ALBERT

Description: Because of its position between the North Atlantic and the Arctic oceans, its young age, small size, and diversity of geological structures, the Norwegian-Greenland Sea provided a unique target for deep drilling on Leg 38 of the Glomar Challenger. From studies of the sediments and basement rocks it was expected to gain insight particularly as to the following: 1) The tectonic framework and evolution of this area with special emphasis on the continental margins and on questions concerned with shifts of spreading axis and existence of foundered continental areas. 2) The youngest times of existence of land bridges between Eurasia and North America and the effect these land bridges had on water circulation and paleoclimates. 3) The date of the initiation of glaciation and dates of glacial advances and retreats. 4) Description of the Tertiary marine microfauna and microflora of the Norwegian-Greenland Sea, which are essentially unknown at present, and investigation of their similarity with microfauna and microflora from other areas.

Description: Twenty-four manganese nodules from the surface of the sea floor and fifteen buried nodules were studied. With three exceptions, the nodules were collected from the area covered by Valdivia Cruise VA 04 some 1200 nautical miles southeast of Hawaii. Age determinations were made using the ionium method. In order to get a true reproduction of the activity distribution in the nodules, they were cut in half and placed for one month on nuclear emulsion plates to determine the alpha-activity of the ionium and its daughter products. Special methods of counting the alpha-tracks resolution to depth intervals of 0.125 mm. For the first time it was possible to resolve zones of rapid growth (impulse growth) with growth rates, s 〉 50 mm/106 yr and interruptions in growth. With few exceptions the average rate of growth of all nodules was surprisingly uniform at 4-9 mm/10 yr. No growth could be recognized radioactively in the buried nodules. One exceptional nodule has had recent impulse growth and, in the material formed, the ionium is not yet in equilibrium with its daughter products. Individual layers in one nodule from the Indian Ocean could be dated and an average time interval of t = 2600±400 yr was necessary to form one layer. The alternation between iron and manganese-rich parts of the nodules was made visible by colour differences resulting from special treatment of cut surfaces with HCl vapour. The zones of slow growth of one nodule are relatively enriched in iron. Earlier attempts to find paleomagnetic reversals in manganese nodules have been continued. Despite considerable improvement in areal resolution, reversals were not detected in the nodules studied. Comparisons of the surface structure, microstructure in section and the radiometric dating show that there are erosion surfaces and growth surfaces on the outer surfaces of the manganese nodules. The formation of cracks in the nodules was studied in particular. The model of age-dependent nodule shrinkage and cracking surprisingly indicates that the nodules break after exceeding a certain age and/or size. Consequently, the breaking apart of manganese nodules is a continuous process not of catastrophic or discontinuous origin. The microstructure of the nodules exhibits differences in the mechanism of accretion and accretion rate of material, shortly referred to as accretion form. Thus non-directional growth inside the nodules as well as a directional growth may be observed. Those nodules with large accretion forms have grown faster than smaller ones. Consequently, parallel layers indicate slow growth. The upper surfaces of the nodules, protruding into the bottom water appear to be more prone to growth disturbances than the lower surfaces, immersed in the sediment. Features of some nodules show, that as they develop, they neither turned nor rolled. Yet unknown is the mechanism that keeps the nodules at the surface during continuous sedimentation. All in all, the nodules remain the objects of their own distinctive problems. The hope of using them as a kind of history book still seems to be very remote.

Description: The major purpose of Leg 31 was the scrutiny of tectonic, sedimentologic, volcanic, paleontologic, and paleooceanographic processes operative in arc-marginal basin complexes along with a deciphering of basin history. The 12 sites ultimately occupied during Leg 31 all yielded significant new data bearing on the nature and evolution of the West Philippine Basin, Shikoku Basin, and Sea of Japan. The major objective at sites 290 through 292 was to test the mode and age of origin of the West Philippine Sea with emphasis on the nature of the Central Basin Fault. Sites 294/295 were drilled far to the east of the Central Basin Fault zone in the thin sediment blanket covering deeper portions of the northeastern West Philippine Basin. The other sites were situated in the Sea of Japan.

