Consulta: creatorFacets:"Toucanne, Samuel"
Registros recuperados: 53
Data/hora: 11/06/2024 12:12:47

Enhanced surface melting of the Fennoscandian Ice Sheetduring periods of North Atlantic cooling
Provedor de dados: 5
Autores: Boswell, Steven M.; Toucanne, Samuel; Pitel-roudaut, Mathilde; Creyts, Timothy T.; Eynaud, Frédérique; Bayon, Germain.
Heinrich events (HEs) are dramatic episodes of marine-terminating ice discharge and sediment rafting during periods of cold North Atlantic climate. However, the causal chain of events leading to their occurrence is unresolved. Here, we demonstrate that enhanced surface melting of land-terminating margins of the southern Fennoscandian Ice Sheet (FIS) is a recurring feature of Heinrich stadials (HSs), the cold periods during which HEs occur. We use neodymium isotopes to show that the Channel River transported detrital sediments from the interior of eastern Europe to the Bay of Biscay in the northeast Atlantic Ocean at ca. 158–154 ka. Based on similar evidence from the last glacial period, we infer that this interval corresponds to the melting and retreat of...
Tipo: Text
Ano: 2019
URL: https://archimer.ifremer.fr/doc/00499/61065/64596.pdf

External controls on turbidite sedimentation on the glacially-influenced Armorican margin (Bay of Biscay, western European margin)
Provedor de dados: 5
Autores: Toucanne, Samuel; Zaragosi, Sebastien; Bourillet, Jean-francois; Dennielou, Bernard; Jorry, Stephan; Jouet, Gwenael; Cremer, Michel.
Sequence stratigraphic models predict increased sediment delivery to deep-water areas during sea-level lowstand. The Armorican margin (Bay of Biscay, western European margin) is an interesting area to test this hypothesis because the margin has a wide continental shelf, still partly flooded during sea-level lowstand, and the Armorican turbidite system has experienced fluctuating sediment fluxes since the last glacial period. The stratigraphic response of the Armorican turbidite system to sea-level oscillations and climate changes was assessed for the last 35,000 years through the study of the Guilcher, Crozon and Audierne levees. Millenial-timescale resolution chronostratigraphy allowed us to reconstruct the sediment accumulation and turbidite frequency,...
Tipo: Text
Palavras-chave: Armorican margin; Bay of Biscay; Turbidite systems; Turbidity currents; Levee growth; External forcing; Deglaciation; Source-to-sink.
Ano: 2012
URL: http://archimer.ifremer.fr/doc/00070/18147/15708.pdf

Levantine intermediate water hydrodynamic and bottom water ventilation in the northern Tyrrhenian Sea over the past 56,000 years: New insights from benthic foraminifera and ostracods
Provedor de dados: 5
Autores: Minto'O, Charlie Morelle Angue; Bassetti, Maria-angela; Morigi, Caterina; Ducassou, Emmanuelle; Toucanne, Samuel; Jouet, Gwenael; Mulder, Thierry.
Foraminifera and ostracods have been quantitatively studied in core MD01-2472, from the upper continental slope (at water depth of 501 m), to evaluate their relationship with bottom water condition variability and decipher the control of the Levantine Intermediate Water (LIW) current on benthic faunas. The occurrence of reworked ostracod species (originating from the continental shelf) and, the presence of shallow water Elphidium/Ammonia benthic foraminifera are used to estimate the degree of along-slope transport at the core site. This has revealed two intervals of along-slope transport also associated with coarse-grained contourite deposits, deposited during the YD and HS2 episodes. Planktonic-benthic foraminiferal and ostracod assemblages reflect...
Tipo: Text
Palavras-chave: Ostracods; Foraminifera; LIW; Corsica margin.
Ano: 2015
URL: https://archimer.ifremer.fr/doc/00245/35648/34208.pdf

An optimized scheme of lettered marine isotope substages for the last 1.0 million years, and the climatostratigraphic nature of isotope stages and substages
Provedor de dados: 5
Autores: 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

Millennial-Scale Response of a Western Mediterranean River to Late Quaternary Climate Changes: A View from the Deep Sea
Provedor de dados: 5
Autores: Bonneau, Lucile; Jorry, Stephan J.; Toucanne, Samuel; Silva Jacinto, Ricardo; Emmanuel, Laurent.
Although it is widely accepted that erosion and sediment transfer respond to millennial-scale climatic variability, these changes remain difficult to detect in marine sedimentary archives. In the Var sediment-routing system, northwestern Mediterranean Sea, the absence of a continental shelf results in a direct connection between the Var River mouth and the deep basin during both highstand and lowstand conditions. This makes the Var sediment-routing system an ideal target to test whether rivers can transmit climate-driven high-frequency changes in sediment flux to the ocean. On the basis of an unprecedented (centennial-to-millennial-scale) resolution in turbidite sequences, we reconstructed the activity of turbidity current overflows along the deep-sea Var...
Tipo: Text
Ano: 2014
URL: http://archimer.ifremer.fr/doc/00248/35925/34447.pdf

