Ferromanganese Nodules Research Articles

Dynamics of formation of ferromanganese nodules in the Indian Ocean

The ferromanganese nodule resources of the Indian Ocean Nodule Field (IONF) are second only in the world in terms of metal content and abundance. Since it was made known by Mero (1965) that several trillion tonnes of manganese nodules lay in the world oceans, extensive exploration for nodules has been undertaken during the last four decades. The possibility of harvesting an inexhaustible supply of nodules from oceans has resulted in formulation of several national and international programs. India started her search for ferromanganese nodules in 1982. The investigations have resulted in a comprehensive assessment of manganese nodule resources at the ocean-level, and on inter-basin model for nodule growth, albeit with several inaccuracies. We list some of the essential requirements for the formation of nodules including the availability of nucleating materials, presence of metals in water column and sediment, favourable tectonic and physiographic features, helpful acoustically transparent sediment–water interface, low rate of sedimentation, presence of nutrient-rich bottom water mass and an oxidizing environment. We present here an integrated assessment of process of formation of ferromanganese nodules from the IONF, which are variable even on scale of metres. This assessment will help evaluate the metal potential of these nodules more realistically, and the model should bring about a predictive estimate of other nodule-bearing areas in the world oceans.

Rare earth elements in the ferromanganese formations of Lake Baikal

VIMS under the supervision of S.V. Kordyukov. The measurement accuracy (±5%) was controlled using the international standard of ferromanganese nodules from the Pacific Ocean. Silica and phosphorus were

Geochemistry of ferromanganese nodules in the Gulf of Finland, Baltic Sea

Distribution of the major and trace elements in ferromanganese nodules, which are buried or exposed on the seafloor, and in host sediments was studied in ten concretion/sediment pairs by various physical and chemical methods. It has been established that, in addition to Fe and Mn, a limited number of the major and trace elements (P, Ca, Sr, Ba, Mo, Co, Zn, Ni, As, Pb, Sb, Tl, U, W, Y, and Ga included) is accumulated with a variable degree of intensity (relative to sediments) in the concretions. As compared to host sediments, the maximal content of Mn in concretions is 100 times higher, whereas maximal contents of all other elements listed above vary from more than one to 10–20 times. Manganese and, to a lesser extent, Ba and Sr are concentrated in the buried concretions. Other elements are primarily concentrated in concretions exposed on the sea-floor. The occurrence mode of concretions and compositional data on interstitial water suggest that metals in the concretions were derived from seawater and suspended particulates, in addition to sediments. Burial of concretions in the sediment pile is accompanied by the alteration of their composition, accumulation of Mn (relative to Fe), and loss of several associated metals.

Role of the biogenic factor in platinum accumulation by oceanic ferromanganese nodules

A complex study of oceanic ferromanganese nodules (FMN) from the abyssal Clarion-Clipperton Fracture Zone and Lamont Guyot (Pacific Ocean) is performed. The concentrations of noble and trace elements are determined by AAS, INAA, and RFA-SR. Furthermore, SEM, and activation autoradiography are applied. Experiments are carried out using Pt, Au, and Ir radionuclides (radioisotope indicator method).

Composition of ferromanganese nodules from Riga Bay (Baltic Sea)

An average sample of ferromanganese nodules from Riga Bay was investigated by analytical electron microscopy coupled with atomic absorption, neutron activation, and ICP-MS methods. It is established that the nodules consist of colloform and poorly crystallized Fe and Mn hydroxides with an admixture of dispersed inclusions of better crystallized particles allowing revealing their mineralogical nature by the microdiffraction method. The major mineral phases are ferroxigite and Fe-vernadite with subordinate magnetite, asbolane, and todorokite. The chemical composition of the nodules is dominated by iron followed by cobalt and lead, while nickel, molybdenum, and tungsten associate with the manganese phase. The concentration of several minor elements in the Riga Bay nodules is slightly lower as compared with their average values for the entire Baltic Sea; some elements such as silver, bismuth, cadmium, niobium, tin, and thallium were never analyzed before.

