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| Lesuer, P; Tastet, J P; Weber, O; Sinko, Ja. |
| The mud-patch located in the western part of the Gironde Estuary system comprises a lenticular sedimentary body 420 km super(2) in area, oriented NE-SW at a depth ranging between 30 and 75 m. Its thickness does not exceed 4 m; it fills a light depression in a substrate composed of palimpsest shelly pebbles to find sand deposits. The deposition of this mud-patch from the original estuarine suspended matter began less than 2000 years ago, when the sea reached its present-day level. The sediments are silty-clayey, organized in several centimetrical to decimetrical fining-up sequences, more silty at the base of the mud-patch. Such rythmic deposits are characteristics of a reworking by storm or strong wave activity. These sequences show a seaward evolution. The... |
| Tipo: Text |
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| Ano: 1991 |
URL: http://archimer.ifremer.fr/doc/00267/37871/35952.pdf |
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| Dubrulle, C; Jouanneau, J; Lesueur, P; Bourillet, Jean-francois; Weber, O. |
| The study area, "La Grande Vasiere" (LGV), stretches out on the French Atlantic continental shelf (at ca. 100 m water depth), along 250 km from the Glenan Islands at the north to the southwest of Rochebonne at the south. Box-cores were sampled in this mid-shelf area during four cruises in June 1995, and in April, June and September 2002. They were investigated using sedimentologicat approaches (X-radiographs and grain-size analyses) and radionuclide studies (Pb-210 geochronology and excess Th-234). The main results are: (1) the surficial sediments are generally organized into a decimetrescale fining up sequence which can be the result of extreme storms; (2) an upper mixing layer of 7-20cm reflects an important biological benthic activity and/or the impact... |
| Tipo: Text |
Palavras-chave: Bay of Biscay; Continental shelf; Sedimentation rate; Radionuclides; Fine sediment fraction; Mud. |
| Ano: 2007 |
URL: http://archimer.ifremer.fr/doc/2007/publication-3539.pdf |
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| Latouche, C; Jouanneau, J M; Lapaquellerie, Y; Maillet, N; Weber, O. |
| The southern Biscay shelf is a typical example of a continental margin submitted to a macrotidal regime and the heavy sedimentary fluxes of continental provenance. The aim of this study was to determine the manner in which clay sedimentation is organized on the margin and to evaluate the impact of both river-borne inputs and marine hydrodynamic activity. It was established that the distribution of clay minerals (in the order of frequence: micas, chlorites, illites and smectites) is upset by the interconnection of several sedimentary processes: discontinuous river-borne discharges (richer in smectites); the mixture of newly-arrived material with fine fractions (rich in micas and chlorites) resulting from the reworking of remnant material that represents the... |
| Tipo: Text |
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| Ano: 1991 |
URL: http://archimer.ifremer.fr/doc/00268/37889/35970.pdf |
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| Gadel, F; Jouanneau, Jm; Weber, O; Serve, L; Comellas, L. |
| Mud fields located In the inner part of shelves in front of large estuaries are preferential environments for the investigation of the mechanisms and evolution in time of the supply of such sedimentary bodies. The study of different constituents of the particulate organic matter trapped in the sediments of the West Gironde mud patch contributes to the knowledge of the input origins. This study was carried out with different techniques, including pyrolysis-gas chromatography-mass spectrometry and high performance liquid chromatography, on samples from a core collected in the centre of the mud field. At the bottom of the core, the increase of sugars, amino-sugars and some aromatic hydrocarbons may indicate a more marine character of organic components. The... |
| Tipo: Text |
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| Ano: 1997 |
URL: http://archimer.ifremer.fr/doc/00093/20426/18093.pdf |
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| Grousset, Fe; Cortijo, E; Huon, S; Herve, L; Richter, T; Burdloff, D; Duprat, J; Weber, O. |
| Theories explaining the origin of the abrupt, massive discharges of ice-rafted detritus (IRD) into the glacial North Atlantic (the Heinrich layers (HLs)) generally point to the Laurentide ice sheet as the sole source of these events, until it was found that the IRDs also originated from Icelandic and European ice sheets [Bond and Lotti, 1995; Snoeckx er al., 1999; Grousset et al., 2000]. This apparent contradiction must be reconciled as it raises fundamental questions about the mechanism(s) of HL origin. We have analyzed two similar to 12 cm thick HLs in an ultrahigh-resolution mode (1-2 century intervals) in a mid-Atlantic ridge piston core. The delta O-18 record (N. pachyderma left coiling) reveals strong excursions induced by the melting of the... |
| Tipo: Text |
Palavras-chave: Climate and interannual variability; Climate dynamics; Radiogenic isotope geochemistry. |
| Ano: 2001 |
URL: https://archimer.ifremer.fr/doc/00221/33190/31786.pdf |
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