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| Registros recuperados: 53 | |
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| Toucanne, Samuel; Zaragosi, S.; Eynaud, F.; Bourillet, Jean-francois; Lericolais, Gilles; Gibbard, P. L.. |
| Westaway and Bridgland (Earth Surface Processes and Landforms 35: 1071–1094, 2010) discuss the causes, the consequences and the chronology of large-magnitude palaeoflows in Pleistocene river systems of northwest Europe. Based on their calculations, these authors suggest that the combined effects of meltwater from Alpine glaciers, rainfall, snowmelt and melting of permafrost during Heinrich Events (HEs) explain the large-magnitude discharges of the Fleuve Manche palaeoriver which punctuated the last glacial period. This comment identifies some approximations and inconsistencies regarding (i) the timing of the last massive Fleuve Manche palaeoriver discharge and its relation to the de-glacial pattern of the British-Irish Ice Sheet (Point 1); (ii) the... |
| Tipo: Text |
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| Ano: 2011 |
URL: http://archimer.ifremer.fr/doc/00041/15205/12532.pdf |
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| Fontanier, Christophe; Mamo, Briony; Toucanne, Samuel; Bayon, Germain; Schmidt, Sabine; Deflandre, Bruno; Dennielou, Bernard; Jouet, Gwenael; Garnier, Eline; Sakai, Saburo; Lamas, Ruth Martinez; Duros, Pauline; Toyofuku, Takashi; Sale, Aurelien; Belleney, Deborah; Bichon, Sabrina; Boissier, Audrey; Cheron, Sandrine; Pitel, Mathilde; Roubi, Angelique; Rovere, Mickael; Gremare, Antoine; Dupre, Stephanie; Jorry, Stephan. |
| In this short communication, we present a multidisciplinaty study of sedimentary records collected from a deep-sea interfluve proximal to the mouths of major northwestern Madagascan rivers. For the last 60 years, the seafloor has been repeatedly disturbed by the deposition of organic rich, tropical, terrestrial sediments causing marked reductions in benthic biodiversity. Increased soil erosion due to local land-use, deforestation and intensifying tropical cyclones are potential causes for this sedimentary budget and biodiversity shift. Our marine sedimentary records indicate that until now, these conditions have not occurred within the region for at least 20,000 years. |
| Tipo: Text |
Palavras-chave: Multidisciplinary study; Benthic foraminifera; Land-use; Tropical cyclones. |
| Ano: 2018 |
URL: https://archimer.ifremer.fr/doc/00413/52488/53276.pdf |
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| Toucanne, Samuel; Zaragosi, Sebastien; Bourillet, Jean-francois; Marieu, Vincent; Cremer, Michel; Kageyama, Masa; Van Vliet-lanoe, Brigitte; Eynaud, Frederique; Turon, Jean-louis; Gibbard, Philip L.. |
| The Fleuve Manche (English Channel) palaeoriver represents the largest river system that drained the European continent during Pleistocene lowstands, particularly during the Elsterian (Marine Isotope Stage 12) and Saalian Drenthe (MIS 6) glaciations when extensive ice advances into the North Sea area forced the central European rivers to flow southwards to the Bay of Biscay (NE Atlantic). Numerous long piston cores and high-resolution acoustic data from the northern Bay of Biscay have been correlated using a well-constrained chronostratigraphical framework, and for the first time allow the estimation of the discharge of the Fleuve Manche palaeoriver at the end of the last glacial period (i.e. Weichselian). Our results, discussed in the light of... |
| Tipo: Text |
Palavras-chave: Fleuve Manche palaeoriver; English Channel; Sediment and meltwater discharge; European ice sheet; Deglaciation; Termination 1; North Sea area; European drainage network. |
| Ano: 2010 |
URL: http://archimer.ifremer.fr/doc/00002/11310/7858.pdf |
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| Eynaud, Frederique; Malaize, Bruno; Zaragosi, Sebastien; De Vernal, Anne; Scourse, James; Pujol, Claude; Cortijo, Elsa; Grousset, Francis E.; Penaud, Aurelie; Toucanne, Samuel; Turon, Jean-louis; Auffret, Gerard. |
