T. G. Kuz’mina

Lithological and Geochemical Characteristics of Recent and Quaternary Sedimentation in the Arctic Ocean

This paper addresses some problems concerning the geologic activity of sea ice and icebergs, as well as the influence of continental and shelf glaciations on the sedimentation in the Arctic Ocean during Recent and Quaternary times. Seasonal and circumcontinental zoning is clearly manifested in the sedimentation. The role of glacial material in the modern and older sediments was estimated. Mathematical statistical methods were employed for the reliable stratigraphic subdivision of Quaternary sequences and determination of main factors controlling their chemical composition. Silica content was proposed as an optimal parameter for the lithochemostratigraphic subdivision of Quaternary sediments.

Mineralogical and geochemical zoning of sediments at the Semenov cluster of hydrothermal fields, 13°31′-13°30′ N, Mid-Atlantic Ridge

New material from eight columns recovered during Cruise 32 of the R/V Professor Logachev in 2009 was used to explore the lithological facies, biostratigraphy, mineralogy, and geochemistry of sediments from the northwestern (active) and eastern (inactive) hydrothermal vent fields of the Semenov cluster. Mineral types of sediments were distinguished, and a general scheme was proposed for the vertical structure of the hydrothermal-sedimentary sequence overlying massive sulfide ores. It was found that the ore-bearing sediments exhibit a vertical zoning in the distribution of mineral assemblages, which are controlled by oxygen activity. The mechanisms of the formation of atacamite, CuCl2 · 3Cu(OH)2, which is a widespread mineral in red iron-oxide bodies replacing sulfides (gossans), were evaluated.

Multielement determination of the composition of sulfide ores using X-ray fluorescence analysis

The potentials of the multielement X-ray fluorescence analysis of sulfide ores from one sample are studied. Using cluster analysis, sulfide ores are divided into four groups; within each group, the ores are similar in chemical composition and matrix effects. Calibration equations are obtained for each group. The performance characteristics of the determination results are evaluated.

Mineral Associations of the Lost Village and Lost City Hydrothethermal Fields in the North Atlantic

During the 50th cruise of R/V Akademik Mstislav Keldysh, on the south slope of the Atlantis massif (30°07′N; the Middle Atlantic Ridge), an inactive hydrothermal field named the Lost Village was discovered. This new field was formed of light carbonate rock and was located near the active Lost City hydrothermal field. The mineralogical associations of these fields were studied. A conclusion about the participation the ocean water in the changing of the carbonate composition of the inactive hydrothermal field was reached.

Chemical composition of surface sediments of the White Sea

Contents of major elements in surface sediments of the White Sea were determined by the X-ray fluorescence method. Application of the statistical analysis (principal component method and cluster analysis) made it possible to divide the sediments into more or less homogeneous seven groups with different chemical and grain size compositions. In general, the groups corresponded to sediment lithotypes based on the classification elaborated at the Shirshov Institute of Oceanology, Russian Academy of Sciences. Contents of Si and Al are controlled by the ratio of sand-silt and pelite fractions, while variations in the content of Mn (and Fe in part) are governed by the redistribution of elements in the course of redox processes of early diagenesis.

Sedimentation in the submarine Shirshov Ridge area (Bering Sea) during the last 180–185 ka (Penultimate glaciation-Holocene)

The lithological analysis of sediments from Core SO201-2-85KL (18 m long) taken from the Shirshov Ridge in the western part of the Bering Sea (57°30.30′ N, 170°24.79′ E, water depth 968 m), which recovered the section spanning from the penultimate glaciation till Holocene, revealed their mostly terrigenous composition with several intercalations of diatomaceous ooze. The latter was accumulated mainly during relatively warm epochs (last interglacial and Holocene) with elevated bioproductivity of surface waters. Sedimentation during the penultimate glaciation was strongly influenced by bottom currents. Ice rafting of detrital material was intensified during cold marine isotope stages (MIS 6, MIS 4, MIS 2). Glaciations were accompanied by increased sedimentation rates probably due to the glacioeustatic sea level falls, desiccation of the Bering Sea shelf, and enhanced influx of sedimentary material transported by large rivers immediately to the deepwater basin.

Effect of additional excitation in the X-ray fluorescence determination of noble metals in unsaturated beds

The relative contribution of effect of additional excitation of iridium and gold atoms appearing in unsaturated beds in using substrate from corresponding material is studied. The mathematical design of experiments is used to rank factors affecting the analytical parameters of X-ray fluorescence analysis in the determination of noble metals.

The use of statistical methods for studying the chemical composition of oceanic sediments: Evidence from deep-water Upper Pleistocene-Holocene sediments in the Gakkel ridge, part II

This paper is a continuation of the work that was published in Geochemistry International in 2010 [1]. Based on lithological and trace-element study of sediments, a hypothetical lithostratigraphic model was proposed and lithostratigraphic horizons were identified. In this paper, we carried out statistical treatment of chemical data (on 28 elements) on the Upper Pleistocene-Holocene sediments of the Gakkel Ridge (core PS 70/306-3). Cluster analysis coupled with lithostratigraphic data was used to distinguish individual groups (clusters) of the core beds, while factor analysis allowed deciphering the main stages in the sedimentation history.

Error of sample preparation in pressing emitters for X-ray fluorescence analysis

When determining element concentrations in geological samples by X-ray fluorescence spectrometry using emitters obtained by pressing tablets from powder samples, we revealed the effect of a significant difference in line intensities of characteristic long-wavelength emission (ΔIi) from opposite sides of the emitter. The effects of compacting pressure, mass of emitter, and its surface area on ΔIi were investigated. It was shown that the account of this effect can reduce the error of sample preparation in using compacting pressures lower than 20 t.

Permeable Reactive Barriers Based on Natural Zeolites from Kazakhstan in Solving Ecological Problems: Mathematical Model and Simulation

In view of ecological problems stemming from the leakage of reservoirs with liquid radioactive wastes (LRW) and groundwater contamination with radioactive Cs+ and Sr2+, we have estimated the physicochemical (including sorption) characteristics of clinoptilolite-bearing tuff (CBT) from the Chankanai deposit in Kazakhstan. Data were obtained on the chemical and phase composition of CBT, its total cationexchange capacity, and equilibrium (exchange isotherms) and kinetic (diffusion coefficients) characteristics in sorbing radioactive Cs+ and Sr2+ from 0.07 n CaCl2 solution (model solutions of groundwaters). We proved that CBT efficiently sorbs Cs from this solution and practically does not sorb Sr and elucidated the reasons for the low selectivity with respect to Sr2+. Based on the equilibrium and kinetic characteristics of the process, a mathematical model is suggested for Cs sorption under dynamic conditions. The protection lifetime of the clinoptilolite-based geochemical barrier is evaluated.