Age of bottom sediments and minerals from the Atlantic and Pacific oceans

Application of nuclear geochronology methods in study of recent sedimentation processes, in paleoceanology, tectonics, geomorphology, and other problems associated with accumulation of sedimentary material in oceans and seas are under consideration in the book. A comparative analysis of dating results obtained by biostratigraphy, paleomagnetic and nuclear geochronology methods is given.

Concentrations of Fe, Mn, Cu, Zn, Co, Ni, Pb, Cd, B, and SiO2 in interstitial waters from bottom sediments of the Atlantis II and Discovery Deeps, Red Sea rift zone

Chemical analyzes show that interstitial waters from ore-bearing bottom sediments of the Atlantis II and Discovery Deeps are enriched in Fe, Mn, Cu, Ni, Co, Zn, Pb, and Cd compared to sea water. Enrichment factors of these trace elements in the interstitial waters of the Atlantis II Deep relative to the sea water vary within the following ranges: for Fe from 100 to 7000, for Mn from 19047 to 32738, for Zn from 500 to 1600, for Pb from 78333 to 190000, for Cu from 107 to 654. Comparison of average weighted concentrations of Fe, Mn, Zn, Pb, Cu, Ni in the bottom sediments and the interstitial waters of the Atlantis II Deep indicates common regularities and good relationship in distribution of these elements along sediment cores. Differences in concentrations and distribution of the studied trace elements in the interstitial waters of the Atlantis II and Discovery Deeps result from different chemical compositions of hydrothermal fluids entering these deeps.

Chemical and mineral compositions of Northwest Pacific bottom sediments and their grain size fractions

A detailed study of chemical composition of bottom sediments along a profile through the Northwest Pacific Basin has allowed to identify and describe four lithofacies types of bottom sediments. Distinguished types of sediments form a genetic series reflecting changing conditions of sedimentation from near-shore to central regions of the ocean. Along the strike of pelagic clays a gradual transition from ash containing clays to zeolite containing clays is established. Ash particles and zeolites have similar forms of occurrence. Together with other data it suggests that zeolites have been formed by diagenetic transformation of rhyolitic glass. Regular changes of CaCO3, amorphous SiO2, Fe and Mn contents in bottom sediments from the coast to the pelagic zone are shown.

Grain properties of rock fragments from shelf bottom sediments of the Sea of Okhotsk

Grain size, shape and roundness of rock fragments, texture, composition of bottom sediments from the Sea of Okhotsk are under study. These data are compared with parameters of modern lithodynamic conditions of the sea and genetic types of deposits are identified. These criteria are used for partition of Holocene and Upper Pleistocene sediment series and for identifying conditions of their formation. Dependence of structure of different genetic types of deposits on intensity of hydrodynamic processes, of terrigenous contribution, and on direction consedimentational tectonic movements is under consideration.

Phosphorus in bottom sediments and micronodules from Core VITYAZ7414, Central Indian Ocean

Study of phosphorus distribution in grain size fractions of eupelagic clays showed high (up to 3%) content of P in Fe-Mn micronodules that can contain up to 20-30% of total P. Mineral P associated with Fe in ocean sediments is an analog of manganese in ocean sedimentogenesis. Sharp decrease of P contents in ocean Fe-Mn nodules compared to ones from seas results from decrease of Fe contents and partial neutralization of Fe activity by Mn.

Radiocarbon datings of Upper Quaternary bottom sediments from the Mediterranean Sea

Bottom sediment samples were collected in the Central Mediterranean, Southern Adriatic, Tyrrhenian, Algerian-Provencal, and Alboran basins of the Mediterranean Sea. Fifty-six datings were done for 12 sediment cores. The lowest sedimentation rates during Holocene were found on the abyssal plain of the Algerian-Provencal basin (2.4-4.0 cm/ky). In the Southern Adriatic, Tyrrhenian, and Alboran basins sedimentation rates were somewhat higher (6-12 cm/ky). On slopes of the Southern Adriatic and Tyrrhenian basins during Late Würm glaciation rates of "normal" sedimentation were within the range 11.8-26.8 cm/ky.