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| Meyzen, Cm; Ludden, Jn; Humler, E; Luais, B; Toplis, Mj; Mevel, C; Storey, M. |
| We report new Sr, Nd, and Pb isotope data for Mid-Ocean Ridge Basalts (MORB) dredged between 35 and 69 degrees E along a similar to 4100 km section of the Southwest Indian Ridge (SWIR), which is one of the slowest spreading ridges of the global mid-ocean ridge system ( full rate of 16 mm yr(-1)). The SWIR appears isotopically more heterogeneous than other mid-ocean ridges over similar length scales and comparable sampling density. Isotopic variations are generally independent of ridge segmentation, and the degree of heterogeneity decreases from west to east. This decrease in heterogeneity correlates with the observed increase in axial depth and decrease in crustal thickness, commonly attributed to decreasing mantle potential temperature. Data for the... |
| Tipo: Text |
Palavras-chave: Southwest Indian Ridge; MORB; Isotopes; Indian Ocean; Lower crust; Mantle. |
| Ano: 2005 |
URL: https://archimer.ifremer.fr/doc/00232/34286/32655.pdf |
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| Charvis, P; Recq, M; Operto, S; Brefort, D. |
| Seismic refraction profiles were carried out in 1983 and 1987 throughout the Kerguelen Isles (southern Indian Ocean, Terres Australes and Antarctiques Francaises, TAAF) and thereafter at sea on the Kerguelen-Heard Plateau during the MD66/KeOBS cruise in 1991. These profiles substantiate the existence of oceanic-type crust beneath the Kerguelen-Heard Plateau stretching from 46 degrees S to 55 degrees S, including the archipelago. Seismic velocities within both structures are in the range of those encountered in 'standard' oceanic crust. However, the Kerguelen Isles and the Kerguelen-Heard Plateau differ strikingly in their velocity-depth structure. Unlike the Kerguelen Isles, the thickening of the crust below the Kerguelen-Heard Plateau is caused by a 17 km... |
| Tipo: Text |
Palavras-chave: Hotspot; Kerguelen; Lower crust; Oceanic islands; Oceanic plateau; Underplating. |
| Ano: 1995 |
URL: https://archimer.ifremer.fr/doc/00297/40791/39809.pdf |
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| Dupre, Stephanie; Cloetingh, Sierd; Bertotti, Giovanni. |
| In the South Gabon Basin, deep multi-channel seismic reflection and gravity modeling analysis have shed light on key features of the structure of the margin. The thinned continental crust beneath the Gabon Margin appears to be composed of two distinct layers, separated by a clear, strong and more or less continuous reflector running in the 7–10 s TWT window. The lower crust is characterized by a higher density, intermediate between the lower values of the upper crust and the denser values of the mantle. The lower crust is irregularly shaped and presents lateral thickness variations along the direction of thinning and along the coast. In the offshore thinned continental domain, the lower and upper crust form a 20–25 km thick body. Crustal thicknesses point... |
| Tipo: Text |
Palavras-chave: Deep seismic; Gravity modeling; Crustal structure; Rifted continental margins; Lower crust; Gabon Margin. |
| Ano: 2011 |
URL: http://archimer.ifremer.fr/doc/00039/15020/12347.pdf |
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