La distribution des assemblages d’ostracodes et de foraminifères benthiques le long des derniers 550 ka dans le bassin Est-Corse, Méditerranée occidentale : une reconstitution paléo-environnementale
Provedor de dados: 5
Autores: 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

Glacial erosion dynamics in a small mountainous watershed (Southern French Alps): A source-to-sink approach
Provedor de dados: 5
Autores: 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

Position of the Polar Front along the western Iberian margin during key cold episodes of the last 45 ka
Provedor de dados: 5
Autores: Eynaud, Frederique; De Abreu, Lucia; Voelker, Antje; Schoenfeld, Joachim; Salgueiro, Emilia; Turon, Jean-louis; Penaud, Aurelie; Toucanne, Samuel; Naughton, Filipa; Goni, Maria Fernanda Sanchez; Malaize, Bruno; Cacho, Isabel.
This paper documents the migration of the Polar Front (PF) over the Iberian margin during some of the cold climatic extremes of the last 45 ka. It is based on a compilation of robust and coherent paleohydrological proxies obtained from eleven cores distributed between 36 and 42 degrees N. Planktonic delta O-18 (Globigerina bulloides), ice-rafted detritus concentrations, and the relative abundance of the polar foraminifera Neogloboquadrina pachyderma sinistral were used to track the PF position. These three data sets, compared from core to core, show a consistent evolution of the sea surface paleohydrology along the Iberian margin over the last 45 ka. We focused on five time slices representative of cold periods under distinct paleoenvironmental forcings:...
Tipo: Text
Palavras-chave: Polar Front; LGM; Heinrich events.
Ano: 2009
URL: https://archimer.ifremer.fr/doc/00218/32909/31415.pdf

A 130,000-year record of Levantine Intermediate Water flow variability in the Corsica Trough, western Mediterranean Sea
Provedor de dados: 5
Autores: Toucanne, Samuel; Jouet, Gwenael; Ducassou, Emmanuelle; Bassetti, Maria-angela; Dennielou, Bernard; Minto'O, Charlie Morelle Angue; Lahmi, Marjolaine; Touyet, Nicolas; Charlier, Karine; Lericolais, Gilles; Mulder, Thierry.
Sortable silt particle-size data and stable isotope analyses from the Corsica Trough, western Mediterranean Sea, provide a continuous palaeoceanographic record of the inflow, ventilation and vertical fluctuations of the Levantine Intermediate Water (LIW) in the northern Tyrrhenian Sea for the last 130,000 years. The results presented herein reveal that climate changes drive the Mediterranean intermediate circulation on Milankovitch to millennial time-scales. Intensified intermediate inflow and ventilation in the Corsica Trough occurred throughout the last glacial interval, with a cold / faster – warm / slower pattern existing between the Dansgaard-Oeschger climatic oscillations (including Heinrich events) and the LIW variability. By contrast, a weak...
Tipo: Text
Palavras-chave: Levantine Intermediate Water; Mediterranean Sea; Thermohaline circulation; Palaeoceanography.
Ano: 2012
URL: https://archimer.ifremer.fr/doc/00054/16506/14023.pdf

Timing of massive ‘Fleuve Manche’ discharges over the last 350 kyr: insights into the European ice-sheet oscillations and the European drainage network from MIS 10 to 2
Provedor de dados: 5
Autores: Toucanne, Samuel; Zaragosi, S.; Bourillet, Jean-francois; Cremer, M.; Eynaud, Frederique; Van Vliet-lanoe, B.; Penaud, A.; Fontanier, C.; Turon, J. L.; Cortijo, E.; Gibbard, P. L.
Continuous high-resolution mass accumulation rates (MAR) and X-ray fluorescence (XRF) measurements from marine sediment records in the Bay of Biscay (NE Atlantic) have allowed the determination of the timing and the amplitude of the ‘Fleuve Manche’ (Channel River) discharges during glacial stages MIS 10, MIS 8, MIS 6 and MIS 4–2. These results have yielded detailed insight into the Middle and Late Pleistocene glaciations in Europe and the drainage network of the western and central European rivers over the last 350 kyr. This study provides clear evidence that the ‘Fleuve Manche’ connected the southern North Sea basin with the Bay of Biscay during each glacial period and reveals that ‘Fleuve Manche’ activity during the glaciations MIS 10 and MIS 8 was...
Tipo: Text
Palavras-chave: Northern north sea; Late weichselian glaciation; Western iberian margin; Abrupt climate change; C 14 YR BP; Deep sea; Heinrich events; Norwegian margin; Millennial scale; English channel.
Ano: 2009
URL: http://archimer.ifremer.fr/doc/00011/12261/9037.pdf