Patterns of spatial distribution of elements in phosphate-free Fe–Mn Pacific nodule

The distributions of ore elements (Mn, Fe) and 20 chemical “trace” elements in a ferromanganese nodule from underwater Magellan mountains (Pacific Ocean) have been studied with scanning X-ray fluorescence analysis using synchrotron radiation (XRF-SR) with the scanning step of 400 μm. The nodule is characterized by the low phosphorus content (less than 1.0%). The variability of concentrations of the most elements including Mn and Fe from periphery to the nodule center is less than 15%. For all points of a scanning profile, the positive Ce h/Ce h* anomaly is evident, the spread in values being in the range 1.14–1.85. The Fe/Mn-modulus and values of the Ce h/Ce h* anomaly have, as a whole, the negative correlation, however, their imperfect out-of-phase distributions allow one to assume three competing ways for supply Mn into a nodule: from hydrothermal waters, as well as from bulk ocean water and underlying bottom sediment.

A XAFS study on the mechanism of isotopic fractionation of molybdenum during its adsorption on ferromanganese oxides

Due to its potential as a paleoredox proxy, there have been many studies on Mo isotopic fractionation during adsorption onto ferromanganese oxides in seawater. However, the mechanisms of both adsorption and isotopic fractionation are still under debate due to the lack of structural information on the adsorbed species. In this study, XAFS analyses were performed to reveal the mechanism, based on structural information at the molecular level, of Mo isotopic fractionation during adsorption onto ferromanganese oxides. Molybdenum L3-edge XANES and K-edge EXAFS revealed that Mo species adsorbed on the surface of ferrihydrite was a tetrahedrally coordinated outer-sphere complex, while that on δ-MnO2 was an octahedrally coordinated inner-sphere complex. Additionally, it was also revealed that δ-MnO2 was the dominant host phase of Mo in the hydrogenetic ferromanganese nodules from the comparison of their XAFS spectra. Previous studies reported that lighter isotopes of Mo were preferentially incorporated into ferromanganese oxides from seawater. This fractionation can be explained based on the structural difference between tetrahedral MoO42- (=a major species in seawater) and the octahedral species adsorbed on the Mn oxide phase in ferromanganese nodules. In contrast, little change in Mo local structures during its adsorption onto ferrihydrite also suggested the little or no fractionation of Mo isotopes in the presence of Fe hydroxides without Mn oxides. These facts imply that the Mo isotopic composition in ancient marine sediments can distinguish redox boundaries of Fe2+/Fe(OH)3 and of the more oxic Mn2+/MnO2.

Hydrocarbon-derived ferromanganese nodules in carbonate-mud mounds from the Gulf of Cadiz: Mud-breccia sediments and clasts as nucleation sites

More than 500 Fe–Mn nodules were sampled during the Anastasya-01 cruise (TASYO project) along the continental margin of the Gulf of Cadiz (eastern Central Atlantic), at the confluence of the Mediterranean Sea with the Atlantic Ocean, where extensive nodule fields were discovered. Based on wide previous studies that included swath bathymetry, multi-channel and very high-resolution seismic reflection, gravimetry, magnetism and underwater photography surveys, nodules were collected at water depths ranging from 850 to 1000 m, associated with hydrocarbon-derived ankerite and dolomite chimneys and crusts. Thirty six selected samples among the various morphological types were used for the laboratory analysis of physical properties (morphology, colour, surface texture, sphericity, weight and size), mineralogy (XRD, optical and electronic microscopy) and geochemistry (XRF, AAS, ICP-MS, EPMA, GC-MS, S, C and O isotopes). Nodules show a wide range of sizes, densities, weights and morphologies. Nodules are formed of multiple millimetre-thick layers of Fe and Mn oxyhydroxides surrounding the nucleus composed of Early–Middle Miocene plastic marl. The textures developed by the Fe and Mn oxyhydroxides layers are massive, laminated, detrital and mottled to dendritic. Goethite, lepidocrocite, Mn-oxides (7 Å-manganates and 10 Å-manganates), quartz, and phyllosilicates are the main components. Accessory minerals are calcite, dolomite, siderite, rhodochrosite, kutnohorite, pyrite, chalcopyrite, potassium feldspar, zircon, rutile, ilmenite, and chlorite. Fe–Mn carbonates from the siderite–rhodochrosite continuous series are forming part of the marl nuclei. Framboidal, filamentous, and globular textures are observed in Fe–Mn oxides and pyrite suggesting biogenic origin. Nodules show a high mean abundance of Fe (38.6%) moderate Mn (6.0%), and low contents of trace metals and REEs compared to the average content of deep-seabed polymetallic nodules from other oceanic areas. The Mn/Fe ratio ranges from 0.07 to 0.25. The studied nodules hold in their oxide layers hydrocarbons (n-alkanes) derived from marine bacterial activity. Aromatic hydrocarbons in the form of phenanthrene, are also present which is characteristic of mature petroleum. The structure, mineralogy, and chemical composition in the studied nodules are similar to those of diagenetic–hydrogenetic continental margin nodules rather than deep-sea nodules. We suggest that the formation of this type of nodule occurred through a combined diagenetic–hydrogenetic growth process involving fluid venting from deep-seated hydrocarbon reservoirs, bio-mineralization processes, and bottom current erosion.

