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| Amosse, J; Le Suave, R. |
| Pt, Pd, Rh, Ru and Au contents were determined in 35 samples of hydrogenous ferromanganese crusts and nodules from the Tuamotu Plateau (French Polynesia), collected during the Nodco II cruise undertaken by IFREMER during March 1987. These samples are characterized by high Pt and Rh contents. A statistical analysis including PGE and data on Mn, Fe, Ni, Co and Cu contents does not reveal significant correlations between the elements. Although meteoritical origin of PGE remains possible, the process of fractionation and deposition is probably hydrogenetic as confirmed by normalization diagrams to chondrite C1. This point of view is supported by the determination of some partition coefficients of PGE between the oxidized phase and the aqueous medium. The... |
| Tipo: Text |
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| Ano: 1990 |
URL: http://archimer.ifremer.fr/doc/00268/37911/35992.pdf |
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| Le Suave, R; Hoffert, M; Pautot, G. |
| During the world tour of R/V Jean Charcot , 2 types of polymetalic deposits have been investigated: the cobalt-rich crusts in the Tuamotu Archipelago (French Polynesia) and the manganese nodules in the Clarion-Clipperton Fracture Zone. In the South Pacific Ocean, a genetic model of site bearing cobalt-rich crusts has been identified: the polymetallic deposits are located at a 1,000 m water depth on a subsident fossil atoll built on a volcanic substrate. In the North Pacific Ocean, a 2 months cruise has been conducted on the basis of preexisting data (seabeam, bottom photographs, nodules and sediment sampling). Three types of geological environment have been characterized: a sedimentary plateau, an area particularly representative of the abyssals hills... |
| Tipo: Text |
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| Ano: 1990 |
URL: http://archimer.ifremer.fr/doc/00268/37941/36022.pdf |
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| Le Suave, R. |
| The Taumotou Archipelago, is considered as a potential area for the occurrence of cobalt rich ferromanganese crusts. A detailed seismic and seabeam survey carried out on the northern extension of the plateau has identified topographic highs along 2 main structural directions N 80E and N 150E. In this area, two sites have been surveyed with seabeam, 3.5 kc, and SAR side looking sonar; in addition, dredging and bottom photographs survey have been performed. For all the polymetallic crusts sampled dredged between 1,600 and 600 m, we confirm the enrichment in cobalt as a depth function; the increase in cobalt content is maximum at the outer part of the samples. |
| Tipo: Text |
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| Ano: 1990 |
URL: http://archimer.ifremer.fr/doc/00268/37952/36033.pdf |
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| Le Suave, R. |
| Three areas located in the Clarion Clipperton Fracture Zone have been identified as representative of the abyssal hills province. One of them, characterized by two mid-plate seamounts, has been more particularly surveyed during cruise NIXO 47 with the high resolution side looking sonar SAR equipped with a 3.5 kC. The main scientific results obtained during cruise NIXO 47 are relevant to the structure of deep basins, the seismic stratigraphy and the distribution of echo facies. Gravity mass movements have been identified in the old sedimentary series (before Upper Miocene) as well as at the present time. |
| Tipo: Text |
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| Ano: 1990 |
URL: http://archimer.ifremer.fr/doc/00268/37900/35981.pdf |
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