Search Documents

In 1983, the GEMINO research project (Geothermal Metallogenesis Indian Ocean) was initiated in order to locate and evaluate sites of recent or fossil hydrothermal activity in the largely unexplored Indian Ocean. During GEMINO cruises 1 and 2 with R/V SONNE in 1983 and 1986, the Central Indian Ridge between 21°S and 24°S was the subject of detailed exploration, including SeaBeam and magnetic mapping, hydrocasts, sediment coring, TV-grab sampling, and camera/video tows. Although hydrothermal sulfide mineralization was not located, a hydrothermal component in the sediment composition, hydrothermally altered basalts, and maximum concentrations of 27.5 nmol/kg Mn and 45.6 nl/l CH4 were discovered (Plüger and Herzig 1986; Herzig and Plüger 1988a). Leg 1 of the GEMINO-3 cruise in 1987/88 identified a neovolcanic ridge in the rift valley of a 30 km segment at 22°55'S as a site of weak hydrothermal activity and photographed smectite-like precipitates on basalt talus and a chimney structure on top of a ridge-parallel fault scarp. Water temperature data and the distribution of Mn and CH4 were interpreted as indicative of diffuse, low-temperature hydrothermal activity (Herzig and Plüger 1988b).

Jan 1, 1989

By Michael Johnston

Nautilus Minerals is exploring for high-grade gold, silver, copper, and zinc-rich submarine massive sulphide deposits (SMS) within the territorial waters of the sovereign state of Papua New Guinea. Work to date has shown that these systems contain spectacularly high metal grades. To date a total of 88 surface sulphide grab samples have been collected from Nautilus’ Solwara 1 Prospect within EL 1196 in the Manus Basin, returning average grades of 15.5 g/t gold, 191g/t silver, 10.8% copper, and 4.7% Zn. Drilling in January/February 2006 confirmed the presence of this high grade system, with sulphide intersections up to 19m below the sea floor, with a best intersection of 11.6m at 9.1 g/t Au and 13.1% Cu.

By Fredrik Søreide

Several potential marine mineral deposits of various types have been identified within the Norwegian EEZ. The Norwegian University of Science and Technology has recently designed and built a new remotely operated vehicle (ROV) system for scientific investigations of the deep-ocean and seafloor. A program to locate and investigate the most interesting of the identified marine mineral deposits using the new ROV system is underway. The ROV has been designed for detailed survey and sampling tasks. Although initially built for a major marine archaeology project, the design is equally suited to locate and investigate marine mineral deposits. The ROV is equipped with a high precision multi-sensory package that consists of various high quality cameras and lighting systems (together with state-of-the-art video and photo mosaic systems), several sonar systems, magnetometer and various other sensors. The ROV is also equipped with a 7-function manipulator arm and an excavation system. Internal collection baskets are used to store material for retrieval to the surface. A closed-loop control dynamic positioning system is used for detailed positioning of the ROV. Position data and other information are stored in a digital data management system. The ROV will also be used together with a specially developed remotely operated tool (ROT). The size and shape of this benthic lander can be adjusted before it is carefully lowered to the seafloor. The ROV can be docked on a moving platform on the ROT, to do detailed scientific investigations. The ROT can also be equipped with a separate sensor and system package, including drilling, excavation and coring units. This paper will present the new remotely operated system and the planned projects in Norway.

Jan 1, 2004

By Gordon B. J. Fader

A regional assessment of the aggregate potential of the Scotian Shelf is presently being funded through a Canada-Nova Scotia Cooperation Agreement on Mineral Development. This assessment includes testing of seabed materials for their suitability in a variety of concrete, asphalt and other specialized applications. The glacial and postglacial Holocene history of the Scotian Shelf has been favourable for the formation of large deposits of sand and gravel that have potential for use as marine aggregate resources. Large banks and inner shelf areas of the seabed consist of basal transgressive sand and gravel of the Sable Island Sand and Gravel Formation. These sediments accumulated during the late Wisconsinan postglacial transgression, through sorting of glacial materials that were originally deposited beneath marine terminating glaciers. Some sandy deposits occur as low-stand deltas on the inner shelf at 70 m water depth and were formed during the maxi- mum low sea level stand, in early postglacial time, at approximately 12 000 yBP. Modern sediment transport processes have contributed to the formation of areas of large sand bedforms, such as the Cape Split sand wave field and other isolated sand waves of the inner Bay of Fundy, and Eastern Shoal on Banquereau. Sandy sediments, found in many transverse channels in the nearshore, offer a potential for placer gold where proximal to adjacent onshore epithermal gold deposits. Lithothamnion covered gravel occurs as a thin lag overlying glacial sediments in much of the nearshore. Relict gravel beach ridges have been eroded and redistributed through sub-littoral processes after passage of the transgressing beach front. Multibeam bathymetry, sidescan sonograms and high-resolution seismic reflection profiles are the main survey tools. Ground truth consists of large volume seabed samples, vibrocores and photographs. A preliminary assessment of the aggregate potential indicates that very large volumes of suitable aggregate lie in the offshore of southeast Canada.

