ALBERT

Description: Deep sea manganese nodules from the Central Pacific Basin are mainly composed of 10Å manganite and d-MnO2 Two zones equivalent to the minerals are evidently distinguishable according to their optical properties. Microscopic and microprobe analyses revealed quite different chemical compositions and textnral characteristics of the two zones. These different feature of the two zones of nodules suggest the different conditions under which they were formed. Concentrations of 11 metal elements in the zones and inter-element relationships show that the 10Å manganite zone is a monomineralic oxide phase containing a large amount of manganese and minor amounts of useful metals, and that the d-MnO2 zone which is apparently homogeneous under the microscope is a mixture of three or more different minerals. The chemical characteristics of the two zones can explain the variation of bulk composition of deep sea manganese nodules and inter-element relationships previously reported, suggesting that the bulk compositions are attributable to the mixing of the 10Å manganite and d-MnO2 zones in various ratios. Characteristic morphology and surface structure of some types of nodules and their relationships to chemistry are also attribut able to the textural and chemical features of the above mentioned two phases. Synthesis of hydrated manganese oxides was carried out in terms of the formation of manganese minerals in the ocean. The primary product which is an equivalent to d-MnO2 was precipitated from Mn 2+ -bearing alkaline solution under oxigenated condition by air bubbling at one atmospheric pressure and room temperature. The primary product was converted to a l0Å manganite equivalent by contact with Ni 2+, Cu 2++ or CO2+ chloride solutions. This reaction caused the decrease of Ni2+, Cu2+ or CO2+ concentrations and the increase of Na+ concentration in the solution. The reaction also proceeded even in diluted solutions of nickel chloride and resulted in a complete removal of Ni2+ from the solution. Reaction products were exclusively 10Å manganite equivalents and their chemical compositions were very similar to those of 10Å manganite in manganese nodules. The maximum value of(Cu+Ni+Co)/Mn ratio of 10Å manganite zones in manganese nodules is 0.16, and the Ni/Mn ratio of synthetic 10Å manganite ranges from 0.15 to 0.18 with the average of 0.167.

Description: The major and some of the minor constituents and the rate of accumulation of manganese nodules in the western North Pacific were determined. Manganese concentration in the nodules ranged from 20 to 30 per cent in the acid soluble fraction. As to the rare earth concentration, enrichment of cerium was observed in the manganese nodule as compared with that in shales or sea water. Thorium to uranium ratio in the nodule ranged from 9.4 to 14.3, which was very much higher than that in sea water. From the distribution of excess ionium, excess protactinium and Io/Th ratio, a rate of accumulation of 7 mm per million years was obtained with the surface layer of several mm in thickness of the JEDS-4-E4 nodule.

Description: Manganese oxide crusts similar to those reported from the Mid-Atlantic Ridge rift valley by Scott et al., 1974 (https://doi.pangaea.de/10.1594/PANGAEA.848726) were dredged at two sites near the Galapagos spreading axis on ocean floor estimated from magnetic anomalies to be 2.4 and 0.3 m.y. old. Compared to the typical ocean-floor manganese deposits attributed to precipitation from seawater, the 2-6 cm thick manganese crusts reported here exhibit very low Fe/Mn and low 232Th/238U ratios, as well as lower transition metal and higher manganese concentrations. The manganese crusts were deposited several orders of magnitude faster than the more common hydrogenous nodules; this fact together with other geochemical characteristics and the geophysical environment suggests the manganese deposits reported here are of hydrothermal origin.

