|
|
|
|
|
| Natland, James H.; Rosendhal, Bruce; Hekinian, Roger; Dmitriev, Yuri; Fodor, Ronald V.; Goll, Robert M.; Hoffert, Michel; Humphris, Susan E.; Mattey, David P.; Peterson, Nikolai; Roggenthen, William; Schrader, Edward L.; Srivasiava, Ramesh K.; Warren, Nick. |
| The Galapagos mounds sea-floor hydrothermal system is at least 300,000 years old and once produced manganese-poor sediments, which nearly blanketed the area of the present mounds field. Present-day mound deposits are limited manganese-rich exposures, suggesting that the system has changed from rock- to water-dominated and has diminished in intensity with time. [NOT CONTROLLED OCR] |
| Tipo: Text |
Palavras-chave: Histoire Ifremer. |
| Ano: 1979 |
URL: http://archimer.ifremer.fr/doc/1979/publication-5382.pdf |
| |
|
|
| Melguen, Marthe; Debrabant, Pierre; Chamley, Hervé; Maillot, Henry; Hoffert, Michel; Courtois, Chantal. |
| The sediments of six cores from the Rio Grande Rise side of the Vema Channel reflect major phases in the sedimentary history of this area since Ihe lower Miocene. Cores taken from below the present-day lysocline (approx. 4 000 m) consist essentially of calcareous oozes. The variable degree of preservation of the Foraminifera and Coccoliths in these cores indicates dissolution cycles apparently linked to Antarctic Bottom Water (A.A.B.W.) fluctuations. Cores taken below 4 000 m represent an incomplete and shortened sedimentary sequence parliculary characterized by the presence of red Clay and manganese nodules. The latter have a todorokite core and are associated with relatively indurated phillipsite-rich sediments. In one of the deeper cores an increase,... |
| Tipo: Text |
Palavras-chave: Histoire Ifremer. |
| Ano: 1978 |
URL: http://archimer.ifremer.fr/doc/1978/publication-5228.pdf |
| |
|
| |
|
|
| Hoffert, Michel; Karpoff, Anne-marie; Clauer, Norbert; Schaaf, André; Courtois, Chantal; Pautot, Guy. |
| A sedimentological, biostratigraphical, mineralogical, geochemical (major and trace elements including rare earths) and isotopic (Rb/Sr) study was made of core samples drilled between the Touamotou Archipelago and the Marquises Islands. This structurally complex region of the South Pacific is characterised by volcanism and deep ocean water circulation. The samples consisted of two 20 cm cores of surface sediment, and a flattened nodule with indurated centre, taken close to the cores. One core sample (T KR 07) is entirely composed of brown, soft sediment. The top part of the second core (T KS 19) is also brown mud but the bottom is indurated. The brown sediment is essentially composed of phillipsite, palagonite. micronodules and nontronite. The indurated... |
| Tipo: Text |
|
| Ano: 1978 |
URL: http://archimer.ifremer.fr/doc/1978/publication-5231.pdf |
| |
|
|
| Hoffert, Michel; Karpoff, Anne Marie; Schaaf, André; Pautot, Guy. |
| A sedimentological, mineralogial and geochemical study was made on surface sediment samples associated with nodules in the Tiki Basin (Central South Pacific). The aim of this study was to find variations in the sediment composition with respect to bathymetry and to thus show a relationship between nodule formation and sedimentation. It is now well known that nodules rich, from an economical point of view, are located in this area at a depth more than 4100 meters. The progressive transformation of a carbonate ooze rich in Foraminifera and poor in siliceous biogenic material into a metalifferous sediment has been shown. The CaCO(3), dissolution involves Fe and Mn enrichment of the sediment. The content of these elements becomes stable and independant of... |
| Tipo: Text |
Palavras-chave: Histoire Ifremer. |
| Ano: 1981 |
URL: http://archimer.ifremer.fr/doc/1981/publication-5315.pdf |
| |
|
|
| Pautot, Guy; Hoffert, Michel; Karpoff, Anne Marie; Schaaf, André. |
| The Tiki basin is in the south central Pacific, south of the Marquesas Islands and east of the Tuamotu archipelago. It is bounded nothwards by the Marquesas Fracture Zone and divided in two parts by the topographic heights cunstituting the end to the Tuamotu Fracture Zone. One hundred stations with nodule sampling were occupied by the Group CNEXO-SLN in this area (scale 1O X 10 degrees). The nodule abundance at each station is determined from the weight of nodules brought back by free fall grabs. Chemical analysis were made on each sample (three by station) and the values presented here are the mean values. The parameters : abundance, Ni grade, Cu grade and Mn grade are compared with water depth and topographic features of the area. The main results are :... |
| Tipo: Text |
Palavras-chave: Histoire Ifremer. |
| Ano: 1981 |
URL: http://archimer.ifremer.fr/doc/1981/publication-5307.pdf |
| |
|
|
| Pautot, Guy; Truillet, René; Hoffert, Michel. |
| Tubotomaculum are cylinder-shaped bodies a few centimetres long which can be found in pretty large quantities in the "numidian clays" of the upper Cretacean to Oligocene Mediterranean boundary. We present the observations conducted with electron microscopy. Geochemical and mineralogical analyses have been carried out. The manganese and iron contents are similar to the polymetallic nodules covering the bottom of today's oceans. We continued the comparison with the transition element contents (copper, nickel, cobalt). The Tubotomaculums' core is composed of rhodocrosite and siderite, while their cortex is made of non crystallised iron and manganese. The deposition localization is discussed through the analysis of the surrounding sediments. Different... |
| Tipo: Text |
Palavras-chave: Histoire Ifremer. |
| Ano: 1975 |
URL: http://archimer.ifremer.fr/doc/1975/publication-4979.pdf |
| |
|
|
|