Jan 1, 1995

By Justin C. I. Baulch, Robina Sharpe, Steven J. Downey, John P. Feenan, Kate M. Perrin

Since becoming a public company in October 2005, Neptune Minerals has continued to advance its primary aims. Major achievements in the last year have been: • Successful completion of two simultaneous New Zealand exploration programs, Kermadec 2007 (K-07) and Colville-Monowai 2007 (CM-07); • New discovery of an inactive SMS field on the Rumble II West seamount; • Focused exploration license applications over quality areas of known SMS mineralization in arc and back-arc settings in Japan, Vanuatu, Papua New Guinea (PNG), Northern Marianas Islands (CNMI), Palau, and Italy; • Granting of licenses covering some 200,326 km2 of arc and back-arc within the EEZ of PNG and the Federated States of Micronesia (FSM); • Targeting of an additional mineralization style with extensive applications in PNG covering Conical Seamount-style Au-rich epithermal mineralization; • Welcoming Newmont Mining, one of the World’s largest mining companies, as a major shareholder; • Commissioning a scoping study to investigate options for mining and processing of SMS; Marine Minerals of the Pacific: Science, Economics and the Environment UMI2007 · The University of Tokyo, Japan Baulch 2 37th Underwater Mining Institute · 15-20 October 2007 • Invitation to contribute to, and participate in, the Meteor M73/2 Tyrrhenian Sea research program. The Company has granted exploration licenses covering 263,000 km2 in New Zealand, FSM and PNG, and a further 362,000 km2 under application in Japan, PNG, Vanuatu, Northern Mariana Islands, Palau and Italy.

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

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

Jan 1, 2018

By Anthony Wakefield

Dredging tends to be either horizontal or vertical. In each case solids have to be disengaged from the deposit, mobilized, acquired and elevated or translated. One means of elevation is the airlift. Elevation and translation of essentially granular material nay be by jet pump or centrifugal pump. Any of the three types may be used on its own. The airlift and jet pump may he combined for vertical transport and the centrifugal and jet pumps for predominantly horizontal. Both suction point and pipework must have a means of deployment from the surface or from a submerged vehicle or merely a diver. An airlift is an energetic system, having a source of energy and a means of storing it. It therefore will be difficult to prevent oscillation -surging. A centrifugal pump has a characteristic that bends over at low flow rate and is therefore intrinsically unsuitable for pumping solids. The result is blockage, operation at high velocity and correspondingly high wear rates or operation at low concentration of solids and correspondingly low efficiency. The jet pump is intrinsically exceptionally stable but has a low hydraulic efficiency. The jet pump-airlift hybrid prevents or reduces surging and increases system efficiency away from the optimum depth for airlift operation. Delivered solids concentration is increased. The jet pump-centrifugal pump hybrid totally prevents pipeline blockages and increases the productivity from a given pipeline size. For a given energy input the average production is typically doubled. For example, the Indian River Delaware bypassing pipeline transmits an overall day-in-day-out average of 500t/h (tonnes) of sand down a 10.86" diameter line.