Description: The major and minor element compositions of a suite of abyssal sea-floor ferromanganese nodules and associated sediments from the eastern central Pacific have been used to examine inter-element relationships and the mineralogy of the nodules, the relationship between the composition of nodules, and their associated sediments and regional variations in composition with respect to likely modes for formation of such deposits. Apart from Mn and Fe, significant proportions of the total Ti, Ca, Mg, K, Ba, Sr, Th and Y and almost all the P, As, Ce, Co, Cu, Mo, Ni, Pb, Zn and Zr are present in the oxide fractions of the nodules. The Mg, Ba, Cu, Mo, Ni and Zn contents are significantly correlated with the total Fe content. Nodules from the northeastern tropical Pacific have Mn/Fe ratios highter than those in the oxide fractions of their associated sediments, todorokite as the principal Mn phase and relatively high concns of minor elements associated with Mn. Nodules from the south central Pacific have Mn/Fe ratios similar to those in the oxide fractions of the associated sediments, {delta}-MnO Sub(2) as the only Mn-phase, and relatively high concns of minor elements associated with Fe. There appears to be a smooth gradation in composition in the tropical Pacific between these 2 end members. The retional compositional variation is interpreted as a reflection of different sources of metals for, and different growth mechanisms of, sea-floor nodules. The oxide precipitate from sea water consists of {delta}-MnO Sub(2), has a relatively low Mn/Fe ratio and minor element contents related to the total Fe and Mn({delta}-MnO Sub(2)) content. The oxide precipitate forming in areas of very low sedimentation as a result of diagenetic remobilisation in the surface sediment consists of todorokite, and has a high Mn/Fe ratio and enhanced metal content in the Mn-(todorokite) phase. Available information on the morphology and compositional variation of individual nodules from the tropical Pacific corroborates these contrasting metal sources and suggests that they can be resolved on the scale of an individual oxide concretion.

Description: Bulk composition of ferromanganese nodules from the pelagic environment of the Pacific Ocean is apparently related to nodule-growth rate, sediment-accumulation rate, and biologic productivity in the overlying seawater. Nodules with a high Mn/Fe ratio and high Ni and Cu concns tend to occur in areas where primary productivity in the surface layer of the ocean is high and the sediment accumulation rate low. They may have a Mn/Fe ratio as low as one and accrete at rates as low as 1 mm/10 M yrs. Nodules with a larger Mn/Fe ratio apparently have growth rates that are greater by as much as a factor of 10.

Description: Analyses of small samples extracted from different parts of a single manganese nodule have been reported by several investigators, clearly documenting the belief that a nodule is not homogeneous chemically, as a rule. The same sort of evidence has been gathered by use of the X-ray macroprobe and electron microprobe analyses. The X-ray probe work has shown clearly that chemical variations within a nodule can be correlated with optically recognizable mineral,and therefore optical study can tell much about chemical variations and obviate much probe analysis. As we have reported many times, optically anisotropic crystalline todorokite and birnessite contain the bulk of the Mn, Ni, and Cu in any nodule whereas optically isotropic and X-ray amorphous oxides contain most of the Fe and Co in the same nodule.

Description: Manganese nodules and associated sediment from the equatorial North Pacific have been examined to ascertain relations between nodule abundance, texture, and composition, and sediment composition, lithology and acoustic stratigraphy. Nodules are most abundant in areas where the uppermost acoustically transparent layer of sediment is less than approximately 15 m thick. Abundance drops off sharply in areas where this acoustic unit is thicker than 20 m. Nodules have average Zn/Mn and Co/Mn ratios which are approximately the same as these ratios for the component of sediment soluble in hydroxylamine hydrochloride-acetic acid. The relations between Cu and Mn and Ni and Mn in the sediment are also approximately the same as in nodules, but only for those nodules which have a smooth surface texture. Granular nodules have relatively more Ni and Cu. Antimony in nodules, similar to Ni, Cu, and Zn, is strongly correlated with Mn, whereas Co, Hf, Th, and U are strongly correlated with Fe. The insoluble component of sediment has a uniform composition which is similar to the composition of terrigenous shale. This similarity holds for the major oxides as well as for Co, Cr, Zn, Hf, Sb, Th, U, Sc, Cs, Rb, and Ta.

