(Table 1) Redox potential and chemical element contents in CaCO3 and amorphous silica free matter in surface layer bottom sediments of the Pacific Ocean from Hawaiian Islands to Mexico coast

Distribution of Fe, Mn, P, Ti, Cu, Ni, Co, V, Cr, W, Mo, and As in the surface sediment layer on the section from the Hawaiian Islands to the coast of Mexico (Mexico section) is studied. Contents of all studied elements increase from biogenic-terrigenous sediments off the coast of Mexico to pelagic red clays of the Northeast Basin, and more sharply for mobile elements - Mn, Mo, Cu, Ni, Co, and As. In near Hawaii sediments rich in coarsely fragmented volcanic-terrigenous and pyroclastic material of basaltic composition with high contents of Ti, Fe, V, Cr, W, and P, contents of these elements increase sharply, and contents of Mn, Mo, Ni, Co, and Cu for the same reason decrease sharply in comparison with red clay. Abnormally high contents of Mn, Mo, Cu, Ni, Co, and As in the upper layer of hemipelagic and transition sediments of the Mexico section result from diagenetic redistribution and their accumulation on the surface. Processes of diagenetic redistribution in hemipelagic and transition sediment mass of the Mexico section are more rapid than in similar sediments of the Japan section due lower sedimentation rates and higher initial concentrations of Mn. Basic similarity of element distribution regularities in sediments of Japan and Mexico sections is shown.

Composition of recent pelagic sediments from the South Pacific

Lithologic, grain size, chemical and mineral compositions of recent bottom sediments from the South Pacific are reported in the paper.

Paleoelevations in the Pacific Ocean 35 million years ago

Data from deep sea drilling, linear magnetic anomalies and bathymetric measurements together with age and morphometric characteristics of seamounts have been used to construct a paleobathymetric map of the oceans 35 million years ago. A brief analysis of these results is presented.

Changes in dynamic viscosity of sea water with depth in the Pacific Ocean at Stations DM9-613W and DM9-618W

To check on the assumption that metabolic products of planktonic organisms can affect the coefficient of dynamic viscosity of seawater, viscosity was measured in water samples taken from depths of 0 to 1843 m, west of the Hawaiian Islands. Obtained results showed that plankton has no effect on viscosity of water in regions of low productivity and that viscosity can be determined with high degree of accuracy from the appropriate tables.

Abundance of diatom cells in sediments from the Okhotsk and Bering Seas and the Northwest Pacific Ocean

The present investigation was targeted at diatom composition studies in the surface sediments (0-1 cm) sampled in the Sea of Okhotsk and the northwest Pacific in the depth range from 130 to 6110 m. The taxonomic analysis, as well as the quantitative (the diatom cell abundance per sediment dry weight unit) content and ecological group definition, was applied. Ten diatom taxa are the main body (80-100%) of the diatom assemblages: Bacterosira bathyomphala, Chaetoceros spp. (spores), Actinocyclus curvatulus, Thalassiosira latimarginata (group), T. antarctica (spores), Neodenticula seminae, Rhizosolenia hebetata f. hiemalis, Thalassiothrix longissima, Coscinodiscus marginatus, Coscinodiscus oculus iridis. The relative content of these species reflects the sedimentation conditions for different parts of the sea: the shelf, the continental slope, the open sea, and the ocean. The highest diatom content (45.6.3-60.0 mln per g of dry weight) was found for the surface sediments in the central part of the Sea of Okhotsk and the continental slope of western Kamchatka.

Mineral and chemical compositions of clay sediments from the Pacific Ocean, DSDP data

Mineral and chemical compositions, as well as conditions of formation of clay sediments in major structural elements of the Pacific Ocean floor with different ages are under consideration in the monograph. Depending on evolution of the region two ways of clay sediment formation are identified: terrigenous and authigenic. It is shown that terrigenous clay sediments predominate in marginal parts of the Pacific Ocean. Authigenic mineral formation occurring in the basal part of the sedimentary cover primarily results from removal of material from underlying basalts. This material is released during secondary alteration of the basalts due to their interaction with sea water, as well as with deep solutions.

Benthic foraminifera stable isotope data from the South Pacific sediment cores PS75/059-2 and PS75/056-1

Investigating the inter-basin deep water exchange between the Pacific and Atlantic Oceans over glacial-interglacial climate cycles is important for understanding circum-Antarctic Southern Ocean circulation changes and their impact on the global Meridional Overturning Circulation. We use benthic foraminiferal d13C records from the southern East Pacific Rise to characterize the d13C composition of Circumpolar Deep Water in the South Pacific, prior to its transit through the Drake Passage into the South Atlantic. A comparison with published South Atlantic deep water records from the northern Cape Basin suggests a continuous water mass exchange throughout the past 500 ka. Almost identical glacial-interglacial d13C variations imply a common deep water evolution in both basins suggesting persistent Circumpolar Deep Water exchange and homogenization. By contrast, deeper abyssal waters occupying the more southern Cape Basin and the southernmost South Atlantic have lower d13C values during most, but not all, stadial periods. We conclude that these values represent the influence of a more southern water mass, perhaps AABW. During many interglacials and some glacial periods, the gradient between Circumpolar Deep Water and the deeper southern Cape Basin bottom water disappears suggesting either no presence of AABW or indistinguishable d13C values of both water masses.

Sulfur compounds in bottom sediments and interstitial waters of the Pacific Ocean to the east of Japan

In near-shore Pacific bottom sediments to the east of Japan unusually high content of free H2S ocurs. H2S resulting from bacterial reduction of sulfates from interstitial waters has a number of derivatives; pyrite dominates among them. Contents of other derivatives of H2S: sulfide sulfur and organic sulfur do not exceed 0,01%, content of organic sulfur does not exceed 0.1%. Due to reduction content of sulfates can reduce to 0,03% S. Capacity of the process of sulfate reduction, estimated by sum of all reduced forms of S - derivatives of H2S, is a function of organic matter content in sediments. Ability of bottom sediments to accumulate free H2S depends on content of reactive forms of Fe. Spatial distribution of reduced forms of S in the studied sediments is considered.

Abundance and composition of Fe-Mn nodules and host sediments in the Pacific Ocean

Data on internal structure, distribution, and chemical composition of iron-manganese nodules from the central part of the South Pacific are reported. Nodules with relatively high contents of Fe, Ti, Co, and Pb were found. Formation of these nodules in pelagic regions of the ocean with low sedimentation rates is tentatively ascribed by the authors to leaching of Fe, Mn, and some minor elements during submarine lava outflow and to geochemical mobility of these elements. The role of diagenetic re-distribution of ore elements during formation of nodules is also discussed.