Search

A sediment core section nearly 230 cm long (190–420 cm below the sea bottom) from the northeastern Pacific is largely composed of smectite. X-Ray, thermal, i.r. and chemical analyses indicate the smectite to be an iron-rich montmorillonite (SiO 2 , 51·66%; TiO 2 , 0·58%; Al 2 O 3 , 8·13%; Fe 2 O 3 , 14·08%; FeO, 0·51%, MnO, 0·29%; MgO, 4·21%, CaO, 0·15%; Na 2 O, 1·21%; K 2 O, 0·71%; H 2 O + , 6·74%; H 2 O−, 10·13%; total 98·40%). The hypothesis that the Fe-smectite could have been formed by the interaction of hydrothermal solutions and seawater is by circumstantial evidence.

Microbiological examination of a sediment core from the Black Sea showed 1320 viable organisms per gram at the surface, 630 per gram 5 cm below the surface, 760 per gram at the 10-cm level, and 700 per gram at the 20-cm level, which had been laid down about 400 years ago, according to radiocarbon dating. Many of the isolates belonged to known clostridial species, although most did not. The predominant organism found below the surface was an aerotolerant Clostridium, C.durum, sp. nov.

An idealized model is proposed to illustrate the depth distribution of dissolved sulfate, in recent subaqueous sediments, that would be expected under steady state deposition. The processes considered by the model are ionic diffusion, deposition plus compaction, and bacterial sulfate reduction. Rate parameters (diffusion coefficient, rate of bacterial sulfate reduction) calculated from the model, for a sediment core from the Santa Barbara Basin of southern California, agree within an order of magnitude with values estimated by independent methods.

Cellulose acetate butyrate (CAB) core liners lose water through pores in the plastic. A wax bath has been developed to coat liners with a microcrystalline wax to retard water loss. Sealing properties of this wax are compared with those of paraffin and a combination of aluminum foil and microcrystalline wax. Over a 50-day period uncoated liners lost water at an average rate of 21·1 × 10−4 g/day/cm2 of surface area, while liners coated with microcrystalline wax or with paraffin lost less than 3·3 × 10−4 g/day/cm2. Liners coated with foil and wax did not lose water during the test.

The chemical composition of twenty-eight microscopic glassy objects, found in a deep-sea sediment core taken near the Ivory Coast, has been determined by electron microprobe analysis. Like the Australasian microtektites, these glassy objects can be divided into two main groups. One group is composed of individuals with chemical compositions similar to tektites. These are referred to as “normal” microtektites. The other group is composed of bottle-green glassy objects with low silica contents ( MgO CaO ratio (>3) and an average Na 2 O K 2 O ratio greater than unity. Although the bottlegreen objects differ from the “normal” microtektites in their appearance, physical properties and chemical compositions, they are nevertheless found in association with them and are probably therefore related to them. Both the Ivory Coast and Australasian microtektites have higher MgO and lower Na2O contents than igneous glasses with comparable SiO2 contents. The chemical data presented in this paper are interpreted as confirming a previous suggestion that the glassy objects found in deep-sea sediments near the Ivory Coast are microtektites and that they represent a portion of the Ivory Coast tektite strewn field.

A pneumatically operated core sampler is described which is easily portable and may be used by two men from a rowing boat. The apparatus takes an undisturbed sediment core 6 m long and is substantially independent of water depth up to a limit of some 250 m. The hydrostatic pressure operating on a cylindrical anchor chamber embedded in the sediment is used to hold the apparatus in contact with the bottom while the coring tube is driven downwards by compressed air. On completion of the coring operation, the anchor chamber is automatically filled with air, the coring tube is extracted from the sediment, and the apparatus brought to the water surface by the buoyancy lift. The use of heavy weights and the associated lifting tackle is therefore avoided.

An investigation was made of the diatom stratigraphy in a sediment core from Sunfish Lake, a small (8.3 ha), deep (20 m), meromictic lake in southwestern Ontario. About 340 diatom species and varieties distributed among 37 genera were identified from the sediments; however, only 16 taxa had more than 2% representation in any sample. On the whole, the number of individuals and diversity of the samples increase over the postglacial period. Diatoms first appear in pollen zone A and consist mainly of the littoral forms Cymbella diluviana, Fragilaria lapponica, and F. construens var. venter. It is suggested that these taxa are typical of early postglacial lacustrine sediments in northeastern North America. Cyclotella bodanica first appears in zone B and is dominant in most samples throughout the core. It is euplanktonic and typical of subalpine, circumneutral, oligotrophic lakes. In C2, when the climate was possibly warmer and drier than present, there is evidence for a lower lake level: C. bodanica is temporarily replaced in importance in the sediments by C. kuetzingiana and the proportion of littoral and epiphytic diatoms increases. Cyclotella bodanica regains its former importance in C3 sediments with the possible return to a cooler, wetter climate. About 850 years before present (B.P.) the lake evidently became eutrophic. Cyclotella bodanica declines and there is an increase in the proportion of several species typical of a higher trophic level, e.g., Stephanodiscus hantzschii, Cyclotella glomerata, and several Synedra spp. The cause is unknown. The lake probably became meromictic about 140 B.P. at a time when the forest was cleared and agriculture began in the watershed.

