes of the mining industry waiting to see if SMS deposits really do offer radically better returns, but other stakeholders of the sea and the capital markets. Mistakes by any SMS developer could land all developers in ?hot water?. The rush to exploit our deposits for economic gain will be tempered by ensuring there is adequate public debate and consultation for our environmental code. Failure in any facet of a marine mining development could set back the move to the ocean floor.

Jan 1, 1998

By RB. Pedersen, T. Barryere, E. Reeves, A. Stensland, I. Thorseth, T. Baumberger

Venting on ultraslow spreading ridges is far more abundant then previously predicted, and the discrepancy between observed and predicted vent field density may imply that non-magmatic heat sources are common along these ridges (Baker and German, 2004; Escartin et al., 2008; Rona et al., 2010; German et al., 2016). In this study we have estimated the flux from two hydrothermal vent sites situated on the slow to ultraslow spreading Mohns Ridge at the Arctic Mid-Ocean Ridge system (AMOR). The flux estimates have been made using the primordial isotope 3He in the non-buoyant plume above the Loki’s Castle vent field at the northern termination of the Mohns Ridge, and from the Jan Mayen vent fields area situated close to the southern termination of the ridge. Primordial 3He enters the oceans through degassing and mixing with hydrothermal fluids eventually to be discharged at the ocean floor primarily at hydrothermal vent sites and submarine volcanic eruptions (e.g. Clarke et al., 1969; Lupton and Craig, 1981; Lupton, 1998). Once introduced into the water column the concentration will only decrease by dilution due to its conservative behavior in the water column. Water column samples were collected using a CTD (conductivity, temperature, depth) probe (911plus Seabird) with a Niskin water bottle rosette. The water column above the Jan Mayen vent fields (JMVF) was sampled in the years 2006, 2011, 2012 and 2013 (82 samples) and the water column above the Loki’s Castle vent field was sampled in the years 2007, 2008 and 2009 (116 samples).

Jan 1, 2018

By Frans van Grunsven, Cees van Rhee, Geert Keetels

One of the obstacles during the initial phases of project development is the assessment of the environmental impact. Mining residue, consisting of fine seafloor sediments, are to be discharged subsea to mitigate the impact of these suspended particles. In order to test the effectiveness of discharging in proximity of the seabed, a numerical model is developed within the open source software package OpenFoam. Dedicated laboratory experiments for numerical model validation are discussed within this paper. INTRODUCTION Siltation is considered one of the major pressures on the environment for a seabed mining operation. Siltation is defined as the pollution of water by a high concentration of suspended sediments like clay or silt. This can be caused by two main activities during the mining process: the spill loss during the excavation and the return flow of undesired seafloor sediment after ore filtration on the ship. In a concentrated cloud, these fine particles form a so-called turbidity plume. Prediction of the size of these plumes and the created layer thickness of deposited sediment is a crucial part of the environmental impact assessment. The challenge in predicting the behaviour of these plumes is found in the wide range of scales involved in the process. At the point of origin, the turbidity plumes spread mainly under the influence of turbulent whirls created by an initial momentum and a buoyancy difference due to the presence of the suspended sediment particles. If carried by ambientcurrents, these plumes can spread for several kilometres before blending in the background.

Jan 1, 2018

By James C. Barker

Alaska's expansive continental shelf represents future opportunities for marine mineral development. Although today's metal prices and subsidized foreign mineral production continue to discourage industry investment in marine exploration worldwide, the longer term outlook is one of increasing costs on-shore with a dwindling land-base available on which to search for and extract minerals. Likely, the generations of the 21st century will increasingly recover their minerals from the sea-floor. Though largely unexplored, Alaska potentially represents a major port ion of the U.S. marine resources. Several factors demonstrate this. First, the Alaskan OCS is huge; 74% of the entire United States' continental shelf lies off of Alaska, and 54% of the U.S. coastline is Alaskan. Combined with the jurisdiction waters of the Soviet Far East, the Bering-Chukchi shelf is one of the world's largest tracts of shallow water. Second, Alaska is situated at the northwestern terminus of the mineral-rich American cordillera. From Chile to Alaska, major on-shore deposits of precious and base metals, ferroalloys, and industrial minerals are found in the tectonically disturbed belts of the cordillera. In 1988, the western U.S. cordilleran states produced 70% of this country's mineral output (excluding construction materials). Throughout the cordillera's entire 10,000 mile length, the rock units strike largely parallel to the coastline, but in Alaska they extend directly offshore and onto the continental shelf. Consequently, the mineral-rich terranes off of Alaska have a much more complex interaction with coastal and lit-