What forced the collapse of European ice sheets during the last two glacial periods (150 ka BP and 18 ka cal BP)? Palynological evidence
Provedor de dados: 5
Autores: 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

Evolution of the danube deep-sea fan since the last glacial maximum: New insights into Black Sea water-level fluctuations
Provedor de dados: 5
Autores: Constantinescu, Adriana; Toucanne, Samuel; Dennielou, Bernard; Jorry, Stephan; Mulder, T.; Lericolais, Gilles.
The Danube Deep-Sea Fan (NW Black Sea) is one of the most developed deep-sea sediment depositional systems in Europe. Although the morphology and the architecture have been widely described in the past years, little is known about the stratigraphy of this depositional system. For the late Quaternary, this results from the lack of significant stratigraphic markers, the scarcity of radiocarbon ages and the difficulty in constraining reservoir ages. Recent robust quantification of reservoir ages has allowed the construction of a new stratigraphic framework for the Black Sea from the end of the last glacial period to the Holocene, thus giving the opportunity to correlate sedimentological and geochemical features previously described on the NW Black Sea margin...
Tipo: Text
Palavras-chave: Danube deep-sea fan; Turbidites; Stratigraphy; Last glacial maximum; Termination 1; Water-level fluctuations.
Ano: 2015
URL: https://archimer.ifremer.fr/doc/00271/38236/64238.pdf

Organic matter isotopes reveal enhanced rainfall activity in Northwestern Mediterranean borderland during warm substages of the last 200 kyr
Provedor de dados: 5
Autores: 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

Sediment routing from shelf to basin floor in the Quaternary Golo System of Eastern Corsica, France, western Mediterranean Sea
Provedor de dados: 5
Autores: 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

The influence of bottom currents on the Zambezi Valley morphology (Mozambique Channel, SW Indian Ocean): In situ current observations and hydrodynamic modelling
Provedor de dados: 5
Autores: Miramontes, Elda; Penven, Pierrick; Fierens, Ruth; Droz, Laurence; Toucanne, Samuel; Jorry, Stephan; Jouet, Gwenael; Pastor, Lucie; Silva Jacinto, Ricardo; Gaillot, Arnaud; Giraudeau, Jacques; Raisson, François.
Mixed turbidite-contourite systems can be found in oceans where bottom currents and turbidity currents interact. The Zambezi turbidite system, located in the Mozambique Channel (SW Indian Ocean), is one of the largest sedimentary systems in the world in length and area of the related catchments. The oceanic circulation in the Mozambique Channel is intense and complex, dominated by eddies flowing southwards and deep currents flowing northwards along the Mozambican margin. Current measurements obtained from moorings at 3400–4050 m water depth in the Zambezi and Tsiribihina valleys show periods of intense currents at the seafloor with peaks of 40–50 cm s−1 that last up to one month and are not related to turbidity currents. These strong bottom-current events...
Tipo: Text
Palavras-chave: Contourite; Turbidity current; Mixed system; Oceanic circulation; Mooring; ADCP; ROMS model; Bedform.
Ano: 2019
URL: https://archimer.ifremer.fr/doc/00476/58743/61269.pdf

The silicon isotopic composition of fine-grained river sediments and its relation to climate and lithology
Provedor de dados: 5
Autores: 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

Distinct control mechanism of fine-grained sediments from Yellow River and Kyushu supply in the northern Okinawa Trough since the last glacial
Provedor de dados: 5
Autores: 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

Late Quaternary geomorphology and sedimentary processes in the Zambezi turbidite system (Mozambique Channel)
Provedor de dados: 5
Autores: 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

