Grains of Nonferrous and Noble Metals in Iron–Manganese Formations and Igneous Rocks of Submarine Elevations of the Sea of Japan

Iron–manganese formations and igneous rocks of submarine elevations in the Sea of Japan contain overlapping mineral phases (grains) with quite identical morphology, localization, and chemical composition. Most of the grains conform to oxides, intermetallic compounds, native elements, sulfides, and sulfates in terms of the set of nonferrous, noble, and certain other metals (Cu, Zn, Sn, Pb, Ni, Mo, Ag, Pd, and Pt). The main conclusion that postvolcanic hydrothermal fluids are the key sources of metals is based upon a comparison of the data of electron microprobe analysis of iron–manganese formations and igneous rocks dredged at the same submarine elevations in the Sea of Japan.     

Manganese metalliferous sediments of the Deryugin Basin (Sea of Okhotsk): Chemical composition and geological setting

This paper reports the results of an investigation of the chemical composition and distribution of manganese-rich metalliferous sediments in the Deryugin Basin. They compose an upper sedimentary layer up to 30 cm thick within a strip up to 40 km wide and 180 km long in the central part of the basin along the East Deryugin suture zone bounding the Deryugin sedimentary basin to the east. The sediments are enriched relative to the regional background composition in Mn (by a factor of 35); Au; Ni; Zn; Co (by a factor of 3–5); and, locally, in Mo, V, Ba, Cu, Pb, and Hg. It was supposed that their formation was controlled by several processes: precipitation of Mn and some other trace elements from hydrothermal plumes of seawater that occasionally form above submarine hot vents in the northern part of the basin, precipitation from anoxic bottom waters at the eastern boundary of the Deryugin sedimentary basin, and early diagenetic migration of Mn into the surface sediments.     

The REE species and their distribution in ferromanganese crusts in the Sea of Japan

Polished sections of ferromanganese crusts on underwater rises in the Sea of Japan were studied with a JXA8100 microprobe analyser. Mineral phases of REE have been detected. They have Ln₂O₃ chemical composition, where Ln is La–Ce–Pr–Nd, La–Ce–Nd, or, much more rarely, La–Ce and La–Ce–Pr. With regard to the same chemical composition of REE grains in the ore crusts and basalts from Medvedev Volcano, it has been concluded that these REE were supplied during postvolcanic gas–hydrothermal processes.     

Petrogeochemistry and Ore Mineralization of Sericite–Quartz Schists of the Southern Slope of the Kashevarov Bank (Sea of Okhotsk)

Oceanology - Data on the structure and chemical and mineral composition of sericite–quartz schists of the southern slope of the Kashevarov Bank of the Sea of Okhotsk are presented. The...     

The specifics of ferromanganese ore formation on the submarine Vityaz’ Ridge (Pacific slope of the Kuril island arc)

We present data on the location, chemical composition, and contents of trace elements in thin ferromanganese crusts at two sites of the submarine Vityaz’ Ridge: Diana and Bussol’ test grounds. The crusts abound in inclusions of grains of nonferrous (Cu, Zn, Pb, Sn, Ni, W) and noble (Au, Ag, Pd, Pt) metals in the form of native elements, sulfides, sulfates, oxides, or intermetallic compounds. The crusts at the Diana test ground contain mainly grains of nonferrous-metal minerals, and those at the Bussol’ test ground, mainly noble-metal minerals. There are also sites with Ni-rich (up to 3.5%) manganese crust. A detailed study of the ore crusts from the Vityaz’ Ridge showed that they are probably at the initial stage of formation.     

Development of forecasting technologies for meteorological support of the Sochi-2014 Winter Olympic Games

In February–March 2014 the Winter Olympic Games will be held in Sochi. Sharp weather contrasts and high spatiotemporal variability are typical of the region of the Sochi-2014 Games. The complex mountain terrain and the intricate mixture of marine subtropical and Alpine conditions make the weather forecasting in this region extremely challenging. Although all lead times of the forecast are important for the Games, primary needs for these sport events are associated with the nowcasting and the short-range weather forecasting. The complexity of the Sochi region stimulates the development of high-resolution mesoscale modeling as a backbone of the Olympic meteorological services. Presented are the main branches of the current research in this area carried out in Roshydromet.     

Ferromanganese Crusts in the Central Basin,Sea of Japan

The paper presents a comparative analysis of ferromanganese crusts and concretions (FMC) recovered during the dredging of 14 seamounts in the Central Basin, Sea of Japan. The major rock-forming elements in FMC are Mn, Fe, and Si. In terms of the Mn content, the studied 53 samples are divided into four groups: (1) less than 10% (given than concentrations of 2–8% are lacking); (2) 10?25%; (3) 25?42%; and (4) 42?63%. The (Mn + Fe)/Si ratio increases from group 1 to group 4, and average value in them is 1.6, 2.5, 6.7, and 70.7, respectively. Taking Fe/Si and Mn/Si values into consideration, concretions of these groups belong to the following varieties: (1) ferrosiliceous; (2) mangano-ferrosiliceous; (3) siliceous-ferromanganese, and (4) manganiferous. The highest concentration of nonferrous metals is observed in FMC of groups 2 and 3. Their concentration is slightly lower in group 4 and very low in group 1. The internal structure of FMC in these groups is variable, suggesting their different formation settings. Crusts of group 1 were formed during the precipitation of Mn from a hydrothermal plume on the older ferrosiliceous crusts. Crusts of groups 2 and 3 were likely formed by the diffuse percolation of Mn-bearing hydrothermal solutions along fractures and weakened zones in volcanic rocks, with their subsequent cementation by manganiferous hydroxides from sedimentary or volcaniclastic deposits on seamounts. Crusts of group 4 were formed at sites of the hydrothermal solution discharge on the seafloor. FMC of different groups are recovered during the dredging of most volcanic seamounts in the Central Basin (Sea of Japan). Since the dredging is accomplished at a depth interval of a few hundreds of meters, the detection of concretions of a certain type is governed by the distance to the nearest hydrothermal source.     

Precious and nonferrous metals in the ferromanganese crusts of the central Sea of Okhotsk

Thin mineral grains of nonferrous and precious metals (Ag, Au, Cu, Ni, Pb, Sn, Zn, Sb, Ti, W, Mo, and Ce) were revealed for the first time by SEM and microprobe studies of polished sections of iron-manganese crusts from the Sea of Okhotsk. The metals form native and intermetallic compounds; less frequently they form mineral oxides or sulfides. The conclusion was drawn that the main part of the native minerals represents a mechanical admixture in the ferromanganese crusts.