The Role of Primary-Producer-Mediated Organic Complexation in Regional Variation in the Supply of Mn, Fe, Co, Cu, Ni and Zn to Oceanic, Non-Hydrothermal Ferromanganese Crusts and Nodules

Oceanic, non-hydrothermal ferromanganese crusts and nodules are variably enriched in Mn, Fe, Co, Cu, Ni and Zn. Comparison of the content of these elements in crusts and nodules with the level of primary productivity in the South Pacific Ocean suggests that primary-producer-mediated complexation of several of these elements by organic ligands in solution may contribute to explaining a pattern of distinctive associations observed between compositional variations for these elements in these deposits and variations in the level of primary productivity.

Biomineral nanostructures of manganese oxides in oceanic ferromanganese nodules

Manganese oxides, which are widespread and of great practical importance, are formed and transformed by the active role of microorganisms. Manganese aggregates occur as both crystallized varieties and disordered fine-grained phases with significant ore grade and up to 50–60 vol % of X-ray amorphous components. X-ray amorphous nanosized Mn oxides in Fe-Mn nodules from the Pacific Ocean floor were examined from the standpoint of their biogenic origin. SEM examination showed abundant mineralized biofilms on the studied samples. The chemical composition of bacterial mass is as follows (wt %): 28.34 MnO, 17.14 Fe2O3, 7.11 SiO2, 2.41 CaO, 17.90 TiO2, 1.74 Na2O, 1.73 Al2O3, 1.30 MgO, 1.25 P2O5, 1.25 SO3, 0.68 CoO, 0.54 CuO, 0.53 NiO, and 0.50 K2O. The chemical composition of fossilized cyanobacterial mats within the interlayer space of nodulesis as follows (wt %): 48.35 MnO, 6.23 Fe2O3, 8.76 MgO, 5.05 Al2O3, 4.45 SiO2, 3.63 NiO, 2.30 Na2O, 2.19 CuO, 1.31 CaO, and 0.68 K2O is direct evidence for participation of bacteria in Mn oxide formation. This phase consists of mineralized glycocalix consisting of nanosized flakes of todorokite. Native metals (Cu, Fe, and Zn) as inclusions 10–20 μm in size were identified in ferromanganese nodules as well. The formation of nativemetals can be explained by their crystallization at highly reducing conditions maintained by organic matter.

Formation particularities of hypergene ferromanganese nodules: Far East Russia and Vietnam

Ferromanganese nodules (pisolites) form accumulations in basal layers of Pliocene-Quaternary clayey sections of Far East Russia and Vietnam. They are composed of minerals that are in common for both these regions (authigenic vernadite, feroxyhyte, goethite, halloysite, and terrigenous quartz) and minerals that are characteristic of either the northern (authigenic hollandite, lithiophorite, and bernessite) or southern (authigenic alumophorite, lepidocrocite, ferrihydrite, gibbsite, and terrigenous ilmenite) regions. Pisolites are considered to be microbial colonies with Mn and Fe oxides frequently forming biomorphs. The growth of the colonies was accompanied by dying off and mineralization of microorganisms successively from the central toward the peripheral parts of the nodules. The formation of metalliferous pisolites was linked to the oxidizing geochemical barrier developed at the interface between compact sedimentary clays and the underlying porous readily permeable weathered products of basalts.

A new concept of pedogenic nodule formation in landscapes of the Russian Far East

The typification of ferromanganese nodules (FMN) formed in subaqueous and subaerial settings and in residual materials, as well as FMN localization in various sediments and soils, is discussed. The genetic diversity of morphologically similar FMN and the transformation of FMN-bearing complexes with changes in landscapes have been established.