Description: Atlantic manganese nodules and encrustations are most abundant in areas of slow sedimentation beneath the carbonate compensation depth or where currents inhibit sediment accumulation. They principally contain the minerals todorokite and ?MnO2, which are selectively concentrated into nodules and encrustations, respectively, and which show an environmental differentiation thought to be related to redox potentials. Excluding the continental margins, todorokite is most abundant in deepwater deposits. Mineralogical differences between nodules influence their chemical compositions, Ni and Cu being most abundant in samples rich in todorokite and Co in those rich in ?MnO2. Chemically, the deposits differ from those in other major oceans principally in their higher Fe and lower Ni and Cu contents, which may be due to higher rates of supply of Fe to the deposits than those in the other oceans. Regional variations occur in the concentrations of several elements, Mn, Ni, and Cu being enriched in deepwater deposits from areas of slow sedimentation between the Mid-Atlantic Ridge and the continental margins and Co being enriched in some deposits from elevated localities. These variations are thought to be due to variation in the sources of the elements concerned and in the depositional environment.

Description: Manganese nodules from the Scotia Sea and Pacific Ocean sectors of the Southern Ocean display regional differences in chemical and mineralogical composition. Mn/Fe and todorokite/delta-MnO2 ratios decrease southeasterly from the Southwestern Pacific Basin to the Drake passage-Scotia Sea. Relative to Mn, the greatest enrichments of Co, Ti, V, Zn, Mo and Sn occur in Drake Passage-Scotia Sea nodules, while Ni and Cu are most enriched in the Southwestern Pacific Basin. Manganese mineralogy is directly related to the Mn/Fe ratio, so that todorokite rather than delta-MnO2 predominates when high manganese vs iron contents are found. Trace metal contents are also related to mineralogy, with high values of Ni, Cu, Zn and Sn, and low values of Co, Ti, V and Mo associated with high todorokite contents. Nodules having indistinct zeolitits/vesiculite nuclei tend to have Mn/Fe and todorokite/delta-MnO2 ratios significantly higher than average for the region in which they are found, whereas ferromanganese oxide fragments dredged from submarine rock surfaces usually have Mn/Fe and todorokite/delta-MnO2 ratios lower than regional average.

Description: Shebandowan Lakes, Ontario, are the site of at least 49 shallow (2-12 m) ferromanganese concretion deposits, widely distributed throughout the 48 km of the watercourse. X-ray diffraction and Mossbauer methods have revealed the presence of goethite in some of the concretions. Chemical analyses of the acid soluble portions of 72 samples gave an average composition of 43.1% Fe and 5.65% Mn with a low content of trace elements. The Shebandowan concretions are among the richest in iron of lake concretions reported, possibly because only the acid soluble portion was analysed. Their low content of trace elements suggests rapid growth rates and a relatively young age. A positive correlation was found between Mn and K, Ca, Mg, Cu, Ni, and Co and the relationship between the last three and Mn was deemed significant. Zn was independent of association with either Mn and Fe, probably due to the presence locally of zinc sulphide deposits. Analyses of lake bottom and influent waters suggested that frequent resampling of the sites would be required throughout the year to permit meaningful interpretation of the effect of water composition of concretions. Analyses of sediment cores from 20 concretion sites indicated an upward increase in Fe and Mn and in the Mn/Fe ratio, consistent with the model of upward migration of the elements, where Mn is more mobile than Fe. This study concludes that a considerable proportion of the elements have been supplied to the Shebandowan concretions via the diagenetic process; generally a minor fraction of the elements has been abstracted directly from the superjacent water.

Description: The cores and dredges described in this report were taken on the KH-72-2 Expedition in October-December, 1972 by the Ocean Research Institute, University of Tokyo from the R/V Hakuho Maru. A total of 21 cores and dredge sites have been recovered.

Description: Information on possible resource value of sea floor manganese nodule deposits in the eastern north Pacific has been obtained by a study of records and collections of the 1972 Sea Scope Expedition.