Variabilité des transferts sédimentaires vers l'océan prodond à l'échelle du millénaire: le système sédimentaire du Var
Provedor de dados: 5
Autores: Bonneau, Lucile; Jorry, Stephan; Toucanne, Samuel; Emmanuel, Laurent.
A ce jour, très peu d’étude ont mis en évidence l’impact des changements climatiques sur les transferts sédimentaires dans les enregistrements sédimentaires marins. Avec son plateau continental étroit, le système sédimentaire du Var est un site idéal pour l’étude des transferts terre-mer au cours du Quaternaire. Malgré les variations du niveau marin, son « deep-sea-fan » (ride sédimentaire du Var) est resté continuellement alimenté par un canyon directement connecté à l’embouchure du fleuve. L’activité turbiditique récente de ce système, dominée par les courants hyperpycnaux, est étroitement liée aux crues du Var. Le cadre chronostratigraphique de 3 carottes, longues de 20 mètres, prélevées dans les dépôts turbiditiques de la ride sédimentaire du Var a été...
Tipo: Text
Ano: 2013
URL: http://archimer.ifremer.fr/doc/00202/31283/29690.pdf

Land-ocean changes on orbital and millennial time scales and the penultimate glaciation
Provedor de dados: 5
Autores: Margari, Vasiliki; Skinner, Luke C.; Hodell, David A.; Martrat, Belen; Toucanne, Samuel; Grimalt, Joan O.; Gibbard, Philip L.; Lunkka, J. P.; Tzedakis, P. C.
Past glacials can be thought of as natural experiments in which variations in boundary conditions influenced the character of climate change. However, beyond the last glacial, an integrated view of orbital-and millennial-scale changes and their relation to the record of glaciation has been lacking. Here, we present a detailed record of variations in the land-ocean system from the Portuguese margin during the penultimate glacial and place it within the framework of ice-volume changes, with particular reference to European ice-sheet dynamics. The interaction of orbital-and millennial-scale variability divides the glacial into an early part with warmer and wetter overall conditions and prominent climate oscillations, a transitional mid-part, and a late part...
Tipo: Text
Ano: 2014
URL: http://archimer.ifremer.fr/doc/00187/29819/28295.pdf

East Asian monsoon history and paleoceanography of the Japan Sea over the last 460,000 years
Provedor de dados: 5
Autores: Gallagher, Stephen J; Sagawa, Takuya; Henderson, Andrew C. G.; Saavedra-pellitero, Mariem; De Vleeschouwe, David; Black, Heather; Itaki, Takuya; Toucanne, Samuel; Bassetti, Maria-angela; Clemens, Steve; Anderson, William; Alvarez-zarikian, Carlos; Tada, Ryuji.
The Japan Sea is directly influenced by the Asian monsoon, a system that transports moisture and heat across southeast Asia during the boreal summer, and is a major driver of the Earth's ocean‐atmospheric circulation. Foraminiferal and facies analyses of a 460 kyr record from IODP Expedition 346 Site U1427 in the Japan Sea reveal a record of nutrient flux and oxygenation that varied due to sea level and East Asian monsoon intensity. The East Asian summer monsoon (EASM) was most intense during MIS (Marine Isotope Stage) 5e, 7e, 9e and 11c when the Tsushima Warm Current flowed into an unrestricted well mixed normal salinity Japan Sea. Whereas East Asian winter monsoon (EAWM) conditions dominated MIS 2, 4, 6 and 8 when sea level minima restricted the Japan...
Tipo: Text
Palavras-chave: Tsushima Warm Current; Pleistocene; Holocene; Paleoceanography; East Asian summer monsoon; East Asian winter monsoon.
Ano: 2018
URL: http://archimer.ifremer.fr/doc/00444/55591/57215.pdf

Response to Comments on "Intensifying Weathering and Land Use in Iron Age Central Africa"
Provedor de dados: 5
Autores: Bayon, Germain; Dennielou, Bernard; Etoubleau, Joel; Ponzevera, Emmanuel; Toucanne, Samuel; Bermell, Sylvain.
Tipo: Text
Ano: 2012
URL: http://archimer.ifremer.fr/doc/00092/20327/18004.pdf