| During the late Quaternary, both external and internal forcings have driven major climatic shifts from glacial to interglacial conditions. Nonlinear climatic steps characterized the transitions leading to these extrema, with intermediate excursions particularly well expressed in the dynamics of the Northern Hemisphere cryosphere. Here we document the impact of these dynamics on the north-eastern North Atlantic Ocean, focussing on the 35-10 ka interval. Sea-surface salinities have been reconstructed quantitatively based on two independent methods from core MD95-2002, recovered from the northern Bay of Biscay adjacent to the axis of the Manche paleoriver outlet and thus in connection with proximal European ice sheets and glaciers. Quantitative... |
| Tipo: Text |
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| Ano: 2012 |
URL: http://archimer.ifremer.fr/doc/00086/19762/20100.pdf |
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| Bayon, Germain; Toucanne, Samuel; Skonieczny, Charlotte; Andre, L.; Bermell, Sylvain; Cheron, Sandrine; Dennielou, Bernard; Etoubleau, Joel; Freslon, Nicolas; Gauchery, T.; Germain, Yoan; Jorry, Stephan; Menot, G.; Monin, L.; Ponzevera, Emmanuel; Rouget, M. -l.; Tachikawa, K.; Barrat, Jean-alix. |
| Over the past decades, rare earth elements (REE) and their radioactive isotopes have received tremendous attention in sedimentary geochemistry, as tracers for the geological history of the continental crust and provenance studies. In this study, we report on elemental concentrations and neodymium (Nd) isotopic compositions for a large number of sediments collected near the mouth of rivers worldwide, including some of the world’s major rivers. Sediments were leached for removal of non-detrital components, and both clay and silt fractions were retained for separate geochemical analyses. Our aim was to re-examine, at the scale of a large systematic survey, whether or not REE and Nd isotopes could be fractionated during Earth surface processes. Our results... |
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| Ano: 2015 |
URL: http://archimer.ifremer.fr/doc/00276/38733/37249.pdf |
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| Kaboth-bahr, Stefanie; Bahr, Andre; Zeeden, Christian; Toucanne, Samuel; Eynaud, Frederique; Jimenez-espejo, Francisco; Rohl, Ursula; Friedrich, Oliver; Pross, Joerg; Lowemark, Ludvig; Lourens, Lucas J.. |
| The dynamics of Northern Hemisphere ice sheets during Late Quaternary glacials have yet been dominantly examined from a Laurentide Ice Sheet perspective, which helped shaping the idea of moisture-starved glacials and small-scale ice volume variability. However, the waxing and waning of the European Ice Sheet (EIS) casts doubt on this perception. Understanding EIS dynamics under glacial boundary conditions is crucial because its meltwater pulses influence global climate by weakening deepwater formation in the North Atlantic Ocean. Here we show that the advection of subtropical water toward the continental margin of western Europe lead to enhanced moisture availability on the continent and fueled the growth of EIS lobes during glacials. This warm-water... |
| Tipo: Text |
Palavras-chave: Mediterranean Outflow variability; European Ice Sheet dynamics; Marine‐terrestrial feedback in the Euro‐Mediterranean realm; Glacial climate variability; Low‐latitude forcing of high‐latitude glaciations. |
| Ano: 2018 |
URL: https://archimer.ifremer.fr/doc/00457/56831/58657.pdf |
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| Bayon, Germain; Dennielou, Bernard; Etoubleau, Joel; Ponzevera, Emmanuel; Toucanne, Samuel; Bermell, Sylvain. |
| About 3000 years ago, a major vegetation change occurred in Central Africa, when rainforest trees were abruptly replaced by savannas. The consensus is that the forest disturbance was caused by climate change. We show here that chemical weathering in Central Africa, reconstructed from geochemical analyses of a marine sediment core, intensified abruptly at the same period, departing significantly from the long-term weathering fluctuations related to the Late Quaternary climate. Evidence that this weathering event was also contemporaneous with the migration of Bantu-speaking farmers across Central Africa suggests that human land-use intensification at that time already had a significant impact on the rainforest. |
| Tipo: Text |
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| Ano: 2012 |
URL: http://archimer.ifremer.fr/doc/00069/18031/15574.pdf |
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| Soulet, Guillaume; Menot, Guillemette; Bayon, Germain; Rostek, Frauke; Ponzevera, Emmanuel; Toucanne, Samuel; Lericolais, Gilles; Bard, Edouard. |
