ALBERT

Description: Sediments from near the basement of a number of Deep Sea Drilling Project (DSDP) sites, from the Bauer Deep, and from the East Pacific Rise have unusually high transition metal-to-aluminum ratios. Similarities in the chemical, isotopic, and mineralogical compositions of these deposits point to a common origin. All the sediments studied have rare-earth-element (REE) patterns strongly resembling the pattern of sea water, implying either that the REE's were coprecipitated with ferromanganese hydroxyoxides (hydroxyoxides denote a mixture of unspecified hydrated oxides and hydroxides), or that they are incorporated in small concentrations of phosphatic fish debris found in all samples. Oxygen isotopic data indicate that the metalliferous sediments are in isotopic equilibrium with sea water and are composed of varying mixtures of two end-member phases with different oxygen isotopic compositions: an iron-manganese hydroxyoxide and an iron-rich montmorillonite. A low-temperature origin for the sediments is supported by mineralogical analyses by x-ray diffraction which show that goethite, iron-rich montmorillonite, and various manganese hydroxyoxides are the dominant phases present. Sr87/Sr86 ratios for the DSDP sediments are indistinguishable from the Sr87/Sr86 ratio in modern sea water. Since these sediments were formed 30 to 90 m.y. ago, when sea water had a lower Sr87/Sr86 value, the strontium in the poorly crystalline hydroxyoxides must be exchanging with interstitial water in open contact with sea water. In contrast, uranium isotopic data indicate that the metalliferous sediments have formed a closed system for this element. The sulfur isotopic compositions suggest that sea-water sulfur dominates these sediments with little or no contribution of magmatic or bacteriologically reduced sulfur. In contrast, ratios of lead isotopes in the metalliferous deposits resemble values for oceanic tholeiite basalt, but are quite different from ratios found in authigenic marine manganese nodules. Thus, lead in the metalliferous sediments appears to be of magmatic origin. The combined mineralogical, isotopic, and chemical data for these sediments suggest that they formed from hydrothermal solutions generated by the interaction of sea water with newly formed basalt crust at mid-ocean ridges. The crystallization of solid phases took place at low temperatures and was strongly influenced by sea water, which was the source for some of the elements found in the sediments.

Description: The usefulness of cosmogenic beryllium-10 (half life = 2.5 Ma) for studying the rates of accumulation of ferromanganese nodules is reported based on its measured depth distribution in the top 20 mm of these deposits. Accumulation rates have been obtained in the range of 1 to 4 mm/Ma, which are in good agreement with rates determined using the 230Th method on the same nodules. The use of 10Be offers promise in extending the dating to the outer few cm of the nodules. This contrasts with conventional methods using 230Th and 231Pa isotopes which, due to their comparatively short half lives, are limited to a few mm at the surface of the nodules. Detailed studies of 10Be in the manganese deposits coupled with other trace element analyses should prove valuable in understanding the processes of formation of these deposits and the chronology of events recorded by them.

Description: Cruise MN-74-01 of the R/V Moana Wave was the first part of the field work of the NSF-IDOE Inter-University Ferromanganese Research Program in 1974. This program was designed to investigate the origin, growth, and distribution of copper/nickel-rich manganese nodules in the Pacific Ocean. The field effort was designed to satisfy sample requirements of the 15 principal investigators, while increasing general knowledge of the copper/nickel-rich nodule deposits of the equatorial Pacific. This report is the first of a series of cruise reports designed to assist sample requests for documented nodules, sediment, and water samples so the laboratory results can be realistically compared and related to the environment of nodule growth.

Description: Site 32 was proposed by the Pacific Advisory Panel at a location over a strong positive magnetic anomaly (Number 13 on the Pittman-Heirtzler scale, 38 million years) where samples of the basement and the basal sediment would be of value in testing hypotheses for origin of the linear magnetic anomalies from this part of the Pacific. Comparison of this site, south of the Pioneer Fracture Zone, with later sites north of the Fracture Zone would be the basis for evaluating the discontinuity formed by the Pioneer.

Description: Site 41 marks the transition from the North Pacific gyral to the Equatorial Current System. The JOIDES Pacific Advisory Panel selected a site at this latitude along the longitudinal profile of 140°W in order to obtain information on the history of migrations of these current systems.

Description: Site 40 was located by the JOIDES Pacific Advisory Panel in the region between the Molokai and Clarion Fracture Zones with the objective of recovering a continuous sediment core for the paleontologic and biostratigraphic study of the variation in sediment components at the transition between the North Pacific gyral and the Equatorial Current System.

Description: The observations described in this report were made during the NAGA Expedition, Phase 1 between San Diego and Honolulu in June 1959 by Scripps Institution of Oceanography from, the R/V Stanger. Cores, bottom photographs and dredges are available at Scripps for sampling and study.

Description: The cores described in this report were taken on the BENTHIFACE Expedition in June 1973 to July 1973 by the Scripps Institution of Oceanography from the R/V Melville. A total of 128 cores and dredges were recovered and are available at Scripps for sampling and study.

Description: This paper, explores the possibility of using manganese nodules for studying the rates of authigenic removal of trace elements to the ocean floor, i.e. considering only trace elements in hydrogenous phases (Goldberg, 1964) in sediments. It follows the then recent detailed investigations of physiochcmical properties of manganese nodules made by others. In view of the various arguments the developed regarding a slow and possibly entirely authigcnic growth of manganese nodules, the authors were led to the measurements of a host of trace elements in several already radiomctrically dated manganese nodules and sediments.

Description: Uranium concentrations in a large number of marine sediment samples of different types with world-wide spatial distribution have been determined using the rapid, precise and nondestructive technique of counting the delayed neutrons emitted during U235 fission induced with thermal neutrons. Several interesting relationships were apparent. 1) A direct proportionality was observed between percentage of organic carbon and uranium in sediments deposited in an anoxic environment in the Pettaquamscutt River in Rhode Island with concentrations ranging from 7 per cent organic carbon and 7 ppm uranium to 14 per cent organic carbon and 30 ppm uranium. A similar relationship was found in cores of sediments deposited on the Sigsbee Knolls in the Gulf of Mexico. 2) For manganese nodules a direct relationship can be seen between uranium and calcium concentrations and both decrease with increasing depth of deposition. For nodules from 4500 m in the Pacific, concentrations are 3 ppm uranium and 0.3 per cent calcium compared with 14 ppm uranium and 1.5 per cent calcium at 1000 m. 3) Relatively high uranium concentrations were observed in carbonates deposited in the deepest parts of the Gulf of Mexico, with the >88 ? carbonate fraction in Sigsbee Knoll cores having as much as 1.20 ppm. A model to explain the observed variations must include uranium enrichment in near shore environments via an anoxic pathway, followed by redeposition in a deep ocean environment with dilution either by low-uranium-bearing foraminiferal or silicious oozes or, along the continental margins, dilution with high-uranium-bearing carbonate sands.