The Ponto-Caspian basin as a final trap for southeastern Scandinavian Ice-Sheet meltwater
Provedor de dados: 5
Autores: Tudryn, Alina; Leroy, Suzanne A. G.; Toucanne, Samuel; Gibert-brunet, Elisabeth; Tucholka, Piotr; Lavrushin, Yuri A.; Dufaure, Olivier; Miska, Serge; Bayon, Germain.
This paper provides new data on the evolution of the Caspian Sea and Black Sea from the Last Glacial Maximum until ca. 12 cal kyr BP. We present new analyses (clay mineralogy, grain-size, Nd isotopes and pollen) applied to sediments from the river terraces in the lower Volga, from the middle Caspian Sea and from the western part of the Black Sea. The results show that during the last deglaciation, the Ponto-Caspian basin collected meltwater and fine-grained sediment from the southern margin of the Scandinavian Ice Sheet (SIS) via the Dniepr and Volga Rivers. It induced the deposition of characteristic red-brownish/chocolate-coloured illite-rich sediments (Red Layers in the Black Sea and Chocolate Clays in the Caspian Sea) that originated from the Baltic...
Tipo: Text
Palavras-chave: Caspian sea; Black sea; SIS deglaciation; Early Khvalynian transgression; Chocolate clays; Red layers; Clay minerals; Neodymium isotopes; Pollen; Late Pleistocene.
Ano: 2016
URL: http://archimer.ifremer.fr/doc/00345/45605/45225.pdf

From platform top to adjacent deep sea: New source-to-sink insights into carbonate sediment production and transfer in the SW Indian Ocean (Glorieuses archipelago)
Provedor de dados: 5
Autores: Jorry, Stephan; Jouet, Gwenael; Edinger, Evan N.; Toucanne, Samuel; Counts, John W.; Miramontes, Elda; Courgeon, Simon; Riveiros, Natalia Vázquez; Le Roy, Pascal; Camoin, Gilbert F.
Over the past ten years, a huge amount of source-to-sink studies have aimed to unravel the tectonic, climatic and other processes that shape the landscape from mountains to the deep ocean. Interestingly, these studies have been mainly dedicated to siliciclastic or mixed systems, for which the connection between drainage basins, continental shelves, slope and basin environments are often well constrained. Here we present a study focusing on a source-to-sink study dedicated to a pure carbonate system, located in the SW Indian Ocean (Glorieuses archipelago). Extensive field sampling and geophysical acquisition across the carbonate platform have allowed us to estimate the composition, the lateral variability, and volumes of neritic sands deposited on the...
Tipo: Text
Palavras-chave: Carbonate platform; Coral reef; Calciturbidite; Aragonite; Carbonate budget; Indian Ocean.
Ano: 2020
URL: https://archimer.ifremer.fr/doc/00607/71879/70574.pdf

Activity of the turbidite levees of the Celtic-Armorican margin (Bay of Biscay) during the last 30,000 years: Imprints of the last European deglaciation and Heinrich events
Provedor de dados: 5
Autores: Toucanne, Samuel; Zaragosi, S; Bourillet, Jean-francois; Naughton, F; Cremer, M; Eynaud, F; Dennielou, Bernard.
High-resolution sedimentological and micropaleontological studies of several deep-sea cores retrieved from the levees of the Celtic and Armorican turbidite systems (Bay of Biscay - North Atlantic Ocean) allow the detection of the major oscillations of the British-Irish Ice Sheet (BIIS) and 'Fleuve Manche' palaeoriver discharges over the last 30,000 years, which were mainly triggered by climate changes. Between 30 and 20 cal ka, the turbiditic activity on the Celtic-Annorican margin was weak, contrasting with previous stratigraphic models which predicted a substantial increase of sediment supply during low sea-level stands. This low turbidite deposit frequency was most likely the result of a weak activity of the 'Fleuve Manche' palaeoriver and/or of a...
Tipo: Text
Palavras-chave: Turbidites; Heinrich events; LGM; Last deglaciation; Palaeoriver; Fleuve Manche; British irish ice sheet; Bay of Biscay.
Ano: 2008
URL: http://archimer.ifremer.fr/doc/2008/publication-3729.pdf