A relatively high content of manganese at the top of an arctic sediment core and a smooth exponential increment of manganese concentration in its interstitial water down to one meter have been found. The data strongly support the idea that manganese may be remobilized after burial by local reducing conditions. The thermodynamic calculation shows that the interstitial water is reaching chemical equilibrium with respect to MnCo3 precipitate in the deeper part of the sediment.

Three new taxa of diatoms, Achnanthes duthii sp. nov., Achnanthes undulatus sp. nov., and Neidium distincte-punctatum Hustedt var. major var. nov., are described from a sediment core obtained from Sunfish Lake, Waterloo County, Ontario.

Sediment core samples collected from the northeastern part of the Arabian Sea during cruise-2 on board I.N.S. ‘Darshak’ in January to February, 1967 have been analysed for study of the nature and distribution of Foraminifera. Ninety-two species of Foraminifera belonging to 40 genera of 16 families,viz., Textulariidae, Valvulinidae, Miliolidae, Ophthalmidiidae, Trochamminidae, Lagenidae, Planorbulinidae, Nonionidae, Camerinidae, Heterohelicidae, Buliminidae, Rotaliidae, Calcarinidae, Globigerinidae, Globorotaliidae and Anomalinidae have been identified and reported. Composition of Foraminifera and their concentration at different stations have been studied with reference to depth and state of preservation, benthic and planktonic Foraminifera being dealt with separately.

Over 6000 microscopic glass spherules between 125 μm and 1 mm in diameter were found in a sediment core (RC9-58) from the Caribbean Sea. These glassy objects are mostly confined to a zone ∼ 40 cm thick at a depth of ∼ 250 cm. We believe that the microscopic glass objects are microtektites belonging to the North American strewnfield, based on their geographical location, appearance, physical properties, stratigraphic age (middle Upper Eocene), fission track age (∼34.6 my) and major element compositions. The occurrence of North American microtektites in the Caribbean Sea indicates that the North American strewnfield is two to three times larger than previously indicated. An estimate on the abundance of microtektites in core RC9-58 indicates that the North American strewnfield may contain greater than 1017 g of tektite material.

Measurements have been carried out on the average radiocarbon activity of a sediment core of eupelagic chalk ooze and the age of the lower boundary was calculated by integration of the radiocarbon decay function. In such cores where constancy of the rate of minerogenous accumulation is indicated and can be checked by lateral control, the titanium content, calibrated in terms of absolute age by means of radiocarbon measurement, can be used for dating as far back in time as the constancy of the rate of minerogenous sedimentation can be proved. DOI: 10.1111/j.2153-3490.1951.tb00803.x

In a recent article Ewing, LePichon, and Ewing cite the proximity of a number of pre-Pleistocene cores to the axis of the mid-Atlantic ridge as evidence that continental rifting ceased 20 m.y.b.p. at the latest and probably did not occur at all. It is here suggested that these data do not necessarily preclude crustal spreading at a constant rate. Further, a schematic model of mantle convection is suggested which fits the sediment core data, provides for nonuniform rates of crustal spreading, while allowing steady-state mantle convection, and qualitatively explains many features observed on mid-ocean ridges.

1. Six scientists and technicians were trained in lock-out diving from the submersible “Deep Diver”. 2. A planned program of saturation diving on predetermined sites in depths between 150 and 250 feet (46 and 76 m) was only partially successful because of extreme cold experienced by divers breathing heliox mixtures in 3.5° C water, and because of inadequacies in the submarine handling system. 3. An alternate system of bounce lock-out dives permitted completion of an abbreviated scientific program in depths down to 287 ft (87.5 m). 4. Divers took photographs, rock and sediment core samples, and made collections of common benthic species for subsequent analysis for environmental contaminants. 5. It was effectively proved that diver scientists can train rapidly for lock-out diving programs and perform effective scientific work.

The only deternfinations of past cosmic-ray intensity were based on studies of cosmic-ray-produced C/sup 14/ These studies have shown that up to 10,000 to 15,000 years ago, the cosmic-ray intensity was the same within plus or minus l0%. The measurements of Kulp and Volchok on C/sup 14/ concentration in sections of ocean sediments showed the cosmic-ray intensity remained substantially constant in the last 30,000 years. These results, however, depend on the validity of ionium age determination method and have recently been criticized. Two years ago it was pointed out that the 2.7 million year half life Be/sup 10/, which is produced mainly in interactions of cosmic rays with atmospheric ritrogen nuclei, may finally accumulate in deep sea sediments and should be detectable in regions of small sedimentation rates. If such sediments can be found which buve remained undistarbed in the past, its studies should yield the cosmic-ray intensity up to 10 million years in the past. Beryllium-10 has been detected in deep Pacific sediments and its concentrations analyzed in the upper and lower ends of 14meter sediment core. The experimental procedure and results are described. The present day global deposition of Be/sup 10/ was calculated from the available cosmicray andmore » accelerator dnta and also estimated from the observed deposition rate of another cosmic-rayproduced isotope, Be/sup 7/ . The two estimates agree on the present day deposition rate of 2.3 x 10/sup 6/ Be/sup 10 nuclei cm-/sup 2/ year-1. The resnlts are therefore consistent with a constart cosmnic-ray intensity up to ~ 2 million years. (A.C.)« less