Jan 1, 1991

By Paul Kennedy, Daniel R. McConnell, Ruth Price

"The underwater search for the passenger aircraft MH 370 produced rare high resolution datasets of the ocean floor of extraordinary size and detail. The survey design and operations were for sole purpose of finding the aircraft debris field. The aircraft was not found in the detailed search area and the survey was suspended. As planned, the data are now being made available to scientists and researchers. The large survey area includes geologic settings that might be prospective for seafloor minerals. A review of the data can provide insights to seafloor mineral prospectivity in the Southern Indian Ocean and is a large dataset that can be used to calibrate object detection for the design of dedicated mineral exploration surveys.Economic minerals in the Southern Indian OceanOceanographic research and scientific drilling cruises have assembled geologic and geophysical data points in the Southern Indian Ocean. These, together with satellite derived bathymetry and gravimetric data, earthquake mapping, and mapping of magnetic anomalies have, even if they lack detail, produced a general understanding of the main tectonic features and plate movements in the Southern Indian Ocean as well as contributed some marine mineral data.The Southeast Indian Ocean Manganese Pavement, a large manganese nodule field south of Diamantina Fracture Zone was discovered in 1970. Dredging and photographic data from the discovery cruise determined that dense nodule accumulations cover 900,000 sq. km."

Jan 1, 2017

By Wiebe Boomsma

This is a framework study financed by the Maritime Innovation Programme of The Netherlands and several institutions actively involved in the research of the environmental impact of deep sea mining; IHC Mining, MTI Holland, Delft University of Technology, NIOZ, IMARES, Boskalis Westminster, AllSeas and TNO. For this framework study the following mining activities have been identified to be relevant to assess the ecological impact of a deep sea mining operation: a) excavation, b) tailings return, c) vertical transport, d) vessel operations, e) ore transport and f) general operations. For this paper, only one mining activity has been selected as an example for the assessment of ecological effects. This is one of the main activities introduced by the new technology envisaged for developing deep sea mining: tailings return.

Sep 14, 2011

By Matthew Kowalczyk, Steve Bloomer, Peter Kowalczyk

"Mineral deposits found near seafloor hydrothermal venting are of great economic interest. Valuable metals such as gold, copper, zinc, and other polymetallic sulfides are found in appreciable grades in seafloor massive sulfide (SMS) deposits associated with these vents. For mapping these deposits, electromagnetic prospecting is one geophysical method that is very useful because copper/gold rich deposits are highly conductive.Ocean Floor Geophysics (OFG) in 2008 developed the first EM system to successfully map the limits of conductive mineralization in a survey at the Solwara 1 deposit (Kowalczyk, 2008). Since then, towed coincident loop time domain systems have been developed by Waseda University (Nakayama and Saito, 2016) and have successfully detected known mineralization buried at 30m depth. Using a deep tow controlled source electromagnetic (CSEM) array, very clear anomalies have been measured (Murton, 2017) over known mineralization at the TAG field on the mid-Atlantic ridge.In 2014 and 2015, OFG partnered with Fukada Salvage and Marine Co. Ltd. and the Scripps Institution of Oceanography to map methane hydrate deposits off the coast of Japan using a towed controlled source electromagnetic (CSEM) system developed by Scripps. These hydrate deposits are resistive targets, and the Scripps system successfully mapped subsurface electrical resistivity distributions to depths of several 100 metres below the seafloor. OFG is attempting to extend the Scripps CSEM technology to map subsurface conductive SMS deposits to a similar range of depths below the seafloor."