High-resolution and high-precision correlation of dark and light layers in the Quaternary hemipelagic sediments of the Japan Sea recovered during IODP Expedition 346
Provedor de dados: 5
Autores: Tada, Ryuji; Irino, Tomohisa; Ikehara, Ken; Karasuda, Akinori; Sugisaki, Saiko; Xuan, Chuang; Sagawa, Takuya; Itaki, Takuya; Kubota, Yoshimi; Lu, Song; Seki, Arisa; Murray, Richard W.; Alvarez-zarikian, Carlos; Anderson, William T., Jr.; Bassetti, Maria-angela; Brace, Bobbi J.; Clemens, Steven C.; Da Costa Gurgel, Marcio H.; Dickens, Gerald R.; Dunlea, Ann G.; Gallagher, Stephen J; Giosan, Liviu; Henderson, Andrew C. G.; Holbourn, Ann E.; Kinsley, Christopher W.; Lee, Gwang Soo; Lee, Kyung Eun; Lofi, Johanna; Lopes, Christina I. C. D.; Saavedra-pellitero, Mariem; Peterson, Larry C.; Singh, Raj K.; Toucanne, Samuel; Wan, Shiming; Zheng, Hongbo; Ziegler, Martin.
The Quaternary hemipelagic sediments of the Japan Sea are characterized by centimeter-to decimeter-scale alternation of dark and light clay to silty clay, which are bio-siliceous and/or bio-calcareous to a various degree. Each of the dark and light layers are considered as deposited synchronously throughout the deeper (&gt; 500 m) part of the sea. However, attempts for correlation and age estimation of individual layers are limited to the upper few tens of meters. In addition, the exact timing of the depositional onset of these dark and light layers and its synchronicity throughout the deeper part of the sea have not been explored previously, although the onset timing was roughly estimated as similar to 1.5 Ma based on the result of Ocean Drilling Program...
Tipo: Text
Palavras-chave: Quaternary sediments; Japan Sea; Inter-site correlation; High-resolution age model; IODP; Expedition 346; U1424; U1425; U1426; U1430.
Ano: 2018
URL: https://archimer.ifremer.fr/doc/00437/54817/56292.pdf

Environmental Hf–Nd isotopic decoupling in World river clays
Provedor de dados: 5
Autores: Bayon, Germain; Skonieczny, Charlotte; Delvigne, Camille; Toucanne, Samuel; Bermell, Sylvain; Ponzevera, Emmanuel; Andre, Luc.
The hafnium and neodymium radiogenic isotope systems behave differently during Earth surface processes, causing a wide dispersion of Hf and Nd isotopic compositions in sediments and other sedimentary rocks. The decoupling between Hf and Nd isotopes in sediments is generally attributed to a combination of preferential sorting of zircon during sediment transport and incongruent weathering processes on continents. In this study, we analysed size-fractions of sediment samples collected near the mouth of 53 rivers worldwide to better understand the factors controlling the distribution of Hf and Nd isotopes in sediments. Our results for rivers draining old cratonic areas and volcanic provinces demonstrate that both granite and basalt weathering can lead to...
Tipo: Text
Palavras-chave: Hafnium isotopes; Neodymium; Rivers; Clays; Weathering; Climate.
Ano: 2016
URL: http://archimer.ifremer.fr/doc/00310/42094/41479.pdf

Processes controlling a volcaniclastic turbiditic system during the last climatic cycle: Example of the Cilaos deep-sea fan, offshore La Réunion Island
Provedor de dados: 5
Autores: Sisavath, Emmanuelle; Mazuel, Aude; Jorry, Stephan; Babonneau, Nathalie; Bachelery, Patrick; De Voogd, Beatrice; Salpin, Marie; Emmanuel, Laurent; Beaufort, Luc; Toucanne, Samuel.
The present study focused on turbidite sedimentation in the Cilaos turbidite system, a volcaniclastic deep-sea fan recently recognized offshore La Réunion Island. A set of piston cores was collected in order to establish the stratigraphy of this fan and to examine the processes controlling the turbidite sedimentation off the Cilaos cirque (Piton des Neiges volcanic massif) over the last climatic cycle. Two main phases of turbidite activity were identified, during the ca 140–127 ka and 30–0 ka periods, coinciding with the two last glacial–interglacial transitions (i.e., Terminations II and I). In addition to changes in climate and eustatic sea-level, these periods coincide with a low effusive volcanic activity of the Piton des Neiges volcano. The high...
Tipo: Text
Palavras-chave: Turbidites; La Reunion Island; Indian Ocean; Late Quaternary; Volcaniclastic system.
Ano: 2012
URL: http://archimer.ifremer.fr/doc/00105/21659/19383.pdf

A 1.2 Ma record of glaciation and fluvial discharge from the West European Atlantic margin
Provedor de dados: 5
Autores: Toucanne, Samuel; Zaragosi, S.; Bourillet, Jean-francois; Gibbard, P. L.; Eynaud, F.; Giraudeau, J.; Turon, J. L.; Cremer, M.; Cortijo, E.; Martinez, P.; Rossignol, L.
The correlation of continental sedimentary records with the marine isotope stratigraphy is a challenge of central importance in Quaternary stratigraphy, particularly in Western Europe where long records of glaciation on land areas are particularly rare. Here we demonstrate for the first time the interrelationship of events during the last 1.2 Ma in an ocean-sediment core from the Bay of Biscay (NE Atlantic), SW of the Channel. The identification of discharge variations from tributary river systems to the 'Fleuve Manche' palaeoriver during glacio-eustatic sea-level lowstands demonstrates the correlation of the marine sediment stratigraphy to the expansion and recession of the European ice-sheets. The amplitude and chronology of European ice-sheet...
Tipo: Text
Palavras-chave: Middle pleistocene transition; Ice sheet dynamics; Sea level; Climate change; North Atlantic; English channel; Heinrich events; Fleuve manche; Deep; Origin.
Ano: 2009
URL: http://archimer.ifremer.fr/doc/2009/publication-6956.pdf