Description: Information on possible resource value of sea floor manganese nodule deposits in the Pacific has been assessed by Deepsea ventures Inc, from the collection of manganese nodules and crusts obtained during past research vessels' cruise from the Scripps Institution of Oceanography.

Description: The object of the detailed investigations was an unusual material collected in the region of the Southern Basin of the Pacific Ocean floor, with features of intense manifestation of volcanic processes and subsequent hydrothermal alterations. These processes to a significant degree transformed the ferromanganese nodules and the pelagic sediments, causing the development of a new type of oceanic manganese mineralization.

Description: It is the purpose of this chapter to present information available at the time of publication on the internal features of manganese nodules, to offer genetic interpretations of these features, and to suggest new lines of research. To judge from the limited data available on ocean floor crusts rich in manganese and iron (see, for example, Aumento et al., 1968, doi:10.1594/PANGAEA.862565 ), much of what is learnt about nodules may be applied eventually to an understanding of the origin of these more continuous masses. A genetic relationship between these two is likely.

Description: Manganese nodules from six Pacific Ocean sites contain two chief oxide components which can be distinguished by both optical and X-ray diffraction methods. Optically coordinated electron microprobe spot analyses reveal that copper and nickel are concentrated in the manganese-rich crystalline oxides (birnessite and todorokite) while cobalt is concentrated in the iron-rich amorphous oxides. In the nodules studied the maximum nickel content in the crystalline material is 3.6%, while the maximum copper content is 2.95%. The highest cobalt content found in the amorphous material was 0.74%. Large variations in concentrations were found within individual nodule layers as well as from one layer to another. Most of the variations cannot be accounted for by admixed nodule components. The variations cannot be distinguished by any optical or X-ray diffraction criteria and are probably controlled by the availability of the elements during primary deposition. There does not appear to be any linear interelement relationship between concentrations of the major elements (Mn and Fe) and the minor elements (Ni, Cu and Co). Linear relationships that have been reported in the past must be interpreted with care, for crystalline oxides and amorphous oxides may have been mixed in varying amounts during the sampling. In view of the different element associations in the crystalline and the amorphous oxides, the main factor for controlling bulk chemical analysis of a particular nodule appears to be the ratio of crystalline to amorphous material in the nodule. NSF-IDOE support of this research is acknowledged with thanks.

Description: Cruise Mn-74-02 of the R/V MOANA WAVE was the second part of the field work of the NSF/IDOE Inter-University Ferromanganese Research Program in 1974, and we gratefully acknowledge the support of the office for the International Decade of Ocean Exploration and the Office of Oceanographic Facilities and Support. This program was designed to investigate the origin, growth, and distribution of copper/nickel-rich manganese nodules in the Pacific Ocean. The field effort was designed to satisfy sample requirements of the fifteen principal investigators, while increasing general knowledge of the copper/nickel-rich nodule deposits of the equatorial Pacific. This report is the second of a series of cruise reports designed to assist sample requests for documented nodules, sediment, and water samples so that laboratory results can be realistically compared and related to the environment of nodule growth. Nodule samples and bathymetric and navigational data are archived at the Hawaii Institute of Geophysics, University of Hawaii. Bulk chemical analyses of nodules and reduction of survey data were carried out at Hawaii. Sediment cores were stored at the University of Hawaii and at Scripps Institution of Oceanography. The SIO analytical facility provided stratigraphic data on sediment chemistry.

Description: In 1975 Washington State University was contracted by the U. S. Geological Survey to conduct a study of manganese nodules collected during cruises of the DOMES project of NOAA. The nodule research was to be restricted to problems related to DOMES objectives and was not to include a study of problems of nodule distribution and origin. The project was to be coordinated with mineralogical and chemical investigations carried out simultaneously in Geological Survey laboratories. This report concerns only the RP6-OC-75 samples. The body of the report describes the nature of the major types of surface features of nodules and includes numerous illustrations of of typical nodules. To provide a wider coverage of nodule types in the collection, and to record some of the gross physical data on the nodules, an illustrated Appendix is also included.

