Abundance of nodules, chemical and mineral compositions of nodules and sediments from the Central Pacific

The monograph considers facial conditions of ore-formation in the Central Equatorial Pacific, as well as lithostratigraphy and local variability of bottom sediments. Mineral composition of nodules, forms of occurrence of chemical elements in sediments and nodules, composition of interstitial waters, age of nodules, regularities and processes of ore formation in the radiolarian belt of the Pacific Ocean zone are also under consideration.

Chemical composition of bottom sediments from the Baltic Sea

According to geochemical analyses carbonaceous sediments from deep basins of the Baltic Sea containing 3-5% of organic carbon are enriched in some metals such as Cu, Mo, Ni, Pb, Zn, V, and U relative to shallow-water facies of the Bay of Finland. These metals also enrich (relative to background values in clayey rocks) ancient carbonaceous shales, where the average Cu and V contents are slightly higher and that of Mo, Pb, and Zn lower than in deep-sea carbonaceous sediments of the Baltic Sea. In addition, the deep-sea carbonaceous sediments of the Baltic Sea are enriched (but less notably than ancient shales) in Ag, As, Bi, and Cd. These data confirm previous assumptions that carbonaceous sediments accumulating now in seas and oceans can be considered as recent analogs of ancient metalliferous shales.

Chemical and amino acid compositions of bottom sediments from the Canary upwelling

Amino acid composition of bottom sediments on the northwestern continental slope of Africa is determined. Correlation similar to that found earlier in Caspian sediments between type of amino acid spectra of Atlantic sediments and distribution of reduced forms of sulfur in them is found. These correlations result from geochemical activity of benthic biocoenosis, which transforms sulfur compounds.

(Table 1) Chemical compositions of iron-manganese phosphate crusts, phosphorites, volcanic products, and phosphate limestones from ocean seamounts

New data on phosphorites of Atlantic seamounts are presented and used in combination with published data to analyze sources of phosphorus in them.

Chemical composition of bottom sediments and rocks from DSDP Holes 3-14 through 64-477

Data on analyses of chemical composition of DSDP samples of bottom sediments and rocks carried out in P.P. Shirshov Institute of Oceanology are reported. Basal sediments and sedimentary rocks prevail in the sample set.

Chemical composition of phosphorites, Fe-Mn nodules and crusts, and basalts from the West Pacific

The monograph gives the first systematic description of ore-bearing guyots from the West Pacific. It is mostly based on data obtained in numerous expeditions of Russian vessels during 1984-1992. Ore deposits located on upper parts of all slopes and tops of the guyots include phosphorites associated with cobalt- and platinum-rich ferromanganese crusts. Location, origin and prospecting of mineral deposits are discussed on the base of new data on metallogenic factors (geodynamics, tectonics, magmatism, sedimentation and morphostructures).

Microfossils and chemical elements in bottom sediments of the Ashadze-1 Hydrothermal Field (tropical Mid-Atlantic Ridge)

The first thorough analysis of microfossils from ore-bearing sediments of the Ashadze-1 Hydrothermal Field in the Mid-Atlantic Ridge sampled during Cruise 26 of R/V Professor Logachev in 2005 revealed substantial influence of hydrothermal processes on preservation of planktonic calcareous organisms as well as on preservation and composition of benthic foraminifera. From lateral and vertical distribution patterns and secondary alterations of microfossils it is inferred that the main phase of hydrothermal mineralization occurred in Holocene. Heavy metals (Cu, Co, Cr, and Ag) were accumulated by foraminiferal tests and in their enveloping Fe-Mn crusts. Distribution of authigenic minerals replacing foraminiferal tests demonstrates local zoning related to hydrothermal activity. There are three mineral-geochemical zones defined: sulfide zone, zone with elevated Mg content, and zone of Fe-Mn crusts.