| Continental ice sheets are a key component of the Earth’s climate system, but their internal dynamics need to be further studied. Since the last deglaciation, the northern Eurasian Fennoscandian Ice Sheet (FIS) has been connected to the Black Sea (BS) watershed, making this basin a suitable location to investigate former ice-sheet dynamics. Here, from a core retrieved in the BS, we combine the use of neodymium isotopes, high-resolution elemental analysis, and biomarkers to trace changes in sediment provenance and river runoff. We reveal cyclic releases of meltwater originating from Lake Disna, a proglacial lake linked to the FIS during Heinrich Stadial 1. Regional interactions within the climate–lake–FIS system, linked to changes in the availability of... |
| Tipo: Text |
Palavras-chave: Ice dynamics; Meltwater routing; European hydrographic network. |
| Ano: 2013 |
URL: http://archimer.ifremer.fr/doc/00134/24489/22516.pdf |
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| Lombo Tombo, Swesslath; Dennielou, Bernard; Berne, Serge; Bassetti, Maria-angela; Toucanne, Samuel; Jorry, Stephan; Jouet, Gwenael; Fontanier, Christophe. |
| The timing, routing and processes of sediment transfer from the continents to the oceans at millennial time-scale are still largely unknown. The potential of turbidite systems (dominantly deposited during sea-level lowstands) to record global or regional environmental fluctuations is usually under-exploited because of the difficulty to obtain robust chronostratigraphic constraints in turbiditic deposits, and therefore to tie changes in sedimentary processes to environmental fluctuations. We were able to obtain a millennial-scale chronostratigraphy based on oxygen isotopes of the scarce foraminifera preserved in turbiditic deposits of the Rhone Turbidite System within the Western Mediterranean. Our results show that 1) objective criteria can be defined for... |
| Tipo: Text |
Palavras-chave: Rhone Turbidite System; Turbidites; Hyperpycnite; Sea level; Last Glacial Maximum; Western Mediterranean. |
| Ano: 2015 |
URL: https://archimer.ifremer.fr/doc/00266/37712/35730.pdf |
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| Constantinescu, Adriana; Toucanne, Samuel; Dennielou, Bernard; Jorry, Stephan; Panin, Nicolae; Lericolais, Gilles. |
| The Danube deep-sea fan is one of the most extensive deep-sea sedimentary systems in Europe. It lies in the base of slope of the north-western margin of the Black Sea, in front of Viteaz Canyon. Since the work of Popescu (2002) the detailed morphology and architecture of the fan is well known. During lowstand periods, the fan was fed by the Viteaz Canyon, which was directly connected to the Danube River. The fan has developed an impressive channel-levees network which is characterized by seven major channel avulsions (Popescu, 2002, Lericolais et al., 2013). Despite the numerous sedimentary cores retrieved during the Blason (1998, 2002) and Assemblage (2004) oceanographic cruises, the details of the factors controlling the turbiditic activity of the Danube... |
| Tipo: Text |
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| Ano: 2014 |
URL: http://archimer.ifremer.fr/doc/00202/31277/29684.pdf |
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| Boswell, Steven; Toucanne, Samuel; Creyts, Timothy T.; Hemming, Sidney R.. |
| We introduce a methodology for determining the transport distance of subglacially comminuted and entrained sediments. We pilot this method on sediments from the terminal margin of the Baltic Ice Stream, the largest ice stream of the Fennoscandian Ice Sheet during the Last Glacial Maximum. A strong correlation (R2 = 0.83) between the εNd and latitudes of circum-Baltic river sediments enables us to use εNd as a calibrated measure of distance. The proportion of subglacially transported sediments in a sample is estimated from grain size ratios in the silt fraction (<63 μm). Coupled εNd and grain size analyses reveal a common erosion source for the Baltic Ice Stream sediments located near the Åland sill, more than 850 km upstream from the terminal moraines.... |
| Tipo: Text |
Palavras-chave: Fennoscandian Ice Sheet; Baltic Ice Stream; Provenance; Epsilon Nd; Grain size; EMMA. |
| Ano: 2018 |
URL: https://archimer.ifremer.fr/doc/00434/54567/57539.pdf |
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| Registros recuperados: 53 | |
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