(Table 2) Radiolaria species in nodule samples from the Clarion-Clipperton province, Pacific Ocean

Radiolaria were studied in 19 manganese nodules raised from the bottom. The nodules occurred mainly on the surface of thin Quaternary sediments covering Tertiary deposits of various ages (Middle Eocene to Early Miocene). Radiolaria in nodule cores and in inner and surface layers were studied. We found 85 radiolaria species and groups of species. Usually 1-4 to 6-19 radiolaria species were detected in each of the samples. Species belonging to Middle Eocene, Late Miocene to Early Oligocene, and Oligocene to Early Miocene were found. Rare Neogene species were revealed only in fractured surface layers. Age of the nodules is mainly Oligocene. Seismic waves cause sediment vibration, loosening disintegration, and removal of suspension by bottom currents. The vibration effect causes ancient nodules to float up to the surface of Quaternary sediment. This hypothesis suggests the reason for characteristics of the Clarion-Clipperton zone: regional stratigraphic hiatus, accumulation of residual fields of nodules, and the ''floating up'' of nodules to the surface of the Quaternary sediments.

(Table S2, page 46-47) Manganese nodule sampling station data

Legacy product - no abstract available

Detailed measurements of radium inside a nodule of Albatross 1899-1900 - for Stations 13, 173 and 4658

Thanks to the courtesy of the British Museum of Natural History the author obtained from their Challenger collections two small nodules, and through a similar courtesy of the Mineralogical Department of the Riksmuseum in Stockholm one half of a much larger nodule, also from the Challenger Expedition. Results from his initial measurements of the radium contents of these samples convinced the author that the radium in the nodules is accumulated from the surrounding sediment. In the present paper the author conducted a much more thorough investigation on nodules obtained during the U.S. Albatross cruises of Dr. Agassiz. Detailed measurements of radium were conducted on individual layers and spots inside each nodule.

Composition of Cape Leeuwin Manganese nodule deposit off Western Australia

In 1970 a large deposit of ferromanganese nodules was discovered on the floor of the Indian Ocean southwest of Cape Leeuwin by the research vessel USNS Eltanin. This discovery, which was based largely on bottom photographs from about 20 stations, was discussed by Frakes (1975) and Kennett and Watkins (1975, 1976). The photographs suggest that the deposit spreads, nearly continuously, over 900 000km^2, and cores showed that the nodules are essentially confined to the sediment surface. Kennett and Watkins (op. cit.) pointed to the abundance of ripple and scour marks and current-formed lineations on the present surface, and of extensive disconformities in the cores, as evidence of strong present and past bottom currents in the region. They suggested that the current action had resulted in very low sedimentation rates, which had allowed the nodule field, named by them (1976) the 'Southeast Indian Ocean Manganese Pavement', to develop. In early 1976 the authors used the research vessel HMAS Diamantina for a 10-day cruise in the region to sample the nodules in order to study their chemistry and mineralogy. During the cruise 9 stations were occupied, 8 of them successfully (Figure 1), and about 2000 nodules were recovered from the sea bed. The apparatus used was a light box dredge on the ships hydrowire, which had a breaking strain of about one tonne. Although an attempt was made to reoccupy Eltanin photographic stations, it should be noted that positioning was by celestial navigation, so errors of up to 10 km are possible.

Geochemistry of a manganese nodule from the WALDA (R/V Jean Charcot) expedition

During the 1971 WALDA expedition of the R/V Jean Charcot in the Equatorial and South Atlantic, manganese nodules were recovered at Station 24 - DS 17 at the base of the continental platform off the coast of Angola. They were analysed at the Laboratoire de Géochimie des Eaux, Université Paris VII Denis Diderot.