Jan 1, 2017

By Peter M. Herzig

In 1994 and 1998 the German research vessel R/V Sonne undertook detailed mapping and sampling of the largely uncharted offshore areas of the Tabar-Lihir-Tanga-Feni island chain in the New Ireland Basin of Papua New Guinea. The New Ireland Basin occupies a fore-arc position with respect to the formerly active Manus-Kilinailau arc-trench system and hosts a series of Pliocene to Recent alkaline volcanoes which are built on rifted Miocene sedimentary basement. Several of the volcanoes possess high-level porphyry stocks and active geothermal systems, including gold-depositing hot springs and the giant (40 million ounces) Ladolam gold deposit on the island of Lihir. On the southern flank of Lihir island, a group of three volcanic cones were discovered at water depths from 1.000-1.500 m. The volcanoes are located in a narrow zone of recent seismic activity and elevated heat flow (up to 100 mW/m2). The recovered volcanic rocks consist of fresh alkali-olivine basalts, clinopyroxene-rich basalts (ankaramites), porphyritic phlogopite basalts, and trachybasalts. Unusual gold-rich hydrothermal precipitates were recovered from the summit of the 600 m high Conical Seamount located only about 10 km south of Lihir Island. 1200 kg of sampled material systematically collected with a TV-guided grab from the top plateau (150 x 200 m, 1.050 m water depth) are intensely mineralized with pyrite, marcasite, minor sphalerite, chalcopyrite, galena, tennantite/tetrahedrite, and orpiment/realgar together with traces of anglesite, cerrusite, and amorphous silica in stockwork-like veins. Bulk samples of the vein mineralization consist mainly of clays, silica, and disseminated sulfides, and have an unusual high gold content ranging from 1.2-44.0 ppm Au. In some of these samples, grains of native gold (about 1 micron in diameter) were identified by SEM in pyrite and sphalerite. The gold-rich material also contains high concentrations of silver (up to 1000 ppm) and typical epithermal elements such as As (2.6 wt.%), Sb (0.2 wt.%), and Hg (34 ppm). Similar to epithermal deposits on land, which usually have only low base metal contents, the samples from Conical Seamount contain only minor amounts of Zn (max. 4.5 wt.%), Cu (2.0 wt.%), and Pb (2.0 wt.%). Many of the samples recovered from Conical Seamount are virtually identical to the gold ore at Lihir.

Jan 1, 1998

By Carl L. Kaiser

This abstract discusses selected recent technology developments at the Deep Submergence Lab at the Woods Hole Oceanographic Institution aimed at fundamentally changing the nature and scope of AUV operations in the deep ocean. The Autonomous Underwater Vehicle (AUV) Sentry is described in its current configuration with discussion of emerging capabilities. Telepresence enhanced AUV operations are discussed including moving both operations and data processing personnel off the vessel. Autonomous Surface Vessel (ASV) aided AUV operations are discussed including recent experiments where an ASV provided both navigational aiding and a satellite based relay for acoustic communication of telemetery and mission redirection. New flexible communications strategies to perform intervention and manipulation tasks from an untethered vehicle are discussed. The abstract concludes with a brief discussion of industrial collaborations, including the newly launched Center for Marine Robotics.