A bstract. Extrusion and fractionation are necessary steps for most sediment core analyses. We designed a new device that rapidly fractionates the core sample as it is extruded from the core tube. The fractionator works well with consolidated or fluid sediments. Results indicate that the fractionator gives representative samples with little or no vertical contamination of the core sample.

Glassy objects of spherical, oval, dumbbell, teardrop, and irregular shapes have been found in a deep-sea sediment core taken off the Ivory Coast. They occur in a layer of sediment that was apparently deposited about 800,000 years ago. Their geographic location, appearance, and physical properties suggest that they are microtektites and that they are related to the tektite-strewn field of the Ivory Coast.

Sediment samples were collected from the Liberty Island Anchorage and Military Ocean Terminal in Bayonne, New Jersey (MOTBY), during a survey conducted from June 7 through June 10, 1994. Tests and analyses were conducted on Liberty Island Anchorage sediment core samples according to the manual developed by the U.S. Army Corps of Engineers (USACE) and the U.S. Environmental Protection Agency (EPA), Evaluation of Dredged Material Proposed for Ocean Disposal (Testing Manual), and the regional manual developed by the USACE-New York District (NYD) and EPA Region 11, Guidance for Performing Tests on Dredged Material to be Disposed of in Ocean Waters. The evaluation of proposed dredged material from Liberty Island Anchorage consisted of bulk sediment chemical analyses, chemical analyses of site water and elutriate, and water-column and benthic acute toxicity tests. Individual sediment core samples collected from Liberty Island Anchorage were analyzed for grain size, moisture content, and total organic carbon (TOC). A composite sediment sample, representing the entire area proposed for dredging, was analyzed for bulk density, metals, chlorinated pesticides, polychlorinated-biphenyl (PCB) congeners, polynuclear aromatic hydrocarbons (PAH), 1,4-dichlorobenzene, and dioxin/furan congeners. Site water and elutriate water, prepared from the suspended- particulate phase (SPP) of Liberty Island Anchorage sediment, were analyzed for metals, pesticides, and PCBS.

Isoleucine has been found to undergo a slow racemization reaction in a 5-meter sediment core taken from the Atlantis fracture zone (water depth, 4014 meters; actual location, 30 degrees 15.7'N, 43 degrees 18.9'W). The amount of racemization increases with increasing depth below the sediment-seawater interface. This isoleucine racemization reaction was used to calculate an age of 1.23 million years for the bottom of the core.

A shallow water core sampler was constructed from plumbing materials and extruded plexiglas tubing. Construction of the sampler is simple and the total cost of materials is approximately $35. The sampler is capable of taking cores at water depths up to 6m and by modification at greater depths. The total weight of the sampler is 12 kg; it is easy to operate and can be used for sediments ranging in texture from sand to highly organic clayey material. Core samples varying in length and cross-sectional area can be obtained by changing the dimensions of the plexiglas tube.

The concentrations of the major fatty acids were determined for the varied layers of an algal mat community. The living mat contains substantial amounts of the unsaturated acids, while the underlying layers become progressively depleted in unsaturated molecules. A similar progressive increase in the ratio of saturated to unsaturated acids was detected in a sediment core from a hypersaline lagoon.

The suborder Cladocopa comprises 3 genera and about 41 living species, which are worldwide in distribution. Most Recent species are limited to the coastal waters of northwestern Europe and the Mediterranean Sea. Fossil occurrences are limited to Europe, with the exception of 4 specimens found near the top of a North Atlantic sediment core, Large forms from the Paleozoic of Europe are referable to the family Leperditellidae rather than to the Cladocopa. Recent Cladocopa are found exclusively in waters of normal salinity, and seem to prefer water temperatures between 4 degrees and 14 degrees C. Although collected occasionally at depths of 1280 to 2600 m., they are usually found in waters less than 500 m. deep. The geologic evidence indicates that the anterior shell concavity was a late acquisition and may be an adaptation permitting more efficient swimming. If so, this may enable the Cladocopa to complete more successfully, and thus may account for the relatively large number of Cladocopa existing at the present time. A new species of the genus Polycope from the Great Bahama Bank is described and figured. Important papers concerning Recent Cladocopa are included in the bibliography.