Jan 1, 1998

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

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

Aug 24, 2006

By Kaihui Yang

Volcanogenic massive sulfide deposits are generally considered to have been formed by hydrothermal fluids that leach ore metals out of footwall rocks. However, the necessity for a metal-rich magmatic component in the ore-forming fluid of "giant" ore deposits has been debated over the decades. The solution to this issue is important not only for metallogenic models but also for the mineral exploration. In the hydrothermal leaching model, massive sulfides at mid-ocean ridges are deposited from hydrothermal fluids containing 80 ppm Fe, 6 ppm Zn, 2 ppm Cu, 350oC, and 0.7 g/cm3 density (average data for 21oN East Pacific Rise). A simple calculation demonstrates that such a dilute fluid is unlikely to have been responsible for the formation of the largest ancient massive sulfide ores of greater than 100x106 tonnes, such as Kidd Creek, Brunswick No. 12, Neves Corvo, and Rio Tinto. For such a deposit consisting primarily of pyrite, sphalerite, galena and chalcopyrite (other minerals, including gangue, might account for an additional 10-20%) and even assuming 100% precipitation and retention of the sulfides, more than 790 km3 of vent fluid would be required. For typical water-rock reaction ratios of about 2, this fluid would have to have reacted with about 395 km3 of rock to acquire its metals by conventional leaching processes. This estimate, however, conflicts with the observation that even a giant massive sulfide ore body is usually underlain only by a few cube kilometers of obviously altered rocks. Moreover, this model is not consistent with the observation of hanging wall alteration in many large massive sulfide deposits. The close spatial association between massive sulfides and volcanic rocks, in both ancient and modern sea floors, suggests that direct magmatic contribution should be taken into account in the genetic model. Magmatic fluids, capable of carrying abundant ore metals and volatiles and escaping from magma by depressurization, are well known from modern active volcanoes on land. High concentrations of metals occur in CO2-rich magmatic fluid trapped in felsic volcanic rocks nearby large presently-forming VMS deposits in the eastern Manus Basin (Pacmanus, Suzette) and also in the footwall rocks of Ordovician giant Brunswick #12 deposit in the Bathurst district, New Brunswick. Only 1% of such metal-rich magmatic fluid mixed with heated sea water, that has leached its metals from rocks, would contribute 85% of the total metals to form an orebody. Such magmatic fluids are most likely to be formed from volatile-rich felsic magmas that are prevalent in back arcs, and, if added to the normal circulation system, the fluids could be responsible for the formation of "giant" ore deposits. If this is true, then the study of magmatic fluids in the seafloor volcanic rocks may provide criteria for the exploration of large ore deposits.

Jan 1, 2011

By Michael R. Gipp

Marine Mining Inc. is currently exploring for marine alluvial gold and diamonds on a prospecting licence over a concession that covers 10,000 km2 of the continental shelf of Ghana. The boundaries of the concession extend from 0 30'W to 2 40'W, and between the shoreline and approximately the continental shelf edge north of 4 30'N. This concession extends from Kikam Beach in the west, to Senya Beraku in the east, a distance of approximately 240 km, and seaward an average of about 40 km. The concession is entirely underwater, with the exception of the estuaries of the Ankobra and Pra Rivers. Ghana has been a large source of alluvial gold, with historical production exceeding 25 million ounces. Southwestern Ghana is characterized by Precambrian rocks, which have been folded into a number of NE-SW trending synclines and anticlines. The most significant feature of the Birimian rocks is the presence of evenly spaced gold-bearing greenstone belts. They are 10-15 km wide, separated by about 90 km, separate basins filled by folded metasediments and granitoids. The rivers that enter the concession drain most of the exposed gold-bearing belts of Ghana. Given that approximately 2 km of erosion has taken place since the Mesozoic, and that gold mines on these belts boast proven reserves of over 55 million ounces, it is likely that large amounts of gold have been eroded out and carried to the sea. Coastal fractures, related to Precambrian structures reactivated during Mesozoic rifting, are responsible for the physiography of the coastal area, which consists of high-relief horsts separated by grabens that have been occupied and infilled by rivers or by finer sediments during times of elevated sea level. These fractures were loci of gold mineralization during the Precambrian, and are the source of alluvial gold in rivers confined by them.

Jan 1, 1998

By Dallas L. Peck

The U.S. Geological Survey (USGS) recently completed phase 1 of a mapping effort that makes the United States the first nation to systematically acquire image maps of its underwater lands. In 1984, the USGS, as part of its mission to map and characterize the resources of the Federal lands, began a mapping effort in the newly proclaimed Exclusive Economic Zone (EEZ). The goal was to provide sonar image maps of this frontier area within 10 years. The mapping program is on schedule, with two-thirds of the EEZ sea floor, approximately 2 million square nautical miles, happed in 7 years. The deep water EEZ (depth greater than 200 m) around the 50 states is now complete except for the North Slope of Alaska, where ice precludes our surveying with a surface ship. Phase 2 of the EEZ mapping effort will begin in 1994, focusing on the American Flag islands of the western Pacific. Approximately 1 million square nautical miles of sea floor remain to be mapped around the islands.

