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| Bougault, Henri; Joron, Jean-louis; Treuil, Michel. |
| .-Alkali metals prove to be very sensitive to alteration process even if this process is moderate. It is very difficult to use these elements to trace magmatic processes since their concentration may Vary within an homogeneous "unaltered" unit. From all the basaltic units investigated, a classification of "low partition coefficient" elements is presented (Sc, Ti, V, Y, Zr, Nb, La-Tb , Hf, Ta, Th) . The incompatible elements ratios (Y/Tb, Zr/Hf, Nb/Ta) are constant in the samples studied and are nearly equal to the same ratios in chondrites. This is consistent with the existence of an homogeneous primordial mantle at the scale of the North Atlantic, compatible with a chondritic composition of the earth. [NOT CONTROLLED OCR] |
| Tipo: Text |
Palavras-chave: Histoire Ifremer. |
| Ano: 1979 |
URL: http://archimer.ifremer.fr/doc/1979/publication-5253.pdf |
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| Bouilloux, Alexandra; Valet, Jean-pierre; Bassinot, Franck; Joron, Jean-louis; Blanc-valleron, Marie-madeleine; Moreno, Eva; Dewilde, Fabien; Kars, Myriam; Lagroix, France. |
| Large changes in magnetic mineral concentration dependent parameters by more than 1 order of magnitude occur over 50-150 cm intervals in two marine sediment cores from the oxygen minimum zone in the Gulf of Aden. High-resolution sedimentological and chemical analyses indicate that these intervals are not associated with turbiditic events or sediment reworking, they do not result from changes in carbonate dilution or differences in sediment properties, and they do not correspond to volcanic layers. Magnetic mineralogical analyses reveal a change in magnetic mineral concentration from a magnetite-goethite assemblage to pure magnetite within the peak. The peaks almost disappear when the abundance of magnetic minerals is calculated after correcting for the... |
| Tipo: Text |
Palavras-chave: Paleomagnetism; Paleoenvironment; Goethite; Magnetite; Indian ocean. |
| Ano: 2013 |
URL: https://archimer.ifremer.fr/doc/00264/37488/36828.pdf |
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| Auzende, Jean-marie; Boespflug, Xavier; Bougault, Henri; Dosso, Laure; Foucher, Jean-paul; Joron, Jean-louis; Ruellan, Etienne; Sibuet, Jean-claude. |
| Three cruises (POP 1, SEAPSO 3 and SEAPSO 4) carried out during the "Tour du Monde" of the R.V. Jean Charcot allow us to obtain new structural and geochemical data for the Okinawa, North Fiji and Lau basins. Taken together, the structural and geochemical data illustrate a difference in evolution stages of these sites. The less evolved stage is represented by the Okinawa basin, where accretion is evidenced only by volcanic intrusion into a thinned continental crust. The most evolved stage is illustrated in the North Fiji basin, where the present-day accretion can be directly compm·ed to the East Pacific Ridge. The Lau basin displays an intem1ediate stage with a complex system of accretionary ridges. This difference in the evolution stage is translated in... |
| Tipo: Text |
Palavras-chave: Ouest Pacifique; Bassins arriere arc; Structure; Accretion; Geochimie; West Pacific; Back arc basins; Structure; Accretion; Geochemistry. |
| Ano: 1990 |
URL: http://archimer.ifremer.fr/doc/00119/23058/20893.pdf |
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| Boespflug, Xavier; Dosso, Laure; Bougault, Henri; Joron, Jean-louis. |
| Rock samples have been dredged clming S0-35 and SEAPSO JV cruises (1984 and 1985) from cliJTemnl spreading ridges in lhe Lau Basin, soulh-weslern Pacific. They were analyzed for major and lrace elemenls and isotopic ralios (Sr, Nd). Nmlhem Lau Basin samples show N-MORB type characlerislics, bolh in major andlrace elemenls, whereas soulhern Lau Basin ones are differenlialed and show significanl Ta-Nb negalive anomalies in lheir extended REE pallerns, which is characlerislic of subcluclion zones.lsolopic ralios (Sr, Nd) are quile helerogeneous and inlermediale bel ween MORB and island arc values. The norlhern Lau Basin Ridge has geochemical characlerislics suggeslive ofmedio-oceanic lype spreading, whemas lhe soulhem LauBasin Ridge (Valu Pa Ridge) wilh ils... |
| Tipo: Text |
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| Ano: 1990 |
URL: http://archimer.ifremer.fr/doc/00119/23059/20894.pdf |
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