|
|
|
| Registros recuperados: 53 | |
|
|
| Landais, Amaelle; Capron, Emilie; Masson-delmotte, Valerie; Toucanne, Samuel; Rhodes, Rachael; Popp, Trevor; Vinther, Bo; Minster, Benedicte; Prie, Frederic. |
| The last deglaciation represents the most recent example of natural global warming associated with largescale climate changes. In addition to the long-term global temperature increase, the last deglaciation onset is punctuated by a sequence of abrupt changes in the Northern Hemisphere. Such interplay between orbital-and millennial-scale variability is widely documented in paleoclimatic records but the underlying mechanisms are not fully understood. Limitations arise from the difficulty in constraining the sequence of events between external forcing, high-and low-latitude climate, and environmental changes. Greenland ice cores provide sub-decadal-scale records across the last deglaciation and contain fingerprints of climate variations occurring in different... |
| Tipo: Text |
|
| Ano: 2018 |
URL: https://archimer.ifremer.fr/doc/00462/57349/59446.pdf |
| |
|
|
| Zhao, Debo; Wan, Shiming; Toucanne, Samuel; Clift, Peter D.; Tada, Ryuji; Revillon, Sidonie; Kubota, Yoshimi; Zheng, Xufeng; Yu, Zhaojie; Huang, Jie; Jiang, Hanchao; Xu, Zhaokai; Shi, Xuefa; Li, Anchun. |
| High-resolution multi-proxy records, including clay minerals and Sr-Nd-Pb isotopes of the clay-sized silicate fraction of sediments from IODP Site U1429 in the northern Okinawa Trough, provide reliable evidence for distinct control mechanism on fine-grained sediments input from the Yellow River and the southern Japanese Islands to the northern Okinawa Trough since 34 ka BP. Provenance analysis indicates that the sediments were mainly derived from the Yellow River and the island of Kyushu. Since the last glacial, clay-sized sediments transported from the Yellow River to the study site were strongly influenced by sea-level fluctuation. During low sea-level stage (∼34‒14 ka BP), the paleo-Yellow River mouth was positioned closer to the northern Okinawa... |
| Tipo: Text |
Palavras-chave: Okinawa Trough; Clay-sized sediments; Yellow River; Kyushu Island; Sea-level change; Kuroshio Current; Tsushima Warm Current. |
| Ano: 2017 |
URL: http://archimer.ifremer.fr/doc/00393/50413/51129.pdf |
| |
|
|
| Pasquier, Virgil; Toucanne, Samuel; Sansjofre, Pierre; Dixit, Yama; Revillon, Sidonie; Mokeddem, Zohra; Rabineau, Marina. |
| In this study we use bulk sediment organic matter stable isotopes (δ13Corg and δ15N) to examine the nature and timing of preserved organic matter in borehole PRGL1-4 from Northwestern Mediterranean Sea. This region is known as a transitional zone between the North Atlantic atmospheric circulation and the North African monsoon system. In the Gulf of Lion (SE France), increased inputs of organic matter from sediment-laden rivers occurred during warm substages of the last 200 kyr (MIS 5e, 5c, and 5a; MIS 6d, and 6b). Increased terrestrial organic matter are inferred from organic carbon isotopic composition (δ13Corg), and are interpreted as resulting from enhanced rainfall over the Rhone river catchment area. Such increase in terrestrial organic carbon induced... |
| Tipo: Text |
Palavras-chave: Mediterranean; Rainfall; North Atlantic oscillation; Organic matter; North Mediterranean borderland; Sapropel. |
| Ano: 2019 |
URL: https://archimer.ifremer.fr/doc/00473/58421/61116.pdf |
| |
|
|
| Angue Minto’o, Charlie Morelle; Bassetti, Maria-angela; Toucanne, Samuel; Jouet, Gwenael. |