Description: Study of the occurrence and physical and chemical character of manganese nodules collected in box cores in DOMES Sites A, B, and C indicates that virtually all nodules lie at the sediment-water interface. Buried nodules are rare. Nodules seem to be smaller and have smoother surfaces at Site A than at Sites B and C. Site C nodules are predominantly 2-6 cm in size and have smooth tops and granular bottoms. Nodules from all sites show non-uniform contents of Mn, Fe, Ni and Cu within individual box cores. The greatest variations were found in box cores from Sites A and C. Mn, Ni, and Cu are generally covariant whereas Fe content is antithetic to Mn content. Large variations in metal content are generally due to differences in oxide mineralogy but some variation is related to clay content. Large nodules tend to be relatively low in Mn, Ni, and Cu. Site B nodules have the highest mean values for Mn, Ni, and Cu and the lowest mean Fe content. Site C nodules and Site A nodules have the same Mn content, but Site C nodules are richer in Ni and poorer in Fe than Site A nodules.

Description: The GEORSTOM III CENTRE expedition on the R/V Noroit surveyed the Coral Sea around the New Hebrides Islands and the Erromango Plateau from 17 until 26 October 1975. This report offers a description of the dredging sites, the macroscopic and microscopic determinations of samples, the chemical analyzes of rocks, the electron microprobe and micropaleontological determinations, the photographic plates and the preliminary conclusions.

Description: The Marine Minerals Database contains geochemical analyses and auxiliary information on present-day marine deposits of primarily ferromanganese nodules and crusts. Some data for heavy minerals are also included. Sources of ferromanganese analyses include the historic Scripps Institution of Oceanography (SIO) manganese nodule analysis file compiled under the direction of Jane Frazer and Mary Fisk.

Description: The plateau is a foundered continental block, and lies at an average depth of 2000-3000 m. On the plateau the dominant fault direction is NW to WNW, an ancient strike direction on the Australian continent. The western margin probably formed as a series of NE-trending rifts and NW-trending transforms during Late Jurassic breakup. Canyons cut the western margin, and some of these appear to be fault-bounded. One such fault forms the northern margin of a major NW-trending feature, the Wilson Spur. This appears to be a transform fault and perhaps extends across the abyssal plain as far as the eastern end of the Java Trench. Seismic profiles suggest that, at the trench, it separates thrust-faulted continental crust to the east from oceanic crust to the west. This could explain the eastern termintion of the deep part of the trench. The bathymetric depression of the Roti Basin, which lies southeast of the Java Trench, links the trench to the Timor Trough. The Argo Abyssal Plain slopes gently southward, with water depths ranging from 5000 m near the Java Trench to 5730 m in the south. Oceanic basement varies from smooth to hummocky and irregular, and is overlain by about 4000 m of acoustically semi-transparent Late Jurassic and Cretaceous sediments, that is in turn unconformably overlain by 200 m of layered Tertiary sediment. Bottom samples from the outer Scott Plateau show that Callovian breakup was preceded by a period of basic volcanism and shallow marine sedimentation, that restricted shallow marine conditions followed in the Late Jurassic, and that bathyal carbonate sedimenation prevailed by the Late Cretaceous (Campanian). Quaternary marls cored on the northern Scott Plateau straddled the Pleistocene-Holocene boundary, and siliceous oozes cored on the southern slope of the Java Trench contain nannofossils which, below a few decimetres, are older than late Pleistocene. The Java Trench cores indicate that the calcite compensation depth was apparently between 5420 and 5700 m in the early or midel Pleistocene, and is above 4950 m now. The Scott Plateau cores indicate that the present calcite compensation depth in the region lies below 3290 m. On the Scott Plateau Holocene sedimentation rates are about 5 cm/1000 years, but in the Java Trench they are much lower. Manganese oxide crusts and nodules were recovered from the Scott Plateau, but their content of valuable metals was low.