Influence of early diagenesis on geotechnical properties of clay sediments (Romania, Black Sea)
Provedor de dados: 5
Autores: Ballas, Gregory; Garziglia, Sebastien; Sultan, Nabil; Pelleter, Ewan; Toucanne, Samuel; Marsset, Tania; Riboulot, Vincent; Ker, Stephan.
The geotechnical properties of clay sediments were investigated using laboratory and in-situ measurements as part of the geohazard assessment in the Romanian sector of the Black Sea affected by landslides and seafloor deformation features. The sediments were characterized as predominantly high plastic silty clay of high compressibility, low undrained shear strength, low cohesion and moderate sensitivity. A shallow increase in shear strength exceeding the general trend could have been reconciled with evidence for the precipitation of iron sulfides and calcium carbonates related to early diagenetic reactions of sulfate reduction (e.g. cryptic sulfur cycle) and anaerobic oxidation of methane. Comparison of the compression behaviour of natural and...
Tipo: Text
Palavras-chave: Lacustrine clay sediment; Structured material; Sulfur cement; Carbonate cement; Early diagenesis; Weak layer.
Ano: 2018
URL: https://archimer.ifremer.fr/doc/00439/55064/56545.pdf

Rare earth elements and neodymium isotopes in sedimentary organic matter
Provedor de dados: 5
Autores: Freslon, Nicolas; Bayon, Germain; Toucanne, Samuel; Bermell, Sylvain; Bollinger, Claire; Chéron, Sandrine; Etoubleau, Joel; Germain, Yoan; Khripounoff, Alexis; Ponzevera, Emmanuel; Rouget, Marie Laure.
We report rare earth element (REE) and neodymium (Nd) isotope data for the organic fraction of sediments collected from various depositional environments, i.e. rivers (n=25), estuaries (n=18), open-ocean settings (n=15), and cold seeps (n=12). Sedimentary Organic Matter (SOM) was extracted using a mixed hydrogen peroxide/nitric acid solution (20%-H2O2 – 0.02M-HNO3), after removal of carbonate and oxy-hydroxide phases with dilute hydrochloric acid (0.25M-HCl). A series of experimental tests indicate that extraction of sedimentary organic compounds using H202 may be complicated occasionally by partial dissolution of sulphide minerals and residual carbonates. However, this contamination is expected to be minor for REE because measured concentrations in H2O2...
Tipo: Text
Palavras-chave: Organic matter; Rare earth elements; REE; Neodymium isotopes; ΕNd; Sediment; Boundary Exchange; Paleoceanography.
Ano: 2014
URL: http://archimer.ifremer.fr/doc/00191/30250/28682.pdf

Linking Danube River Activity to Alpine Ice-Sheet Fluctuations during the Last Glacial (ca. 33-17 ka BP): insights into the continental signature of Heinrich Stadials
Provedor de dados: 5
Autores: Martinez-lamas, Ruth; Toucanne, Samuel; Debret, Maxime; Riboulot, Vincent; Deloffre, Julien; Boissier, Audrey; Cheron, Sandrine; Pitel, Mathilde; Bayon, Germain; Giosan, Liviu; Soulet, Guillaume.
Offshore archives retrieved from marine/lacustrine environments receiving sediment from large river systems are valuable Quaternary continental records. In the present study, we reconstruct the Danube River activity at the end of the last glacial period based on sedimentological, mineralogical and geochemical analyses performed on long-piston cores from the north-west Black Sea margin. Our data suggest that the Danube River produced hyperpycnal floods throughout the ca. 33-17 ka period. Four main periods of enhanced Danube flood frequency, each of 1.5-3 kyr duration, are recorded at ca. 32.5 30.5 ka (equivalent to the first part of Heinrich Stadial HS 3), at ca. 29-27.5 ka (equivalent to Greenland Stadial 4), at ca. 25.3-23.8 ka (equivalent to HS 2) and at...
Tipo: Text
Palavras-chave: Danube river; Floods; Hyperpycnites; Alpine ice sheet; Heinrich stadials; Seasonality; Black sea.
Ano: 2020
URL: https://archimer.ifremer.fr/doc/00613/72556/71612.pdf