| The study of Quaternary sediments covering the last 550 kyr from the borehole GDEC-4-2, East-Corsica basin, was performed through the study of benthic meiofaunal assemblages (ostracoda and benthic foraminifera) whose distribution responds to climate changes, and glacial–interglacial variability in particular. The interglacial ostracod group is mainly composed of the Argilloecia acuminata, Cytheropteron alatum, Henryhowella sp., Polycope sp. and Cytherella sp., which indicate an enhanced surface productivity and possibly high bottom water temperature during these warm intervals. Benthic foraminifera, such as Hoeglundina elegans, Sigmoilopsis schlumbergeri, Bigenerina nodosaria and Hyalinea balthica are predominant during interglacial periods and also show... |
| Tipo: Text |
Palavras-chave: Est-Corse; Ostracode; Foraminifère benthique; Groupe allochtone; East-Corsica; Ostracoda; Benthic foraminifera; Allochthonous group. |
| Ano: 2016 |
URL: http://archimer.ifremer.fr/doc/00313/42426/42030.pdf |
| |
|
|
| Waelbroeck, Claire; Lougheed, Bryan C.; Vazquez Riveiros, Natalia; Missiaen, Lise; Pedro, Joel; Dokken, Trond; Hajdas, Irka; Wacker, Lukas; Abbott, Peter; Dumoulin, Jean-pascal; Thil, François; Eynaud, Frédérique; Rossignol, Linda; Fersi, Wiem; Albuquerque, Ana Luiza; Arz, Helge; Austin, William E. N.; Came, Rosemarie; Carlson, Anders E.; Collins, James A.; Dennielou, Bernard; Desprat, Stéphanie; Dickson, Alex; Elliot, Mary; Farmer, Christa; Giraudeau, Jacques; Gottschalk, Julia; Henderiks, Jorijntje; Hughen, Konrad; Jung, Simon; Knutz, Paul; Lebreiro, Susana; Lund, David C.; Lynch-stieglitz, Jean; Malaizé, Bruno; Marchitto, Thomas; Martínez-méndez, Gema; Mollenhauer, Gesine; Naughton, Filipa; Nave, Silvia; Nürnberg, Dirk; Oppo, Delia; Peck, Victoria; Peeters, Frank J. C.; Penaud, Aurélie; Portilho-ramos, Rodrigo Da Costa; Repschläger, Janne; Roberts, Jenny; Rühlemann, Carsten; Salgueiro, Emilia; Sanchez Goni, Maria Fernanda; Schönfeld, Joachim; Scussolini, Paolo; Skinner, Luke C.; Skonieczny, Charlotte; Thornalley, David; Toucanne, Samuel; Rooij, David Van; Vidal, Laurence; Voelker, Antje H. L.; Wary, Mélanie; Weldeab, Syee; Ziegler, Martin. |
| Rapid changes in ocean circulation and climate have been observed in marine-sediment and ice cores over the last glacial period and deglaciation, highlighting the non-linear character of the climate system and underlining the possibility of rapid climate shifts in response to anthropogenic greenhouse gas forcing. To date, these rapid changes in climate and ocean circulation are still not fully explained. One obstacle hindering progress in our understanding of the interactions between past ocean circulation and climate changes is the difficulty of accurately dating marine cores. Here, we present a set of 92 marine sediment cores from the Atlantic Ocean for which we have established age-depth models that are consistent with the Greenland GICC05 ice core... |
| Tipo: Text |
|
| Ano: 2019 |
URL: https://archimer.ifremer.fr/doc/00513/62429/66712.pdf |
| |
|
|
| 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 |
| |
|
|
| 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... |
| Tipo: Text |
|
| Ano: 2015 |
URL: http://archimer.ifremer.fr/doc/00276/38733/37249.pdf |
| |
|
|
| 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 |
|
| Ano: 2011 |
URL: http://archimer.ifremer.fr/doc/00041/15205/12532.pdf |
| |
|
|
| 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 |
| |
|
|
| 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 |
|
| Ano: 2012 |
URL: http://archimer.ifremer.fr/doc/00086/19762/20100.pdf |
| |
|
|
| Penaud, A.; Eynaud, F.; Turon, J. L.; Zaragosi, S.; Malaize, B.; Toucanne, Samuel; Bourillet, Jean-francois. |