Sep 14, 2011

By Chan Min Yoo, Kiseong Hyeong, Inah Seo

INTRODUCTION One of the major concerns for deep seabed mining is its environmental impact, from the disturbance of benthic communities due to the mining activity to the disposal of mine tailings back to the ocean. Yet a significant amount of waste materials would be produced from the on-deck processing on the mining platform, all the materials that produced on the mining platform are to be shipped to the land unless the related regulation and guidelines are developed by IMO and ISA (ISA, 2018). Still, ecotoxicology data for the deep seabed minerals from case studies in deep-sea tailings disposal (DSTD) and submarine tailings disposal (STD) sites are lacking and all other related aspects are also largely unknown. This year, the Republic of Korea has started a research project for the more comprehensive understanding of chemical and physical properties of mine tailings from the on-deck processing and the possible environmental impacts on the marine organisms after its disposal. Based on the scientific data collected from this project, Korea would be able to make recommendations for the methods and technical standards for the deep seabed mining discharges. The subjects of this project are threefold: to understand the physical/chemical properties of the tailings, to model the dispersion of particulates after the disposal, and to assess its impact on the marine ecology. Laboratory Experiments Producing Mine Tailings First, the possible waste materials are produced by mimicking the collecting and dressing processes at sea. The polymetallic nodules (PN) would be mined by using a collector lifting the crushed nodules out of the bottom sediment, and the bottom water, accompanying sediment, and the fine nodule particles which are too small to be recovered would be discharged to the ocean and thus are considered as tailings (Schriever and Thiel, 2013). In the laboratory, PN is crushed into the fragments smaller than 2 cm, abraded in the water using the rock mill, and then sieved to obtain the fine particles to be disposed.

Jan 1, 2018

By T. Barryere, R. B. Pedersen, E. Reeves, A. Stensland, I. Thorseth, T. Baumberger

Venting on ultraslow spreading ridges is far more abundant then previously predicted, and the discrepancy between observed and predicted vent field density may imply that non-magmatic heat sources are common along these ridges (Baker and German, 2004; Escartin et al., 2008; Rona et al., 2010; German et al., 2016). In this study we have estimated the flux from two hydrothermal vent sites situated on the slow to ultraslow spreading Mohns Ridge at the Arctic Mid-Ocean Ridge system (AMOR). The flux estimates have been made using the primordial isotope 3He in the non-buoyant plume above the Loki’s Castle vent field at the northern termination of the Mohns Ridge, and from the Jan Mayen vent fields area situated close to the southern termination of the ridge. Primordial 3He enters the oceans through degassing and mixing with hydrothermal fluids eventually to be discharged at the ocean floor primarily at hydrothermal vent sites and submarine volcanic eruptions (e.g. Clarke et al., 1969; Lupton and Craig, 1981; Lupton, 1998). Once introduced into the water column the concentration will only decrease by dilution due to its conservative behavior in the water column. Water column samples were collected using a CTD (conductivity, temperature, depth) probe (911plus Seabird) with a Niskin water bottle rosette. The water column above the Jan Mayen vent fields (JMVF) was sampled in the years 2006, 2011, 2012 and 2013 (82 samples) and the water column above the Loki’s Castle vent field was sampled in the years 2007, 2008 and 2009 (116 samples).

Jan 1, 2018

By S. W. McCandless

Since the mid 1970's, the science of remote sensing has invented and demonstrated sensors that hold unique promise for users that operate in the marine environment. Earlier, visible and infrared sensors provided images and temperature maps of surface conditions, but the 1970's introduced active (radars) and passive (radiometers) microwave sensors capable of penetrating clouds and operating day or night over the world's oceans. Space-based observation satellites permit these systems to span the globe many times each day, providing a view of the world's oceans and Arctic areas consistent with daily and, sometimes, hourly changes in the marine environment. Experimental satellites launched by NASA proved that such systems had great scientific merit, but, even more importantly, they could produce information valuable to marine transportation, fishing, and resource exploration and extraction. This latter subject includes the off-shore search and production of petroleum and natural gas resources and ocean mining as well. A few early satellites, such as GEOS-3, Nimbus-7, and most notably Seasat established that global wind fields, all weather sea surface temperature, ocean topography and sea state, and fine scale images of wave patterns, surfactants,

