Advection de fluides interstitiels dans les series sedimentaires du complexe d'accretion de la Barbade (Leg 110 ODP)

Diagenesis and Hydrology at the New Hebrides Forearc and Intra-Arc Aoba Basin

“…Advection of the deep fluid is required in order for water released below 1.5 km to dilute the fluids at 400 mbsf; elevated water contents near fault zones suggest that advection occurs along the fault planes. Advection along faults of low-Cl water has previously been proposed to explain low-Cl and methane-rich fluid found in the Barbados accretionary wedge (Blanc et al, 1988Gieskes et al, 1990;Vrolijk et al, 1990Vrolijk et al, , 1991. The methane in the Barbados water has been identified as thermogenic based on its isotope ratio and the presence of heavier hydrocarbons supporting a deep origin of the fluids.…”

“…No section of tectonized sediment was observed which would indicate the location of the proto-decollement and the likely flow horizon for accretionary wedge fluids. In contrast to the New Hebrides margin, at the Barbados margin chemical characteristics of fluids recovered from the proto-decollement zone and from sand layers below the proto-decollement seaward of the deformation front suggest that there is active flow from the accretionary wedge (Moore, Mascle, et al, 1987;Blanc et al, 1988;Gieskes et al, 1990;Vrolijk et al, 1990Vrolijk et al, , 1991.…”

“…17), an attribute exhibited by all convergent margins studied (Kastner et al, 1991). Results from a variety of convergent margins (e.g., Blanc et al, 1988Gieskes et al, 1990;Kastner et al, 1990;Le Pichon et al, 1990;Gieskes et al, 1993;Mottl et al, 1993) (µl/L) and reflect liberation of methane at 70°C from 5 cm" 3 of sediment into a 21 cm" 3 vial (Collot, Greene, Stokking, et al, 1992).…”

Eocene Paleogeography of the Southeastern Caribbean: Relations between Sedimentation on the Atlantic Abyssal Plain at Site 672 and Evolution of the South America Margin

“…Furthermore, in some samples, the terrigenous fraction is highly sandy. We observed a significant amount of authigenic carbonate in the middle-upper Eocene sediments, especially in the sandy layers, where pore-water chemistry results suggest that high fluid circulation rates existed (Blanc et al, 1988;Gieskes et al, in press).…”

“…We note that within this siliceous interval, and just above it, most of our samples contain a significant amount of authigenic carbonate (rhodochrosite and dolomite). Their occurrence may be related to the high pore-water circulation that was demonstrated by geochemical studies (Moore, Mascle, et al, 1987;Blanc et al, 1988;Gieskes et al, in press) and by the existence of fluid-escape structures ("veins") within lower Miocene cores. Figure 4B illustrates the general characteristics of the whole interval.…”