Tectonic types of oceanic abyssal basins and related potentially economic fields of ferromanganese nodules

Tectonic typification of the abyssal basins of the Atlantic, Indian, and Pacific oceans is proposed. Six types of basins are recognized: perispreading, pericontinental, central thalassogenic, intermontane abyssal, interfault, and thalassosyneclise. The tectonic diversity of the basins and their systems reflects significant regional tectono-geodynamic features of the oceanic lithosphere. Basins of the first type are inherent to the Atlantic Ocean; of the second and third types, to the Indian Ocean; and of the fourth to sixth types, to the Pacific. In the Atlantic Ocean, the basins are spatially and paragenetically conjugated with the mid-oceanic ridge. Beyond the Atlantic, a similar situation is characteristic of the southern Indian Ocean only. Hence, differentiated energetic models of deep geospheres are required. The relations of potentially economic fields of ferromanganese nodules to tectonic types of abyssal basins are discussed. The largest fields with respect to both dimensions and reserves are confined to interfault and intermontane abyssal basins. The fields localized in central thalassogenic basins are second in importance. The perispreading and pericontinental basins are the least promising in this respect. Along with other criteria, tectonic analysis should be taken into consideration in the future development of these valuable mineral resources.

Nodule morphology and growth model

A recent article in PNAS by Asikainen and Werle (1) reports on the occurrence and morphology of ferromanganese nodules found in a New Hampshire lake. The authors offer data on the shapes, banding, composition, and distribution of the nodules and crusts. They also state that my paper (2) claims that the morphology of such … *E-mail: bernie.boudreau{at}dal.ca

Reply to Boudreau: Morphologic expression of ferromanganese nodules

The statement that nodule formation, especially morphology, can be predicted by the Boudreau diagenetic model led us to state that “diagenetic models that claim to predict nodule growth rate and morphologies from elemental concentrations (1) are not verified by our data” for Second Connecticut Lake (SCL), New Hampshire (2). Comments on metal gradients and elemental concentration of manganese (Mn) and iron (Fe) required for accretion and morphologic expression of ferromanganese nodules are in Boudreau's original paper (3). Yet, in his letter (4), Boudreau writes that elemental (metal) concentration is not discussed (1, 3).

Geochemistry of the authigenic ferromanganese ore formation in sediments of the Northeast Pacific Basin

Authigenic ferromanganese formations in sediments from two horizons (0–10 and 240–250 cm) located in the low/high bioproductive transitional zone of the Pacific Ocean were studied. In addition to the compositionally different two types of micronodules, crusts and ferromanganese nodules were detected in the surface horizon (0–1 cm). Three size fractions (50–100, 100–250, and 250–500 μm) of manganese micronodules were investigated. In terms of surface morphology, color, and shape, the micronodules are divided into the dull round (MN1) and angular lustrous (MN2) varieties with different mineral and chemical compositions. The dull MN1 are enriched in Mn and depleted in Fe as compared with the lustrous MN2. The Mn/Fe value in the dull MN1 varies from 13 to 14. Asbolane-buserite and birnessite are the major manganese minerals in them. The lustrous MN2 is mainly composed of vernadite with Mn/Fe = 4.3–4.8. Relative to the dull MN1, fraction 50–100 μm of the lustrous MN2 is enriched in Fe (2.6 times), W (1.8), Mo (3.2), Th (2.3), Ce (5.8), and REE (1.2–1.8). Relative to counterparts from the dull MN1, separate fractions of the lustrous MN2 are characterized by a greater compositional difference. For example, increase in the size of micronodules leads to decrease in contents of the following elements: Fe (by 10 rel %), Ce (2 times), W (2.1 times), Mo (2.2 times), and Co (1.5 times). At the same time, one can see increase in contents of other elements: Th and Cu (2.1 times), Ni (1.9 times), and REE (1.2–1.6 times). Differences in the chemical and mineral compositions of MN1 and MN2 fractions can be related to alternation of oxidative and suboxidative conditions in the sediments owing to the input of a labile organic matter, which serves as the major reducer, and the allochthonous genesis of MN2.

