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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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| Peate, Dw; Baker, Ja; Blichert-toft, J; Hilton, Dr; Storey, M; Kent, Ajr; Brooks, Ck; Hansen', H; Pedersen, Ak; Duncan, Ra. |
| We present elemental and isotopic (Sr-Nd-Pb-Hf-Os-He) data on primitive alkalic lavas from the Prinsen af Wales Bjeige, East Greenland. Stratigraphical, compositional and Ar-40-Ar-39 data indicate that this inland alkalic activity was contemporaneous with the upper parts of the main tholeiitic plateau basalts and also postdated them. The alkalic rocks show a marked crustal influence, indicating establishment of new magmatic plumbing systems distinct from the long-lived coastal systems that fed the relatively uncontaminated plateau basalts. The least contaminated lavas have high He-3/He-4 isotope ratios (R/R-A 12.4-18.5), sub-chondritic Os-187/(OSi)-O-88 (0.120-0.126), low epsilonNd(i) (similar to + 4) and epsilonHf(i) (similar to+ 6) that plot below the... |
| Tipo: Text |
Palavras-chave: Alkalic lavas; Flood basalts; High He-3/He-4; East Greenland; Recycled lithosphere; Iceland plume. |
| Ano: 2003 |
URL: https://archimer.ifremer.fr/doc/00224/33507/31953.pdf |
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