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| Roussel, Erwan; Sauvadet, Anne Laure; Allard, Jonathan; Chaduteau, Carine; Richard, Pierre; Cambon Bonavita, Marie-anne; Chaumillon, Eric. |
| In Marennes-Oleron Bay, a macro-tidal bay located on the French Atlantic coast, kilometer-scale acoustic turbidity reveals an accumulation of free gas in the sediment. Large concentrations of organic matter and rapid sedimentation rates provide ideal settings for biogenic methane cycling. We integrate seismic, sedimentologic, biogeochemical and molecular genetic approaches to determine whether microbial methane cycling is involved in this process. Here we show that the acoustic turbidity upper boundary matched with X-ray facies displaying fissures with the highest methane concentrations, demonstrating the existence of methane bubbles in the sediment. 16S rRNA and mcrA gene clone libraries were dominated by sequences affiliated to the three known ANME... |
| Tipo: Text |
Palavras-chave: Sediment; Methane; McrA; 16S rRNA; Archaea. |
| Ano: 2009 |
URL: http://archimer.ifremer.fr/doc/2009/publication-6165.pdf |
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| Poirier, Clement; Sauriau, Pierre-guy; Chaumillon, Eric; Bertin, Xavier. |
| Mollusc death assemblages were recovered in 98 subtidal sampling stations on the seafloor of the shallow Pertuis Charentais Sea (Atlantic coast of France). Taxonomic composition and spatial distribution of death assemblages were investigated, as well as their response to sediment grain size (field data), bottom shear stress (coupled tide and wave hydrodynamic modelling), and sediment budget (bathymetric difference map) Results showed that molluscs are likely to be reliable paleoenvironmental indicators since death assemblages were able to acquire ecological changes within years (decadal-scale taphonomic inertia), and live-dead agreement inferred from existing data on living benthic communities was high, except close to river mouths and intertidal mudflats... |
| Tipo: Text |
Palavras-chave: Benthos; Estuary; Holocene; Paleoecology; Sediment budget; Taphonomy. |
| Ano: 2010 |
URL: http://archimer.ifremer.fr/doc/00017/12814/10260.pdf |
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| Riou, Brieuc; Chaumillon, Eric; Chagu, Catherine; Sabatier, Pierre; Schneider, Jean-luc; Walsh, John-patrick; Zawadzki, Atun; Fierro, Daniela. |
| Following recent tsunamis, most studies have focused on the onshore deposits, while the offshore backwash deposits, crucial for a better understanding of the hydrodynamic processes during such events and offering an opportunity for sedimentary archives of past tsunamis, have mostly been omitted. Here, we present a unique sedimentary record of the backwash from two historical tsunamis sampled in a sheltered bay in American Samoa, namely the 2009 South Pacific Tsunami and the 1960 Great Chilean Earthquake Tsunami. Although not always concomitant with a marked grain size change, backwash deposits are identified by terrestrial geochemical and mineralogical signatures, associated with basal soft sediment micro-deformations. These micro-deformations, including... |
| Tipo: Text |
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| Ano: 2020 |
URL: https://archimer.ifremer.fr/doc/00659/77079/78407.pdf |
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| Riou, Brieuc; Chaumillon, Eric; Schneider, Jean‐luc; Corrège, Thierry; Chagué, Catherine. |
| Extensive bathymetric and two‐dimensional seismic surveys have been carried out and cores collected in Pago Pago Bay (Tutuila, American Samoa) in order to describe and gain a better understanding of the sediment fill of the bay, which was affected by the 2009 South Pacific Tsunami. Eight sedimentary units were identified over the volcanic bedrock. The basal transgressive unit displays retrograding onlaps towards the shore, whereas the overlying seven aggradational layers alternate between four draping units and three pinching out seaward units. ‘Core to seismic’ correlation reveals that draping units are composed of homogeneous silts, while pinching out units are dominated by very coarse coral fragments showing fresh cuts, mixed with Halimeda plates. The... |
| Tipo: Text |
Palavras-chave: Core to seismic correlation; Holocene; Sediment bay-fill; Shallow marine tsunami deposits; Tectonic activity cycles; Tsunami. |
| Ano: 2020 |
URL: https://archimer.ifremer.fr/doc/00501/61231/76154.pdf |
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| Poirier, Clement; Sauriau, Pierre-guy; Chaumillon, Eric; Allard, Jonathan. |
| During the Late Holocene, the rate of sea level rise decreased and climate changes, hydrodynamic processes or anthropogenic impacts became predominant parameters governing the sedimentary infill of estuarine environments. The aim of this study is to describe the response of past benthic mollusc communities to these forcing factors. Mollusc skeletal remains were sampled from three 8000, 5500 and 2600 year-long sedimentary records in the Marennes-Oleron Bay (Atlantic Coast, France), where environmental changes have previously been identified thanks to a combination of very high resolution seismic profiles and sedimentological data. Molluscan assemblages successfully record environmental changes, even at the smallest temporal scale. They provide relevant... |
| Tipo: Text |
Palavras-chave: Atlantic Coast; Sediment core; Palaeoenvironment; Death assemblage; Macrofauna. |
| Ano: 2009 |
URL: http://archimer.ifremer.fr/doc/2009/publication-6833.pdf |
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