Description: The sites drilled on Leg 35 were selected to study the tectonic relationships and interactions between the Antarctic plate and the Antarctic Peninsula, the Scotia Arc, the southern Andes, and the Chile Ridge. Site 322 was drilled on the eastern end of the Bellingshausen Abyssal Plain where it is bounded by the Hero Fracture Zone to the northeast and the continental rise of Antarctica to the south. Site 323 was centrally located on the abyssal plain, about 30 miles west of the Eltanin Fracture Zone and about 150 miles north of the Antarctic continental rise. Site 324 was located on the gently sloping lower continental rise of Antarctica about 160 miles north of Thurston Island, the closest exposed land.

Description: he forty-first cruise of Glomar Challenger was devoted to the study of the evolution of the eastern basins of the North Atlantic, off the continental margin of West Africa. As the available data a the time was showing that most litho-stratigraphic units in the deep basins of the Atlantic had enough lateral extension, the drilling of a limited number of sites in key areas would allow for large-scale regional interpretation. One of the sites was loacted in the Cape Verde deep Basin (Site 367) while others were located in shallower waters such as, the Sierra Leone Rise (Site 366), the Cape Verde Rise (Site 368) or the Continental Slope off Spanish Sahara (Site 369).

Description: The western part of the North Atlantic Ocean holds clues to some of the most intriguing questions in marine geology. But because the geologic problems are many and varied, the sites of Leg 44 were multipurpose in nature. In particular, some of the targets were : 1) the Blake Nose, a spur of the Blake Plateau, to determine the nature, age, and origin of reef-like structures recognized on seismic profiles and 2) the Blake Outer Ridge, a long low ridge of sediments that forms the eastern boundary of the Blake-Bahama Basin, where we hoped to study the stratigraphy and sample supposed clathrates.

Description: The 286 site is located in the gap between the North and South New Hebrides trenches near the foot of the slope down from Malekula (100 km west of the island) and 370 km north of Mare in the Loyalty Island. The main objectives at the site were: 1) To determine when detritus was first shed into this basin from Malekula and thereby determine when the trench was destroyed and whether the island has moved into its present position in relatively recent time. 2) To determine the time of generation of the sea floor and compare it with that of the South Fiji Basin The Ontong-Java Plateau is underlain by a region of unusual oceanic crust that has an estimated maximum thickness of 40 km. Site 288 was located on the eastern flank of the plateau with the hope that the nature of the basement of the plateau could be determined.

Description: Two Pacific Ocean manganese nodules, one from the ocean basin and one from a sea-mount, were examined in transmission electron microscopes at 100 and 650 kV. Of the many specimens examined, ten electron diffraction crystal spot patterns were identified. Sodium birnessite was observed six times and todorokite, Giavanoli's synthetic birnessite, hydrohausmanite and -Fe2O3 one time each. Ferric hydroxide was synthesized in the laboratory and shown to be the same as the primary iron mineral observed in the manganese nodules. The ferric hydroxide had a particle size range from 30 to around 450. Manganese oxide particles were frequently embedded in a mass of smaller ferric hydroxide particles.

Description: The cores and dredges described at this site were taken on the SESAM cruise from 30 April until 10 June 1976 by the Muséum National d'Histoire Naturelle from the R/V Marion Dufresne. A total of 55 cores, dredges and camera stations were recovered and are available at MNHN for sampling and study.

Description: In 1972, the Sea Scope Expedition was commissioned by Hughes Tool Company and carried out by Global Marine Development, Inc. The object was to gather detailed information on manganese nodules, including distribution, metallic content, methods of recovery, and sea floor bathymetry in noduliferous areas. Five of six planned cruise legs were successful. The resulting report is divided into three sections.