(Table 2) Abundance of the main groups of planktonic animals in the 250-900 m water layer at the Broken Spur and Lost City sites according to visual counts from the Mir manned submersibles in 2002 and 2005

Three dives of the Mir manned submersibles with plankton counts and two vertical plankton hauls with a BR net were carried out above the Lost City (Atlantis underwater massif) and the Broken Spur hydrothermal fields during cruise 50 of R/V Akademik Mstislav Keldysh. Above the Atlantis seamount no significant increase in plankton concentration was found. Above the Lost City field horizontal heterogeneity of plankton distribution in the near-bottom layer and in overlying water layers was shown. Near-bottom aggregations of euphausiids and amphipods previously reported by other scientists seem to be related to attraction of these animals by the submersible's headlights rather than represent a natural phenomenon.

(Table 2) Species composition of agglutinated foraminifers from the abyssal zone of the Pacific Ocean

The quantitative study of distribution and taxonomic composition of recent living and dead (without plasma) benthic foraminifers revealed three foraminiferal assemblages in bottom sediments of the Pacific Ocean at depths of 3350 to 4981 m. The assemblage dominated by epibenthic Lagenammina difflugiformis, Reophax dentaliniformis, and Saccorhiza ramose occupies slopes of underwater hills. The assemblage with a high share of infaunal Cribrostomoides subglobosum, C. nitidum, and Ammobaculites agglutinans is registered on an abyssal plateau. The assemblage with a significant proportion of large Astrorhiza and Reophax species, which are characterized by active way of life, populates gentle slopes and narrow depressions with potentially strong bottom currents.

Chemical composition and K-Ar age of rocks from the northern Sea of Japan

The Middle Paleozoic complex consists of terrigenous and volcanogenic materials metamorphized in greenschist facies. Clastic rocks have arkosic composition and are formed by alteration of basalts and metamorphic rocks. Metaeffusives were formed from basaltoid products of oceanic tholeiite magma indicating that underwater rise structures of the northern Sea of Japan were emplaced on the oceanic crust.

Chemical composition of celadonite-glauconite minerals and cristobalite from altered oceanic basalts of DSDP Hole 49-407

Features of associations of newly formed minerals in Oligocene basalts from the Reykjanes Ridge (DSDP Hole 407), which consist in wide development of celadonite-glauconite group minerals, as well as saponite, cristobalite and specific Fe-Si formations is shown. Detailed mineralogical and geochemical characteristics of these newly formed minerals are reported. It is firstly shown that at underwater alteration of basalts not only celadonite can be generated, but also glauconite. Dependence of secondary mineral composition from petrochemical features of original basalts and from their permeability is revealed. It is concluded that complexes of secondary minerals formed during alteration of basalts with similar petrochemical characteristics in the ocean and on the continent are different.

(Table 2) Chemical composition of bottom sediments from the Equatorial East Pacific

Fe, Mn, Cu, Ni, and Co contents in bottom sediment samples from the Clarion Clipperton fracture zone and Guatemala Basin were studied; maps of their distribution in the upper layer of sediments were prepared. At some stations contents of these elements were also measured in Pleistocene and Oligocene sediments. Elevated contents of five ore elements (except for Zn) were found at the East Pacific Rise and in the Clarion-Clipperton province; and of Mn, Ni, and Cu in the Guatemala basin. Increased zinc contents occur only in sediments of the East Pacific Rise and Guatemala Basin. Enrichment of sediments in these elements results from under¬water hydrothermal activity and high biological productivity.

Abundance and biomass of benthic foraminifera in bottom sediments from the Sea of Okhotsk and the Pacific Ocean

A study of distribution of live individuals of benthic foraminifera in sediments of the Sea of Okhotsk and of the Northwestern Basin of the Pacific Ocean shows that they can be present in sediments up to depth of 30 cm and probably can live there for long periods, sometimes forming high concentrations. Living individuals in the subsurface layer often account for more than 50% of total biomass, which varies from 1 to 21 g/m**2 in different morphological structures. The largest biomass values are attained in underwater rises embedded in relatively warm, oxygen-saturated Pacific waters. Minimum total biomass concentrations occur in deep-water depressions where stagnation phenomena are observed. Foraminifera biomass everywhere decreases gradually with increasing depth from the surface of sediments regardless of relief, depth, and nature of sediments.

(Table 4) Chemical composition of a hydrothermal body from the Red Sea rift zone

The main features of geological structures of ocean rift zones based on results of studies of the P.P. Shirshov Institute of Oceanology with use of manned submersibles "Pisces" are under consideration in the book. Multiyear experience of geological exploration in rift zones with the use of these submersibles is summarized. Methodology of underwater operations is described. The main structural features of the Red Sea and Gulf of Aden rifts as well as the rift zone of the Reykjanes Ridge are considered.

Chemical composition of Fe-Mn nodule from Station PL70-9

During June-August 1970 geologic investigations were carried out to the west of the Cape Verde Islands. One result of these investigations was a discovery of a new region of distribution of iron-manganese nodules. Data on chemical analysis of the nodules and their morphometric characteristics are presented in this paper. The report is illustrated by bottom-relief profiles, underwater photographs, and tables.

(Table 1) K-Ar age of alkaline igneous rocks from the Jan Mayen fracture zone

Bottom morphology of the Jan Mayen transform fracture zone and rock chemistry data show that petrological and chemical specific features of igneous rocks can result from higher permeability of the transform fracture zone and deeper penetration of ocean water into the lithosphere in comparison with rift zones of the Kolbeinsey and Mohn's mid-ocean ridges. Age of alkaline magmatism of the Jan Mayen fracture zone is similar to that of rift zones due to palingenesis of metamorphosed and hydrated mantle and crustal rocks.