| We present a new marine palynological record from the temperate North-eastern Atlantic (core MD03-2692, Celtic-Armorican margin) in the area of influence of the 'Fleuve Manche' paleoriver during glacial times. The runoff of this paleoriver was connected to the glacial history of European ice sheets (including the British Irish Ice Sheet-BIIS). Our study conducted on dinoflagellate cysts assemblages over the last 200 ka, associated with quantification of palynological remains reflecting continental influence (pre-Quaternary dinocysts and micro-algae Pediastrum spp. coenobia), yields detailed insights into the sea-surface paleoenvironments of this sector. More specifically, mechanisms responsible for the origin of unusual deposits of laminated sequences... |
| Tipo: Text |
Palavras-chave: Dinoflagellate cysts; European ice sheets; Celtic Armorican margin; MIS 2 and MIS 6; Terminations I and II. |
| Ano: 2009 |
URL: http://archimer.ifremer.fr/doc/00000/11116/8061.pdf |
| |
|
|
| Bonneau, Lucile; Toucanne, Samuel; Bayon, Germain; Jorry, Stephan; Emmanuel, Laurent; Silva Jacinto, Ricardo. |
| In this study we used major element composition, neodymium isotopes ratios (εNdεNd) and concentration of REE to track and quantify the sediment routing in the Var sedimentary system from source (Southern French Alps) to sink (Ligurian Sea) over the last 50 ka. Our data reveal that changes in sediment sources over that period, associated with concomitant changes in the hyperpycnal (i.e. flood-generated turbidity currents) activity in the Var submarine canyon, were mainly driven by paleoenvironmental conditions in the upper basin and in particular by the presence of glaciers during the last glacial period. Based on this evidence, we determined when and how glacier-derived sediments were produced, then excavated and transferred to the ocean, allowing us to... |
| Tipo: Text |
Palavras-chave: Var; Routing system; Glacial erosion; Source-to-sink. |
| Ano: 2017 |
URL: http://archimer.ifremer.fr/doc/00358/46957/47130.pdf |
| |
|
|
| Sweet, Michael L.; Gaillot, Gwladys T.; Jouet, Gwenael; Rittenour, Tammy M.; Toucanne, Samuel; Marsset, Tania; Blum, Michael D.. |
| How and when sediment moves from shallow marine to deep-water environments is an important and poorly understood control on basin-scale sediment dispersal patterns, the evolution of continental margins, and hydrocarbon exploration in deep-water basins. The Golo River (Eastern Corsica, France), its delta, canyons, and fans provide a unique opportunity to study sediment routing from source to sink in a relatively compact depositional system. We studied this system using an array of high-frequency seismic data, multi-beam bathymetry, and five cores for lithology and age control. Movement of sediment to deep water was controlled by interactions between the Golo River, the Golo Delta, and shelf-penetrating submarine canyons. Sediment moved to deep water when... |
| Tipo: Text |
|
| Ano: 2020 |
URL: https://archimer.ifremer.fr/doc/00589/70154/68234.pdf |
| |
|
|
| Penaud, Aurélie; Ganne, Axelle; Coste, Pierre-olivier; Herlédan, Maïwenn; Durand, Matthieu; Mojtahid, Meryem; Nizou, Jean; Toucanne, Samuel. |
| The high-time resolution (∼70 years in average) multi-proxy analysis conducted on the midshelf core CBT-CS11 (47°46.429’N; 4°25.308’W; 73m depth; 3.96 m long; NW France, S Brittany) revealed the complexity of the palaeohydrological and palaeoclimatic signals recorded over the last 7 kyrs in the recently published paper: “Oceanic versus continental influences over the last 7 kyrs from a midshelf record in the northern Bay of Biscay (NE Atlantic)” [1]. This study presents the whole CBT-CS11 dataset discussed in [1] including sedimentological (XRF and grain-size (total from [1] and CaCO3-free from [2]) analyses), geochemical (oxygen and carbon stable isotopes on two different benthic foraminiferal species: Ammonia falsobeccarii from [1] and Cibicides... |
| Tipo: Text |