Jan 1, 1992

By Christina Pomee, John Parianos

"TOML’s ISA Contract comprises six areas (A-F) that span from 118° to 152° W and from 7° to 15° N or over 70% of the CCZ.During a 2015 exploration cruise, TOML scientists found that the a logging system developed by ISA (2010) was able to be adapted and enhanced, to describe in some detail the varied morphology of nodules both within the TOML areas and between them.The shapes and sizes of nodules seen were then found to relate to substrate type and setting, and thus likely thickness and long-term stability of the geochemically active layer. Consideration of the various processes that might influence growth helps constrain nodule formation further. The nodules effectively record the long-term geochemical conditions that lead to their formation.ISA (International Seabed Authority), 2010. A Geological Model of Polymetallic Nodule Deposits in the Clarion-Clipperton Fracture Zone and Prospector’s Guide for Polymetallic Nodule Deposits in the Clarion-Clipperton Fracture Zone. International Seabed Authority Technical Study: No. 6 ISBN: 978-976-95268-2-2"

Jan 1, 2017

By Ian J. Graham, Cornel E. J. de Ronde

New Zealand lies astride a convergent plate boundary that extends north-eastwards from the Taupo Volcanic Zone (TVZ) to Tonga. This boundary is marked by the Kermadec arc, c. 1200 km of which falls within New Zealand’s EEZ, and which is host to numerous volcanic edifices both on the arc and in a zone immediately behind the arc to the west. In 1999, thirteen volcanic centres in the southern 260 km of the arc were surveyed for their hydrothermal plumes with seven of them discharging vent fluids into the surrounding ocean. Three of the seven volcanic centres have had mineralised rocks recovered from them during dredging and submersible operations, namely Brothers, Rumble II West and Clark. Presentday plume data combined with mineralogical evidence indicate that the vent sites at Rumble II West and Clark are waning, although the presence of Cu-rich sulphides in samples recovered from Rumble II West suggest there may be a massive sulphide (Cu-Zn-Pb-Ba ± Au) deposit located within the caldera. Brothers volcanic centre is host to the largest polymetallic mineral deposit discovered along the Kermadec arc and has numerous, up to 7 m tall chimneys within a c. 600 x 200 m area located on its NW caldera wall. Geochemical data indicate that concentrations of base metals are variable and depend critically on sample type. When combined with mineralogical and plume data, this indicates addition of a magmatic fluid component to the vent fluids.

Aug 24, 2006

By P. A. Rona

The first hydrothermal mineral deposits found at a seafloor spreading center were discovered in the Red Sea by multi-national research vessels between 1963 and 1965. At that time, the deposits were considered a special case related to continental rifting and an early stage of opening of an ocean basin. Since that time, examples of almost all major varieties of volcanic- and sediment-hosted hydrothermal deposits associated with basaltic rocks in the geologic record have been found at present spreading centers. Review of over 100 hydrothermal mineral occurrences presently known at oceanic ridges and rifts indicates that a range of deposit sizes from small to large (> 1 x 106 tonnes) occurs at all seafloor spreading rates. However, larger deposits but fewer per unit length of spreading axis appear to form at slow- than at intermediate- to fast-spreading centers based on available data. Larger deposits are more common in sediment-hosted than in volcanic-hosted settings regardless of spreading rate. A spectrum of hydrothermal deposit varieties (stratiform, stockwork and disseminated sulfides; various forms of sulfate, carbonate, silicate, oxide and hydroxide deposits) occurs in almost all of the tectonic settings. High-intensity, ore-forming, subseafloor, hydrothermal convection systems that conserve heat and mass and concentrate hydrothermal precipitates are extremely localized by anomalous physical and chemical conditions relative to nearly ubiquitous low-intensity hydrothermal activity at and flanking seafloor spreading axes at all spreading rates. Two distinct shapes of volcanic-hosted

Jan 1, 1989

By J. Robert Moore

Introductory remarks will be made by the speaker, chiefly on recent and current developments in the industrial, agency and academic sectors that relate to the status of marine mining and mineral exploration programs and to recommendations for strengthening and continuing these programs. Subsequent to these brief comments, a selected panel with representation from industry, academe and government will address the following related topics: 1) development and objectives of new centers for marine mining technology, 2) cooperative R. and D. programs between academe and the user groups, 3) arrangements for specialized training and student instruction that will provide for educational components, and 4) funding and other support for implementing new centers and new programs. The panel discussion will be open to all UMI participants and whose contributions will be both solicited and encouraged.

