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By Arturo Carranza Edwards

One hundred ninety nine beach face sand samples from an equal number of beaches from the Mexican Pacific were studied. Based on petrological and chemical analysis some locations have been studied in more detail. Black sands from the following areas are discussed: (1) west Baja California Peninsula, where black sands rich in magnetite and ilmenite have maximum values of 50% iron and 14% titanium in the very fine sand fraction; (2) east Gulf of California, in its northern portion, the black sands show maximum values of 43% iron and 5% titanium in the fraction 2 to 4 0;-(3) the south Mexican Pacific, characterized mainly by medium sands, moderately well sorted, show that the fine sand fractions reach values of 35% iron and 41% titanium. X-ray fluorescence applied on selected samples constituted by feldsarenites and lithic feldsarenties, showed the presence of rare elements in some of the studied samples.

Jan 1, 1994

By W. H. Pelton

Polymetallic sulphide (PMS) deposits have recently been discovered associated with hydrothermal vents on the sea floor off Vancouver Island, B.C. Visual estimates indicate reserves in excess of 1 million tons. Reliable reserve estimates have not yet been made, however, due to the extreme difficulty of drilling cores in 2 km of water. Few geophysical techniques can aid in the exploration of these deposits. There is little or no difference in radioactivity, magnetic susceptibility or electrical resistivity between the deposits and the surrounding sea floor sediments. This precludes radiometric, magnetic, electromagnetic and resistivity methods. There is a density contrast, but the logistics of gravity surveys at such depths are formidable. The physical property which shows the most contrast with the sea floor sediments, and which is perhaps one of the easiest to measure (with modern equipment) is polarizability. The induced polarization (IP) method is one of the major electrical geophysical techniques for exploring for PMS deposits on land.

Jan 1, 1985

By S. W. Chang, James R. Hein, S-R. Lee, A. Zondervan, H. Choi

"Nine Fe-Mn nodules from the extensive nodule field in the east of Campbell Plateau of southwest Pacific Ocean beneath the Deep Western Boundary Current (DWBC) and Antarctic Circumpolar Current (ACC) were analyzed for the 10Be/9Be dating by AMS (Accelerator Mass Spectroscopy) at IGNS, New Zealand.Several types of nodule morphology were identified including distinctive discoidal forms with overgrowths resulting possibly from overcrowding and partial sediment burial. Five principal nodule facies were also recognized by location and occurrence (Fig. 1) (Wright et al., 2005). Fe-Mn nodules show various concentric internal growth textures, such as, cuspates, large parabolic cuspates, pseudo-columnar, columnar, globular, and laminated, which vary even in a nodule with hydrogenetic, early diagenetic, or mixed origin. Each texture shows micro-textural varieties and different mineralogy and/or chemistry. The genesis of each internal texture was indicated by the REE patterns, the mineralogy of Mnoxides, and the Mn/Fe ratios."

Jan 1, 2017

By Jonguk Kim

Hydrothermal exploration aboard the R/V Onnuri was performed along the northern Central Indian Ridge (CIR) between 8°S and 12°S in January 2010. The main objectives of this first Korean research cruise on mid ocean ridge system was 1) to understand the nature of spreading segments of the northern CIR area, where no systematic survey have been operated before, by mapping and sampling of volcanic rocks and 2) to discover new hydrothermal venting along the spreading center of northern CIR. During the first leg (IR09 Leg1) bathymetric data, in ~50 km width, were collected by multibeam echo sounding system (EM120), which reveals the exact location and structure of axial rift valley of northern CIR between ~ 8°S and 17°S. Then, rock sampling and CTD casts and tows were performed in northern half of the multibeam survey area in the second leg (IR09 Leg2). The results of bathymetric survey clearly display ocean core complex between 10°S and 11°S. The ocean core complex is featured by topographic-high area with corrugated surface. Lineament of corrugations of the ocean core complex are clearly perpendicular to abyssal hill direction which are triggered by symmetric-normal faults. Symmetrical and asymmetrical segments are characterized by parallel abyssal hills and ocean core complex and/or subparallel abyssal hills, respectively. Geochemical analyses of basaltic glasses from spreading axis show geographic trend of increasing of incompatible elements north to south along the spreading axis, which might be influenced by Reunion hotspot plume. However, local but clear enrichment of incompatible elements is observed in volcanic lava from segment 2, which suggests possible local mantle heterogeneity of uncertain source. Lots of serpentinite and gabbroic rocks with coarse-grained feldspar was recovered in the ocean core complex. Ultramafic and/or mafic rocks indicate the gentle-domed block was traveled from upper mantle. Along the spreading axis of the northern CIR, significant hydrothermal plume signatures were detected by CTD castings and tows. Plume signatures were observed at all 5 surveyed segments, suggesting vigorous hydrothermal activities along the northern CIR. However, the optical signals (light transparency and backscattering) of the nearly every cast along the axial valley of the CIR showed increased background level, which might be due to higher level of suspended particles within the axial valley not only by widespread hydrothermal plumes but also by other processes like resuspension. Onboard dissolved methane analysis indicates that the greater part of the plume signals are originated from hydrothermal venting, not by resuspension. However, more detailed examination, including analyzing additional hydrothermal tracers, need to distinguish actual hydrothermal plume signature.