Jan 1, 1986

By Harald Brekke

On 13 July 2000, the ISA adopted the Regulations on Prospecting and Exploration for Polymetallic Nodules in the Area. The first contracts for such exploration were issued by the ISA the same year. The duration of exploration contracts is 15 years, after which the contractors are expected to go into exploitation. In 2013, ISA with the LTC initiated the process for developing the regulations for exploitation, and are currently working on the first draft to put forward for the Council. In the meantime, the first seven exploration contracts have expired, and been given five years extensions in order for the contractors to get ready to apply for exploitation contracts. According to the current draft of the exploitation regulations, an application for an exploitation contract shall be accompanied by all data acquired during the exploration phase, a mining plan, a financing plan, and a set of environmental plans (i.e. an environmental impact statement, an emergency response and contingency plan, environmental management and monitoring plan, and a closure plan). All of these plans have to be based on substantial scientific and technical data and information. The mining plan requires geoscientific data regarding the mineralogy and grade of the nodules, and the physiography of the mining site as a basis for the consideration of critical aspects, inter alia for making reliable resource estimations, design the mining operations, and forecast revenues. The environmental plans require the input of a substantial set of bioscientific data and information on the exploitation technology in order to establish base-lines, and monitor and evaluate the effects of the mining operations. Under the exploration contracts, such scientific data have been acquired and reported on an annual basis to the ISA. Some testing of mining equipment and experiments on the extraction of metals have also been performed by some contractors. These scientific and technical data from the exploration phase will be the basis for the for the preparation of the studies, plans and documents required for the applications for exploitation. No time frame is specified for the preparations of an application but it must be assumed to take place before the expiration of the exploration contract.

Jan 1, 2018

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 L. B. Khershberg

Marginal seas of the Russian Far East constitute the northwestern segment of the Pacific underwater belt distinguished by distinct metallogenic specialization of shelf-extended ore-bearing magmatic complexes and associated polycyclic mineralization. The coastal part of this vast region is known to contain both multiple placer manifestations and deposits, and non-metalliferous minerals. The latter are sedimentary deposits, the products of weathering, which contain re-deposited placer minerals in industrial concentrations developed on the shelf by certain geological processes. The shelf part of the Far Eastern seas is a seawater-filled continental margin. Complex geophysical mapping and drilling from ships of shelf sedimentary thickness and foundation has revealed the units of contemporary and ancient relief accompanied by formation of industrial concentrations of placer gold, cassiterite, titanium-magnetite, zircon, monzonite, and other components at different stages of placer formation. According to the information collected by prospecting by ?Dalmorgeologia? Co. Ltd. and other companies, placer-host structures within trans-placer-concentrating structures (land-shelf) are: shelf-extended river plains, contemporary and ancient shorelines, beaches, drained areas, spits, bars, detritus deficit zones, and terraces and bodies accumulated underwater in the areas where along-shoreline flows unload their detritus. They all could be used as criteria/signs for mapping and targets for placer prospecting.

Jan 1, 2004

By Charles L. Morgan

"In 2012 the International Seabed Authority (ISA) established nine “Areas of Particular Environmental Interest” (APEIs) for consideration as future Marine Protected Areas to help preserve the biodiversity of life on the seabed within the Clarion-Clipperton Zone (CCZ) between Baja California, Mexico, and the Hawaiian Islands. The CCZ is believed to have a high potential for future seabed mining operations. Areas under active exploration contracts in the CCZ, plus the areas currently reserved by the ISA for exploration by developing nations, comprise about 1.9 million km2 of seabed area. The currently designated APEIs consist of more than 1.4 million km2 of seabed. Each APEI includes a central primary conservation area of 200 X 200 km, surrounded by 100-km buffer areas on all sides. The 100-km buffers are intended as a very conservative spacing between the primary conservation area and potential mining activities in adjacent seabed. The selection of these nine 400 X 400 km APEIs, has been criticized as possibly not including sufficient representative habitat similar enough to the potential mining areas (identified currently as the exploration contract and reserved areas administered by the ISA within the region) to ensure protection of the biodiversity that might be impacted by mining.An area to the east of the existing exploration contracts and reserved areas is known to have substantial mineral deposits; it is very similar to the adjacent exploration contract areas in its geology, environmental setting, polymetallic nodule abundance and nodule metal content. Because it is located in the northeastern extreme of the CCZ, this area is also likely to have relatively high densities of benthic life, compared with benthic communities further westward within the CCZ. Many options for the designation of this APEI are possible, but the area designation must accommodate the boundaries of the Exclusive Economic Zones of Mexico and France.This paper discusses why the selected region in the eastern extreme of the CCZ is a good candidate for designation as a new APEI.Keywords: polymetallic nodules, Marine Protected Areas, Clarion-Clipperton Zone, Areas of Particular Environmental Interest"

