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| Blanc, G; Boulegue, J; Gieskes, Jm. |
| We report here our findings on the chemistry of methane, manganese and chloride dissolved in the interstitial water of the Barbados accretionary complex. The decollement separating the subduction plate from the accretionary wedge is geochemically characterized by high methane and manganese and low chloride concentrations relative to buried seawater. Sandstone layers occurring below the decollement and the compressive structures recording some of the earliest effects of offscraping are also characterized by similar anomalies. A fluid with the same characteristics is also found six kilometres to the east of the deformation front within the oceanic plate. High manganese concentration and low chlorinity also occur in the pore water of the offscraped sediment... |
| Tipo: Text |
Palavras-chave: BARBADOS ACCRETIONARY COMPLEX; INTERSTITIAL WATER; CHEMICAL COMPOSITION; ADVECTION; DIAGENESIS. |
| Ano: 1991 |
URL: http://archimer.ifremer.fr/doc/00101/21262/18873.pdf |
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| Blanc, G; Doussan, C; Thomas, C; Boulegue, J. |
| We present a non-steady-state diffusion and advection model that describes the distribution of methane, manganese and silica concentrations versus depth at sites 671, 676, and 672 of ODP Leg 110 through an oceanic sedimentary pile undergoing horizontal shortening by means of thrust-faults and folds. The model suggests that the distribution of these chemical components above and below fluid flow conduits is controlled by molecular diffusion. Upward fluid advection from the pathways to the surrounding sediments appears to be without significance for this environment (about 1.10(-11) m.s-1, i.e. almost-equal-to 0.3 mm.yr-1). Estimates of the time necessary to produce the diffusion profiles indicate that average ages of the chemical anomalies increase from... |
| Tipo: Text |
Palavras-chave: NUMERICAL MODEL; INTERSTITIAL WATER; DIFFUSION; ADVECTION; DIAGENESIS. |
| Ano: 1993 |
URL: http://archimer.ifremer.fr/doc/00100/21137/18757.pdf |
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| Kawahata, H; Ishizuka, T. |
| Biogenic siliceous and calcareous sediments were drilled at sites 677 and 678 on the flank of Costa Rica Rift in the Panama basin. We analysed DCAA (dissolved combined amino acids) and DFAA (dissolved free amino acids) in the interstitial waters as well as THAA (total hydrolyzable amino acids) in the sediments in order to evaluate the relationship between THAA, DCAA and DFAA. Comparison of the THAA in the sediments and in marine settling particulate matter (Ittekkot et al., 1984 b) showed that the concentration of non-protein amino acids (e. g., beta-alanine, gamma-aminobutyric acid, and ornithine) was much higher in the sediments and that the neutral amino acid fraction was depleted in the sediments. These results, together with the organic carbon... |
| Tipo: Text |
Palavras-chave: BIOGENIC SEDIMENTS; INTERSTITIAL WATER; THAA; DCAA; DFAA. |
| Ano: 1993 |
URL: http://archimer.ifremer.fr/doc/00099/21062/18688.pdf |
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