Jan 1, 2010

By Daisuke Monoe, Kisaburo Nakata, Rika Takeuchi, Tetsuo Yamazaki, Tomoaki Oomi, Tomohiko Fukushima

There are generally two methane passes in conjunction with the seafloor natural cold seepages, as is schematically shown in Fig. 1. The first pass consists of the coupled anaerobic oxidation of methane and anaerobic sulfate reduction, as well as sulfur oxidation in the bacterial mats and immobilization thereafter in the sediment layer and on the seafloor. Through the first pass, calcium and organic carbonates are formed in biological and chemical processes from the methane (Luff and Wallmann, 2003; Luff et al., 2004). The detailed structure of the seafloor methane consumption process unit and its biological and chemical processes were introduced in Yamazaki et al. (2005). The other pass consists of direct bubbling into the water column. Through this pass, organic carbonate is formed with biological oxidation, and a small amount of the methane escapes into the atmosphere. Methane flux is supplied to these two passes through the sediment layer from the deeper structures. The structure of the methane supply process unit was introduced in Yamazaki et al. (2006).

Sep 24, 2006

By Raymond A. Binns

In this first sub-seafloor examination of an active hydrothermal system hosted by felsic volcanic rocks at a convergent plate margin, we drilled 13 holes altogether, achieving deep cored penetrations at two sites. Our aims were (1) to delineate the lateral and vertical variability in mineralisation and alteration patterns below the PACMANUS hydrothermal site near the 1650-1700 m-deep crest of Pual Ridge in the eastern Manus back-arc basin, so as to understand links between volcanological, structural and hydrothermal phenomena, and (2) to establish the nature and extent of microbial activity within the system. Technological innovations vital to success included our precise location of holes on small targets with drill-stem video, the use of a new hard-rock re-entry strategy, and deployment of casing with a new hammer drill. Other technical achievements were the first ODP application of an advanced diamond coring system, and the first direct comparison in a hardrock environment between structural images obtained by wireline methods and by logging-while-drilling (resistivity-at-bit).

Jan 1, 2002

By Walter L. O?Niell

The Continental Shelf Division of the Marine Minerals Technology Center has recently completed field tests of the percussion- waterlift drill and the vibracore/vibralift convertible drill. The two systems have been modified from existing drills to increase their effectiveness and flexibility for nearshore minerals exploration. Originally the percussion-waterlift drill was designed for iand based operations, but it has been modified for use in protected shallow water areas. This drill is easily maintained, inexpensive to construct and operate, and is able to accurately recover representative samples from a variety of sedimentary deposits. Sampling is accomplished using either a reverse circulation method for the recovery of a slurry of sediment cuttings and water or employing a thin walled "Shelby tube" to core zones of interest. The vibracore/vibralift convertible drill is a modification of the remote placer drill (RPD). By combining these drills into one convertible system, it is possible to recover continuous cores of unconsolidated fine-grained sediments (vibracore), a slurry of clay to gravel size sediments over 1.0 meter intervals (vibralift), and to sample sedimentary material in environments where indurated

