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| Gregoire, Gwendoline; Le Roy, Pascal; Ehrhold, Axel; Jouet, Gwenael; Garlan, Thierry. |
| This study details the sedimentary infilling of an original tidal-dominated estuary system during the final stage of the last marine transgression. The Bay of Brest is confined and connects the rivers Elorn and Aulne, to the sea of Iroise by a narrow strait encasing a well preserved paleo-channel. The compilation of high- and very-high-resolution bathymetric and seismic data, constrained by sediments datations, allows us to classify the paleo-morphology of the bay into three stepped domains: the paleo-valley floor surrounded by fluvial terraces, the central plateau, and the shallow embayments. Taking into account the main factors controlling the infilling, including sea-level rise, substratum morphology, and hydrodynamics, the stratigraphic scheme of the... |
| Tipo: Text |
Palavras-chave: Tide-dominated estuary; Incised-valley; Holocene infill; Seismic stratigraphy; Estuarine processes; Bay of Brest. |
| Ano: 2017 |
URL: https://archimer.ifremer.fr/doc/00358/46968/46883.pdf |
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| Lambert, Clement; Penaud, Aurelie; Vidal, Muriel; Klouch, Khadidja; Gregoire, Gwendoline; Ehrhold, Axel; Eynaud, Frederique; Schmidt, Sabine; Ragueneau, Olivier; Siano, Raffaele. |
| For the first time a very high resolution palynological study (mean resolution of 1 to 5 years) was carried out over the last 150 years in a French estuarine environment (Bay of Brest; NW France), allowing direct comparison between the evolution of landscapes, surface water, and human practices on Bay of Brest watersheds, through continental (especially pollen grains) and marine (phytoplanktonic microalgae: cysts of dinoflagellates or dinocysts) microfossils. Thanks to the small size of the watersheds and the close proximity of the depositional environment to the mainland, the Bay of Brest represents an ideal case study for palynological investigations. Palynological data were then compared to published palaeo-genetic analyses conducted on the same core... |
| Tipo: Text |
Palavras-chave: Pollen grains; Dinoflagellate cysts; Estuarine dynamics; River runoff; Climate variability. |
| Ano: 2018 |
URL: https://archimer.ifremer.fr/doc/00410/52110/52813.pdf |
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| Van Vliet-lanoe, Brigitte; Authemayou, Christine; Molliex, Stephane; Field, Michael Hugh; Frechen, Manfred; Le Roy, Pascal; Perrot, Julie; Andrieu-ponel, Valerie; Gregoire, Gwendoline; Hallegouet, Bernard. |
| The Brittany region of France is located in a low seismicity intraplate zone. Most of the instrumented earthquakes are limited to a shallow crustal depth without surface rupture. A paleoseismological analysis was performed on deposits on the Crozon Peninsula and in the Elorn estuary. We highlight hydroplastic deformations induced by liquefaction leading to clay diapirism, which were likely triggered by past earthquakes. This diapirism seems to be frequent in continental nonconsolidated sediments and to develop on the inherited tectonic structures, when a shallow water table and confining layers exist. Timing of deformation is dated using paleoenvironmental data, and electron spin resonance and infrared-stimulated luminescence dating methods. Two seismic... |
| Tipo: Text |
Palavras-chave: Clay diapirism; Liquefaction; Earthquake; Saprolite; Brittany; Variscan structures; Paleoseismology; Intraplate; Middle Pleistocene. |
| Ano: 2019 |
URL: https://archimer.ifremer.fr/doc/00637/74955/76029.pdf |
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| Gregoire, Gwendoline; Ehrhold, Axel; Le Roy, Pascal; Jouet, Gwenael; Garlan, Thierry. |
| Long-studied with respect to its sedimentological features (1897), the Bay of Brest (Western Britanny, France) is a textbook example of a tide-dominated estuary. Characterised by macrotidal conditions, this estuary system is sheltered from the open sea (Iroise Sea) by a narrow strait that partitions the wave tide influences and continental/marine inputs. Sediments are supplied to the bay both by rivers (the Aulne and Elorn rivers) and by marine tidal currents. This study presents new analyses of detailed facies and morphological patterns, based on the integration of multisource data compiling seabed sampling, swath and LIDAR bathymetry, and backscatter imagery. The Main Map, at a scale of 1:90,000, contains (1) a sedimentological distribution using the... |
| Tipo: Text |
Palavras-chave: Morpho-sedimentological cartography; Tide-dominated; Estuary system; Estuarine sedimentation; Backscatter imagery; Bay of Brest. |
| Ano: 2016 |
URL: http://archimer.ifremer.fr/doc/00334/44492/44224.pdf |
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| Lambert, Clement; Vidal, Muriel; Penaud, Aurelie; Combourieu-nebout, Nathalie; Lebreton, Vincent; Ragueneau, Olivier; Gregoire, Gwendoline. |
| Modern palynological investigations (pollen and non-pollen palynomorphs) have been carried out for the first time in the entire Bay of Brest (BB; NW France), a semi-enclosed oceanic basin flooded during the Holocene that today is exposed to both marine (North Atlantic surface waters) and fluvial (Aulne and Elorn rivers) influences. Palynological analyses were conducted on 41 surface sediments collected in several mudded bays where low-energy conditions prevail, allowing for fine particle decantation, and also on 12 moss samples considered to be pollen rain collectors taken on the periphery of the BB. Furthermore, the BB allows a direct comparison between landscapes and fossilized pollen assemblages in sediments thanks to relatively small watersheds and... |
| Tipo: Text |
Palavras-chave: Pollen; Dinocyst; Surface sediment; Estuarine dynamics; Vegetation cover. |
| Ano: 2017 |
URL: https://archimer.ifremer.fr/doc/00382/49371/49784.pdf |
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