Jan 1, 2017

By Stephan K. Schwank

In mid 1993, Bauer Spezialtiefbau GmbH, based in Germany got the order to develop a sampling tool capable of penetrating all different types of seabed sediments including cobbles and boulders and into bedrock. BHP and their partners Benguela Concessions Ltd., had been convinced by the Bauer Trench Cutter Technology and a large scale test in Germany that this system will be the right one to fulfill their expectations for sampling the diamond area off the coast of Namibia. The technique of the tool is based on Bauer's standard cutter technology, which is widely used for the installation of cut-off and diaphragm walls all around the world. The two counterrotating cutter wheels with 12.1 tom torque each cut an area of 3 x 1.2 m (up to 3 x 3 m are possible). The material mixed with seawater was then pumped to the separation plant on board the vessel Geomaster with a capacity of approximately 700 m3/h. Cutter wheels and mud pump were mounted on a special cutter frame and connected by wire ropes and hydraulic hoses to the vessel. An outer frame with four telescopic legs supported the cutter vertically on the uneven seabed and allowed a controlled penetration of the tool up to 6 m into the diamond bearing ground. The tool required a total power installed of approximately 800 kW. All hoses, the 6-inch mud hoses as well as the hydraulic hoses, were stored and compensated on drums on board suitable for a water depth of up to 200 m. Launch and recovery of the tool was effected through the moon pool of the vessel and the 25 m high, special designed drill tower. The 65? to sampling tool had been commissioned in early 1994 in Cape Town. After intensive testing the sampling programme of more than 4000 holes could be successfully completed by January 1995.

Jan 1, 1998

By Jan Willem van Bloois

IHC Merwede is world market leader in the construction of specialist dredging equipment; it is a company with a rich history. The Netherlands is a coastal western country for which water management is a very important issue. Without the enclosure of the coastal areas with dikes and dunes almost two third of the Netherlands would be flooded. These activities are mostly performed by the dredging industry and are the foundation of the dredging industry as it is today. Besides land protection this industry also carries out infrastructure maintenance and performs land reclamation projects. In essence the dredging industry is specialized in horizontal excavation activities and operations in shallow waters with the purpose of gathering bottom sediments and disposing it at a different location. The development is that the activities are moving to deeper waters to a depth of up to 150m. A few years ago IHC Merwede received a request to perform the shallow water excavation techniques at a depth of approximately 2000 meters for the deep sea mining market. In response to the increasing number of requests for deep sea dredging and mining application solutions, IHC Merwede combined all of its activities in this sector to create a new, specially equipped operational unit, IHC Deep Sea Dredging & Mining (IHC DSDM).

Jan 1, 2010

By V. M. Hamza

Analysis of ground and airborne radiometric measurements in the Saquarema region (Rio de Janeiro) provides new insights into the breakdown and transport of mineral aggregates containing monazites, under sub-tropical weathering conditions. The breakdown process, accompanied by loss of low-density clay fractions in weathered materials is considered responsible for the observed patterns in relative enrichment of thorium and uranium along the migration paths of radionuclides. The characteristic features of these patterns provide clues as to the time and distance scales associated with processes of weathering and erosion. It is also possible to determine approximate locations of concentrations of accessory minerals. In this context, we advance the hypothesis that large under-water monazite deposits may be present along the offshore sand banks, in the coastal region of the state of Rio de Janeiro.

Sep 14, 2011