Jan 1, 1991

By Alexander Malahoff

A shipboard research system capable of operating in waters of up to 2,000 m has been designed and implemented by the Hawaii Undersea Research Laboratory (HURL), University of Hawaii. It uses a remotely-operated ocean bottom survey camera system, ROV, bottom TV grab, the PISCES V submersible, and a submersible emergency recovery system aboard the 225-foot RN KA'IMIKAI-O- KANALOA. All systems are operated from the stern of the KA'IMIKAI with a mounted Caley telearm and articulated A-frame system. The system was designed for multi-purpose use of the telearm for launch and recovery of the PISCES V submersible on a lift recovery line (with or without diver assistance), or night-time operations with an electro-optical cable using either the HURL ocean floor sidescan, or photo and video system operated at 10 m above the ocean floor. The 1.14-inch diameter cable is also used to operate the RCV-150 garage/ROV system. The garage/ROV system has also been designed to act as a submersible rescue system with a submersible lift capability.

Jan 1, 1992

By V. Alexandrov

This paper presents the results of theoretical investigations of the energy requirements of the hydraulic lifting of mined materials from the seabed to the sea surface in the deep-sea mining of solid minerals such as manganese nodules in the Clarion-Clipperton region of the Pacific, situated on the sea floor in water depths of 4,500 m or more. The principal element of the developed underwater transport system is the Underwater Chamber, which is connected by flexible pipeline to a mining machine that gathers nodules from the seabed, mixes them with seawater, and feeds them into a flexible pipeline. In this paper, we discuss the question of the optimum water depth for placement of the Chamber, the interior of which is designed to maintain a 1-atmosphere pressure. We present a method for calculating this depth as it relates to the mechanical characteristics of solid particles, the shapes and size distributions of the particles, particle and slurry density, and other properties. These investigations were carried out in hydro-transport laboratory of the Saint-Petersburg Mining Institute and the hydraulic laboratory of Faculty Environmental Engineering in Wroclaw Agricultural University. KEY WORDS: deposit, nodule, flexible pipeline, pressure drop, concentration, hydromixture

Jan 1, 2005

By Amy Gartman

"Seafloor hydrothermal systems result in the emission of abundant particles and nanoparticles into seawater1. Many of the elements in these particles settle locally, although some are transported distally to the global ocean2. Although broad similarities exist, the mineralogy, size and therefore reactivity of particles emitted varies between sites in the global ocean, and even within sites at the same vent field. The particle geochemistry of these vent fields is a critical but little understood component both from a perspective of baseline characterization and potential environmental impacts.The mining of seafloor massive sulfides formed from hydrothermal venting will generate a new class of particulates in the deep ocean. Broadly, black smoke and SMS tailings exhibit similarities including abundant Cu, Fe and Zn sulfides, and a large number of submicron particles. In addition to the major minerals, minor minerals including As, Bi, and Pb are present, especially in back arc settings. However despite broad similarities, natural “black smoke” and crushed sulfides created during mining operations differ significantly in size class, morphology, abundance, and reactivity. A comparison of these two classes of particulates will be presented, including chemical composition and reactivity to dissolution and oxidation."

Jan 1, 2017

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 B. S. Ingole, S. Jai Sankar, A. B. Valsangkar, R. Sharma, B. Nagender Nath, N. H. Khadge, P. A. Loka Bharathi

After the simulated ‘mining’ experiment (INDEX) in the Central Indian Ocean (in 1997); the restoration of benthic environment was monitored for 4 years (2001-2005) at 5 locations in and around the test site and at 3 reference stations (20-80 km) from the test site. A comparison of long-term monitoring data with the pre-mining and post mining observations has shown that: • The concentration of silt fraction which was the highest (50-60%) at most locations during ‘pre-mining’ and ‘post-mining’ phases, had reduced (40-50%) during monitoring phases. • There was a corresponding increase in clay concentration (50-60%) during the monitoring phase, implying change in the size of sediment particles settling on the seabed, a trend that was also observed at the reference locations. • The initial increase in water content and decrease in shear strength after the experiment, which appeared to be returning to normal in monitoring-1 (2001), was reversed during subsequent monitoring phases (2002-2005), indicating changes in benthic environmental conditions. • Sediment organic matter and pore-water chemical data have not only indicated partial restoration of geochemical properties after the experiment, but also cyclic changes during the monitoring period.

