Nutrition of species of the genus Amphiophiura in the Pacific and Indian Oceans

Nutrition of 6 deep-sea ophiuroid species of the genus Amphiophiura in the Pacific and Indian Oceans has been studied. One species is a detritus-feeder while the others are carnivorous. All 6 are widespread in deep-sea eutrophic regions of both oceans. Carnivorous species are also necrophagous, feeding on dead fish, surface pteropods, and crustaceans. Fishes are consumed mainly in the Indian Ocean, pteropods in the Pacific. Thus, as shown by carnivorous Amphtophiura, the rain of dead surface pelagic organisms is one of the most important sources of food for a number of deep-sea bottom-dwelling invertebrates.

Composition of suspended matter and bottom sediments from the Atlantic Ocean and its seas

The book summarizes data on distribution and composition of sedimentary material suspended in waters of the Atlantic Ocean and its seas. Results of observations of Soviet and foreign expeditions are given. Distribution of suspended matter in sections across the ocean, as well as in the most studied seas are shown. New data on grain size, mineral and chemical composition of suspended matter are published. Summary of history of investigation of bottom sediments from the Atlantic Ocean from the first scientific cruises to the present is done. A brief description of sediment types in the ocean and a detailed description of Mediterranean Sea sediments are given.

(Table 7) Composition of rainwater collected over the Pacific and Indian Oceans in 1955-1960

Devoted to chemical interaction between the ocean and the atmosphere in the Pacific and Indian Oceans measured in 1955-1960.

Sea surface fugacity of carbon dioxide measurements in the Indian and Southern Oceans obtained during MINERVE-29/ANTARES-II cruise

The sub-Antarctic zone (SAZ) lies between the subtropical convergence (STC) and the sub-Antarctic front (SAF), and is considered one of the strongest oceanic sinks of atmospheric CO2. The strong sink results from high winds and seasonally low sea surface fugacities of CO2 (fCO2), relative to atmospheric fCO2. The region of the SAZ, and immediately south, is also subject to mode and intermediate water formation, yielding a penetration of anthropogenic CO2 below the mixed layer. A detailed analysis of continuous measurements made during the same season and year, February - March 1993, shows a coherent pattern of fCO2 distributions at the eastern (WOCE/SR3 at about 145°E) and western edges (WOCE/I6 at 30°E) of the Indian sector of the Southern Ocean. A strong CO2 sink develops in the Austral summer (delta fCO2 < - 50 µatm) in both the eastern (110°-150°E) and western regions (20°-90°E). The strong CO2 sink in summer is due to the formation of a shallow seasonal mixed-layer (about 100 m). The CO2 drawdown in the surface water is consistent with biologically mediated drawdown of carbon over summer. In austral winter, surface fCO2 is close to equilibrium with the atmosphere (delta fCO2 ± 5 µatm), and the net CO2 exchange is small compared to summer. The near-equilibrium values in winter are associated with the formation of deep winter mixed-layers (up to 700 m). For years 1992-95, the annual CO2 uptake for the Indian Ocean sector of the sub Antarctic Zone (40°-50°S, 20°-150°E) is estimated to be about 0.4 GtC/yr. Extrapolating this estimate to the entire sub-Antarctic zone suggests the uptake in the circumpolar SAZ is approaching 1 GtC/yr.

(Table 1) Positions of the Mesocena elliptica zone in sediment cores from the Pacific and Indian Oceans

The Mesocena elliptica Ehr. zone in deep-sea sediments of the Pacific Ocean is characterized by a short vertical range at the base of the Pleistocene section. Depending on sedimentation rate this zone lies at various depths below the ocean bottom. M. elliptica is unknown in recent oceanic plankton. In fossil state known species indicate that sediments containing them are of Oligocene-Miocene age. New data obtained in early 1960's show that within a short interval, evidently in Early Pleistocene, M. elliptica was abundant in plankton, primarily in tropical regions. Correlation of paleomagnetic data with results of diatom analysis shows that the Mesocena elliptica zone always lies above the Pliocene-Pleistocene boundary, and that maximum contents of M. elliptica coincide with the Jaramillo event (0.85-0.95 million years ago).

(Table 1) Positions of the Mesocena elliptica zone in sediment cores from the Pacific and Indian Oceans

The Mesocena elliptica Ehr. zone in deep-sea sediments of the Pacific Ocean is characterized by a short vertical range at the base of the Pleistocene section. Depending on sedimentation rate this zone lies at various depths below the ocean bottom. M. elliptica is unknown in recent oceanic plankton. In fossil state known species indicate that sediments containing them are of Oligocene-Miocene age. New data obtained in early 1960's show that within a short interval, evidently in Early Pleistocene, M. elliptica was abundant in plankton, primarily in tropical regions. Correlation of paleomagnetic data with results of diatom analysis shows that the Mesocena elliptica zone always lies above the Pliocene-Pleistocene boundary, and that maximum contents of M. elliptica coincide with the Jaramillo event (0.85-0.95 million years ago).

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.

Calculated sea level records and deep ocean temperatures from DSDP and ODP sites

During the mid-Pleistocene transition the dominant 41 ka periodicity of glacial cycles transitioned to a quasi-100 ka periodicity for reasons not yet known. This study investigates the potential role of deep ocean hydrography by examining oxygen isotope ratios in benthic foraminifera. Oxygen isotope records from the Atlantic, Pacific and Indian Ocean basins are separated into their ice volume and local temperature/hydrography components using a piece-wise linear transfer function and a temperature calibration. Although our method has certain limitations, the deep ocean hydrography reconstructions show that glacial deep ocean temperatures approached freezing point as the mid-Pleistocene transition progressed. Further analysis suggests that water mass reorganisation could have been responsible for these temperature changes, leading to such stable conditions in the deep ocean that some obliquity cycles were skipped until precessional forcing triggered deglaciation, creating the apparent quasi-100 ka pattern. This study supports previous work that suggests multiples of obliquity cycles dominate the quasi-100 ka glacial cycles with precession components driving deglaciations.

Sedimentation rates and geochemistry of the Atlantic and Indic Ocean of Late Miocene - Early Pliocene

Studies of the late Miocene-early Pliocene biogenic bloom typically have focused on high-productivity areas in the Indian and Pacific Oceans in order to achieve high resolution samples. Thus there is a paucity of information concerning whether the Atlantic Ocean, in general or low-productivity regions in all three basins experienced this bloom. This study measured the phosphorus mass accumulation rate (PMAR). in five cores from low-productivity regions of the Atlantic and Indian Oceans. All cores exhibit a peak in productivity 4-5.5 Ma, coincident with the Indo-Pacific bloom. This suggests that nutrients were not shifted away from low-productivity regions nor out of the Atlantic Ocean. Instead, it appears that the bloom was caused by an overall increase in nutrient flux into the world oceans. Four of the cores record the bloom's PMAR peak as bimodal, indicating a pulsed increase in phosphorus to the oceans. This suggests that there may have been multiple causes of the biogenic bloom.

Chemical composition of sepiolites and palygorskites from bottom sediments of the Eastern Indian

In fault zones of the East Indian Ridge and adjacent areas of ocean floor almost monomineral sepiolite- and palygorskite clays have been found. They have been studied by a complex of optical and physical methods. Formation of authigenic sepiolites and palygorskite had occurred under influence of Mg- and Si-rich hydrothermal solutions by metasomatic replacement of montmorillonite clays, or by precipitation from saturated solutions in cracks of various rocks.