Accumulation and fractionation of trace elements in soil ferromanganese nodules of different size

The concentrations and distribution of bulk and mobile species of trace elements were investigated in various size fractions of ferromanganese nodules from bleached meadow-brown soils. It was shown that the enrichment factor of trace elements increases during the growth of nodules; however, the character of element accumulation appeared to depend on the nature of the element. The nodules intensely accumulate Mn, Co, Ni, and Pb and, to a lesser extent, Cu and Mo. The process of trace element uptake by the nodules is most contrasting in the middle part of the soil profile. The nature of trace element concentration by soil nodules is rather complex and requires further special investigations.

High-sensitive measurement of uranium LIII-edge X-ray absorption near-edge structure (XANES) for the determination of the oxidation states of uranium in crustal materials

The uranium LIII-edge XANES spectra for natural rocks at the concentration range of 0.96–124 mg kg−1 were measured using a log spiral bent crystal Laue analyzer (BCLA) combined with a multi-element Ge detector. It was found that the quality of the XANES spectra using the BCLA was greatly improved due to a reduction of interfering fluorescence from major components such as Rb and Sr. The ratio of signal to background intensities in the U LIII-edge XANES spectra increased by a factor of 2.9–17 with the use of the BCLA, which greatly enhanced the detection limit for the speciation of the oxidation states of U or the U(IV)/U(VI) ratio of natural samples. In addition, it was demonstrated that the fluorescence XANES method coupled with the BCLA enable determination of the speciation of U for various natural samples such as acidic igneous rocks, ferromanganese nodules, sediments, and some sedimentary rocks such as shale and limestone.

Accretion of ferromanganese nodules that form pavement in Second Connecticut Lake, New Hampshire

We discovered ferromanganese nodules that measure up to 46 cm in diameter with stromatolitic growth patterns in the western central near-shore portion of Second Connecticut Lake, Pittsburg, New Hampshire. They occur as four distinct morphotypes: irregular laminated convex plates that form concentric rings around a nucleating center ("domed-plate"), continuous pustular pavements that extend >10 m2 ("pustular"), nonlaminated and nonnucleated masses with pebbles scattered throughout the matrix ("lattice"), and small nonnucleated laminated structures >2 cm ("cup") in water depths between 5 and 12 m. An estimated growth rate of 26 mm/100 years was determined from oxide deposits on datable debris. X-ray fluorescence showed an elemental composition comparable with that of nodule structures in other lakes. These sedimentary structures, the first seen in any of the six New England states, are the most morphologically distinct and varied lacustrine ferromanganese nodules known so far.

Ferromanganese deposits from different regions of the Atlantic

Results of the study of Fe–Mn deposits (FMD) from different regions of the Atlantic obtained in several expeditions of research vessels of the Russian Academy of Sciences in 2004–2006 are presented. Materials were gathered at dredging stations during these geological expeditions under the supervision of S.G. Skolotnev. Ferromanganese nodules were dredged at three stations during Cruise 16 of the R/V Akademik Ioffe (Fig. 1). The first and second stations were set up at the southern foothill of the Cape Verde Rise (site 1), where the sedimentary cover is 550 m thick. The study region incorporates the Elena Seamount and other protrusions. Dredging of the northern slope of the Elena Seamount within the depth interval of 4800–4200 m at station 16-03 ( 11°03.5 ′ N, 26°37.1 ′ W) yielded more than 15 kg of nodules with similar structural and textural characteristics, high density of ore material, and rusty brown color. Five nodule samples were selected for the analysis. In one large nodule (sample 16-03/36), we analyzed the surface film (sample 16-03/36a), the central part of the outer ore layer 40 mm thick (sample 16-03/36b), and the inner ore layer 15–20 mm thick (sample 16-03/36c), which was clearly separated by interlayers of clayey material. The nodule core is composed of a light lithified clayey substance. The boundary between the outer and inner layers is seen clearly on the cross section (Fig. 2). Data on the chemical analysis (Table 1) showed sharp distinctions in the composition of ore material between samples from the outer layer (16-03/36a, 16-03/36b) and inner layer (16-03/36c) enriched in Mn (Mn/Fe = 1.39). Bar charts (Fig. 3) demonstrate variations in the content of trace elements (in ppm) recalculated to the ore phase (Mn + Fe). One can see that the inner part is enriched in Cu and especially Ni, the content of which reaches 3.4%. It is likely that the nodules include two generations of ore matter formed at different stages and under different conditions.