Jan 1, 1986

By Robert Corcoran, Piotr Jasiobedzki, Roy Jakola, Michael Jenkin

Vast mineral resources of copper, zinc, cobalt and gold have been identified off the coast of Papua New Guinea at depths exceeding 2,000 meters. Accessing them in a cost effective manner and without destroying the marine habitat requires overcoming numerous technical and operational challenges. Although there are a number of deep-sea mining operations underway worldwide, the depths encountered are significantly less than will be required to mine these ore deposits. To date, only the oil industry has developed technologies for successfully accessing reserves at depths of 3,000m.

By Christian Müller, Hermann-Rudolf Kudrass, Christian Reichert

Recent studies estimate the depletion mid-point (dmp) for conventional natural gas to be reached around year 2022, and for conventional oil to be reached around year 2017. These numbers are based on simplified assumptions of unchanged demand and do not include increasing reserves from discovery of new fields and also do not include a shifting of resources to reserves e.g. due to an increasing oil price (Gerling et al., 2005). Anyhow, these prospects require conventional hydrocarbons to be substituted in the near future.

Aug 24, 2006

By Mayumy Amparo Cabrera-Ramírez

Polymetallic nodules are a widespread resource in the Pacific Ocean, particularly in the areas of Clarion-Clipperton (Cronan, 2000). The most abundant mineral phases are forme d by iron and manganese oxides, with minor elements such as nickel, copper, cobalt, molybdenum and rare earths elements (Cronan, 1977; Cronan and Moorby, 1981; Iyer and Sharma, 1990; Mangini et al. 1990; Banerjee et al. 1991). In the Clarion-Clipperton Zone (CCZ), several authors mention that there are three main mineral species of manganese oxides, which have been recognized and which are associated with different processes of formation: todorokita (Mn2+, Ca, Mg) Mn3 4+ O7. H2), vernadite dMnO and birnessite enriched in Fe and (Na, Ca) 0.5 (Mn4+, Mn3+) 2O4. 1.5 H2O. In nodules of hydrothermal origin have been found todorokite, birnessite, vernadite, goethite and pyrolusite. Although there are many oxides and hydroxides of manganese and iron in amorphous and microcrystalline phases that make up the bulk of the nodule (Frondel et al. 1960; Cronan 1977; Dymond 1981; Calvert and Piper, 1984; Aplin and Cronan, 1985; Martin and Lallier, 1993; Achurra et al. 2009), identifying specific mineral phases is difficult due to the intergrowth of different phases and associated detrital material.

Sep 14, 2011

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 Mayumy Amparo Cabrera-Ramírez

Polymetallic nodules are a widespread resource in the Pacific Ocean, particularly in the areas of Clarion-Clipperton (Cronan, 2000). The most abundant mineral phases are formed by iron and manganese oxides, with minor elements such as nickel, copper, cobalt, molybdenum and rare earths elements (Cronan, 1977; Cronan and Moorby, 1981; Iyer and Sharma, 1990; Mangini et al. 1990; Banerjee et al. 1991). In the Clarion-Clipperton Zone (CCZ), several authors mention that there are three main mineral species of manganese oxides, which have been recognized and which are associated with different processes of formation: todorokita (Mn2+, Ca, Mg) Mn34+ O7. H2), vernadite dMnO and birnessite enriched in Fe and (Na, Ca) 0.5 (Mn4+, Mn3+) 2O4. 1.5 H2O. In nodules of hydrothermal origin have been found todorokite, birnessite, vernadite, goethite and pyrolusite. Although there are many oxides and hydroxides of manganese and iron in amorphous and microcrystalline phases that make up the bulk of the nodule (Frondel et al. 1960; Cronan 1977; Dymond 1981; Calvert and Piper, 1984; Aplin and Cronan, 1985; Martin and Lallier, 1993; Achurra et al. 2009), identifying specific mineral phases is difficult due to the intergrowth of different phases and associated detrital material.

Jan 1, 2011