Oct 15, 2007

By Ning Yang, Sup Hong

INTRODUCTION Metal components contained in deep-seabed mineral resources are being highlighted as “energy metals”, which are widely utilized in the entire fields of energy: harvesting and generation, storage and transportation, and saving. Those are mostly trace and rare metals, and rare earth elements as well: manganese, nickel, cobalt, copper, molybdenum, tellurium, selenium, platinum, etc. Toward low carbon society, for global sustainability, the role of metals and minerals is growing up in industries of energy and transportation [1]. In this context, the production and supply of energy metals from deep seafloor have to be approached also based on sustainable development. In deep-seabed mining activity, the sustainability is focused on potential impacts on ecosystems in benthic area and water column. The environmental impacts in deep-seabed mining are caused basically by intervention in benthic zones and transportation of materials. Those are, in particular, removal of benthic habitats, generation and dispersion of sediment plumes, surface transportation of seawater and sediment, tailing from mining vessel, sound and light noises, and chemical leakage, etc. This paper is aiming at fundamental guidance towards sustainable mining of polymetallic nodules.

Jan 1, 2018

By Robert M. Owen

The reconstruction of ocean history has been a major focus of marine research over the past decade. A significant outcome of these investigations is the recognition that certain types of marine mineral deposits are linked to regional to global scale changes in ocean composition and climate conditions. Manganese-bearing deposits are of particular interest in this regard because changes in their occurrence, distribution and/or composition are responsive to both biochemical and geological factors. Analyses of such deposits whose formation spans critical age/epoch boundaries thus provide clues concerning the interplay of different process during anomalous periods in Earth history. Recent studies demonstrating this deposit - event - process relationship include: (1) Changes in the bulk chemical composition of ferromanganese crusts during the Late Miocene-Early-Pliocene (-7-3 Ma) that coincide with a period of enhanced biological productivity in the eastern equatorial Pacific upwelling zone; (2) The formation of large statiform manganese deposits at the Cenornanian- Turonian Boundary (-92 Ma) in association with widespread oceanic anoxia; and (3) Increased deposition of hydrothermal precipitates caused by tectonic reorganizations at the Paleocene - Eocene boundary (-55 Ma) that resulted in global-scale changes in atmospheric and oceanic circulation and climate.

Jan 1, 1995

By N. J. Poll

The Zacarias gold-silver-barite deposit appears to be a Precambrian analogue of present-day exhalative deposits on the sea floor. Geochemical, stratigraphic and structural studies of the latter can be useful in elucidating the ore environment at Zacarias, thereby assisting exploration. The Zacarias mine is about 300 km north of Brasilia, within the Goiás Massif, Brazil. It is the southernmost of three auriferous quartzite occurrences along 1 km of a northeasterly striking amphibolite. Zacarias and its neighboring smaller deposit to the north, the Central Pit, contained a premining ore reserve of 650,000 tons at 4.4 g/t gold, 48 g/t silver, and about 20% barite. Gold mineralization is hosted by concordant quartzite strata also containing layered barite, pyrite, barium-mica, sphalerite, galena, chalcopyrite, magnetite, sulfosalts, free gold, and electrum. The host amphibolite is intercalated with barren mica-quartz-chlorite-pyrite schists that are more voluminous in the footwall and are associated with the ore horizons. Above the amphibolite in the hangingwall lies a thin graphitic shale, then a feldspathic arenite. The strata and regional foliation strike northeast and dip 42° northwest. Crenulation and small-scale folds plunge 30 to 40° to the west.

Jan 1, 1993

By Mikhail D. Ageev

The paper concerns with some questions of Autonomous Underwater Vehicle (AUV) control system design, which allows a motion at rough undersea terrain. The AUV advantages reveal itself completely during exploration of such objects as seamounts and reefs area. These objects are characterized by steep slopes (30 degrees and above) and chaotic situated obstacles (rock debris, pinnacles, escarpments). Uses of other technical facilities for operating in such formations are difficult, dangerous or impossible. These regions take an interest due to the presence of iron-manganese crusts. Modern AUV can estimate density of mineral by means of still camera or video recorder. For this reason the vehicle has to move with the distance of 3-5 meters from seabed. Under such conditions micro- and mesorelief presents a considerable danger for AUV. The AUV can bypass underwater obstacles in the various ways. However, in any case AUV motion will be characterized by intensive maneuvering on various speeds (from 0 up to 1.5 m/s), circular change of tractive force vector and, hence, a circular flow about the hull. So, AUV is equipped with the propulsion system, which provides free modes of motion.