Palavras-chave: Holocene; NE Atlantic Ocean; Pollen assemblages; Dinoflagellate cyst assemblages; Stable isotopes; Grain-size analysis; XRF. |
| Ano: 2020 |
URL: https://archimer.ifremer.fr/doc/00610/72209/71003.pdf |
| |
|
|
| Railsback, L. Bruce; Gibbard, Philip L.; Head, Martin J.; Voarintsoa, Ny Riavo G.; Toucanne, Samuel. |
| A complete and optimized scheme of lettered marine isotope substages spanning the last 1.0 million years is proposed. Lettered substages for Marine Isotope Stage (MIS) 5 were explicitly defined by Shackleton (1969), but analogous substages before or after MIS 5 have not been coherently defined. Short-term discrete events in the isotopic record were defined in the 1980s and given decimal-style numbers, rather than letters, but unlike substages they were neither intended nor suited to identify contiguous intervals of time. Substages for time outside MIS 5 have been lettered, or in some cases numbered, piecemeal and with conflicting designations. We therefore propose a system of lettered substages that is complete, without missing substages, and optimized to... |
| Tipo: Text |
Palavras-chave: Substages; Stages; Marine isotope stages; MIS; Chronology; Chronostratigraphy; Climatostratigraphy. |
| Ano: 2015 |
URL: https://archimer.ifremer.fr/doc/00251/36216/35796.pdf |
| |
|
|
| 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 |
| |
|
| |
|
|
| Fierens, Ruth; Droz, Laurence; Toucanne, Samuel; Raisson, François; Jouet, Gwenael; Babonneau, Nathalie; Miramontes Garcia, Elda; Landurain, Steven; Jorry, Stephan. |
| The morphology and present-day sediment distribution of the Zambezi turbidite system was investigated using new bathymetric and sub-bottom profiler data as part of the PAMELA research project. The Zambezi turbidite system is composed of two depositional systems: a channelized fan (the Zambezi Fan) and a semi-confined fan (in the lntermediate Basin). The Zambezi Fan includes the Zambezi Valley, which is deeply incised in the Mozambique Channel and is more than three times as large and deep as the great Tanzanian and North Atlantic Mid-Ocean channels. The erosion in the Zambezi Valley is evidenced by its V-shaped morphology and the existence of a U-shaped thalweg affected by several generations of incisions. Based on echo facies and cores from literature,... |
| Tipo: Text |
Palavras-chave: Zambezi turbidite system; Late Quaternary; Multibeam bathymetry; Sub-bottom seismic profiles. |
| Ano: 2019 |
URL: https://archimer.ifremer.fr/doc/00483/59425/62240.pdf |
| |
|
| |
|
|
| Bayon, Germain; Delvigne, C.; Ponzevera, Emmanuel; Borges, A. V.; Darchambeau, F.; De Deckker, P.; Lambert, T.; Monin, L.; Toucanne, Samuel; Andre, L.. |
| The δ30Si stable isotopic composition of silicon in soils and fine-grained sediments can provide insights into weathering processes on continents, with important implications on the Si budget of modern and past oceans. To further constrain the factors controlling the distribution of Si isotopes in sediments, we have analysed a large number (n=50) of separate size-fractions of sediments and suspended particulate materials collected near the mouth of rivers worldwide. This includes some of the world’s largest rivers (e.g. Amazon, Congo, Mackenzie, Mississippi, Murray-Darling, Nile, Yangtze) and rivers from the case study areas of the Congo River Basin and Northern Ireland. Silt-size fractions exhibit a mean Si isotopic composition (δ30Si = -0.21 ± 0.19‰; 2... |
| Tipo: Text |
Palavras-chave: World rivers; Congo basin; Northern Ireland; Si isotopes; Clay minerals; Weathering; Temperature; Precipitation. |
| Ano: 2018 |
URL: https://archimer.ifremer.fr/doc/00434/54609/55991.pdf |
| |
| Registros recuperados: 53 | |
|
|
|