Jan 1, 2003

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

By Ulrich Schwarz-Schampera

Submarine hydrothermal vents and associated mineralization on the Tonga arc have been identified in the summit calderas of two shallow-water volcanoes. The highest temperature vents (up to 270°C) occur at water depths between 430 and 540 meters below sea level (mbsl) near the summit of one volcano at 24°S (volcano 19). Clusters of large barite, anhydrite, and sulfide chimneys on the summit cone are vigorously discharging clear hydrothermal fluids with temperatures on the seawater boiling curve. There is abundant evidence of phase separation and associated gold and base metal precipitates. Pyrite, marcasite, wurtzite-sphalerite, tennantite, and chalcopyrite line the interiors of the highest temperature vents. Acid-sulfate alteration of basalts and basaltic andesites is evidenced by intense silicification and the presence of abundant alunite. One volcano at 21°S (volcano 1) has a chain of explosion craters on the flank of a neovolcanic scoria cone and associated massive pyrite, barite and native sulfur deposits at a water depth of 210 mbsl. Intergrowths of pyrite and enargite are associated with intensely argillic altered basaltic andesites. The reported alteration and Au-enriched mineralization styles of these vent fields are similar to other shallow water hydrothermal systems at island arc volcanoes and contribute to the diversity of seafloor hydrothermal activity in the western Pacific region.

Jan 1, 2010

By M. C. I. Modenesi, J. E. Smith, M. Salvá-Ramírez, G. M. Castro, J. C. Santamarina

Annual metal consumption per capita has increased several orders of magnitude worldwide since the turn of the 19th century, yet grades of terrestrial ores are decreasing as reserves dwindle. Consequently, deep sea metal deposits are gradually transitioning from identified resources to economically viable reserves. Deposits in the Red Sea deeps along the axial trough result from tectonic and local hydrothermal processes. Continental rifting and ocean floor spreading produce fresh oceanic crust; concurrently, seafloor evaporites flow into the spreading zone and form isolated deeps. The deeps are often filled with hot stratified brines maintained by locally discharged fluids during hydrothermal circulation. Metalliferous sediments precipitate from the brines within the deeps. The ongoing multipronged study at KAUST involves: (1) acoustic characterization of the metalliferous accumulations using advanced signal processing techniques that capture the physics of granular materials; (2) comprehensive mineralogical and textural characterization of sampled sediments using SEM, EDS, XRD, XRF, and ICP-OES; (3) multiphysics instruments deployed to measure undisturbed sediment properties in-situ; (4) development of a distributed seafloor observatory for monitoring field operations; (5) innovative concentration and separation technologies; and (6) new strategies for proper tailings disposal purposely conceived for the unique field conditions in the Red Sea deeps.

Jan 1, 2018

By Ian Selby

Recent offshore diamond exploration has been concentrated in the SW Joseph Bonaparte Gulf. I`IW Australia. Extensive high resolution seismic and sampling surveys have been carried out in Cambridge Gulf, offshore of the mouth of the OR River and other rivers of the region. Surface-tow boomer surveys have been correlated with sampling data from vibracores and a wide diameter (1m) airlift system, providing a geological framework for the area. Although large-scale bulk sampling has not been undertaken, there has been no reported recovery of diamonds since 1993. The geology and prospectivity of a range of potential diamond traps in high energy, fluvial and transgressive depositional settings has been assessed. Potentially diamondiferous targets include (i) a shoreline apron. (ii) fluvial/estuarine channel infills and terraces and (iii) ravinement surfaces.. Although there is evidence for a long history of fluvial development and sea level changes, the majority of the investigated traps represent the result of erosion and sedimentation during and following the last interglacial. Significant volumes of unconsolidated gravels and coarse-grained sands with occasional indurated layers are present, and are locally exposed at sea beet In place s thick successions (>5m) of fine-grained overburden overlie the coarse-grained sediments.

Jan 1, 1998