Inferring denudation variations from the sediment record; an example of the last glacial cycle record of the Golo Basin and watershed, East Corsica, western Mediterranean sea
Provedor de dados: 5
Autores: Calves, Gerome; Toucanne, Samuel; Jouet, Gwenael; Charrier, Simon; Thereau, Estelle; Etoubleau, Joel; Marsset, Tania; Droz, Laurence; Bez, M.; Abreu, V.; Jorry, Stephan; Mulder, T.; Lericolais, Gilles.
Geophysical data and sampling of the Golo Basin (East Corsica margin) provide the opportunity to study mass balance in a single drainage system over the last 130 kyr, by comparing deposited sediments in the sink and the maximum eroded volume in the source using total denudation proxies. Evaluation of the solid sediments deposited offshore and careful integration of uncertainties from the age model and physical properties allow us to constrain three periods of sedimentation during the last climatic cycle. The peak of sedimentation initiated during Marine Isotopic Stage (MIS) 3 (ca. 45 ka) and lasted until late in MIS 2 (ca. 18 ka). This correlates with Mediterranean Sea palaeoclimatic records and the glaciation in high altitude Corsica. The yield of solid...
Tipo: Text
Ano: 2013
URL: http://archimer.ifremer.fr/doc/00087/19779/17480.pdf

Ice core evidence for decoupling between midlatitude atmospheric water cycle and Greenland temperature during the last deglaciation
Provedor de dados: 5
Autores: 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

A new midshelf record in the northern Bay of Biscay (NE Atlantic, CBT-CS11 core): sedimentological, geochemical and palynological data over the last 7 kyrs
Provedor de dados: 5
Autores: 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

Consistently dated Atlantic sediment cores over the last 40 thousand years
Provedor de dados: 5
Autores: 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

The impact of the last European deglaciation on the deep-sea turbidite systems of the Celtic-Armorican margin (Bay of Biscay)
Provedor de dados: 5
Autores: Zaragosi, Sébastien; Bourillet, Jean-francois; Eynaud, Frédérique; Toucanne, Samuel; Denhard, Benjamin; Van Toer, Aurélie; Lanfumey, Valentine.
The compilation of results obtained on three giant piston cores from the Whittard, Shamrock and Guilcher turbidite levees reveals a high-resolution stratigraphic record for the Bay of Biscay. Due to the abundance of reworked sediments in these sedimentary environments, a specific methodological approach, based on an X-ray-assisted subsampling phase associated with sedimentological, geochemical and micropalaeontological analyses, was implemented. With an accurate chronological framework, this multi-proxy investigation provides observations on the 'Fleuve Manche' palaeoriver and the British-Irish Ice Sheet (BIS) histories over the last 20,000 years. The results obtained highlight the direct influence of the decay of the BIS on the Bay of Biscay deep-sea...
Tipo: Text
Palavras-chave: Sedimentation; Glaciation; Turbidity; Deep sea; Bay of Biscay; French Atlantic margin.
Ano: 2006
URL: http://archimer.ifremer.fr/doc/2006/publication-2142.pdf

Tracking rainfall in the northern Mediterranean borderlands during sapropel deposition
Provedor de dados: 5
Autores: Toucanne, Samuel; Mintoo, Charlie Morelle Angue; Fontanier, Christophe; Bassetti, Maria-angela; Jorry, Stephan; Jouet, Gwenael.
The role of mid-latitude precipitation in the hydrological forcing leading to the deposition of sapropels in the Mediterranean Sea remains unclear. The new GDEC-4-2 borehole, East Corsica margin (northern Tyrrhenian Sea), provides the first precisely dated evidence for enhanced rainfall in the Western Mediterranean during warm intervals of interglacial periods over the last 547 kyr. Comparison of GDEC-4-2 proxy records with pollen sequences and speleothems from the central and eastern Mediterranean reveals that these pluvial events were regional in character and occurred probably in response to the intensification of the Mediterranean storm track along the northern Mediterranean borderlands in autumn/winter. Our dataset suggests that the timing of maxima...
Tipo: Text
Palavras-chave: Mediterranean; Rainfall; Interglacials; Sapropel.
Ano: 2015
URL: http://archimer.ifremer.fr/doc/00287/39804/38301.pdf

Human impact overwhelms long-term climate control of weathering and erosion in southwest China
Provedor de dados: 5
Autores: Wan, Shiming; Toucanne, Samuel; Clift, Peter D.; Zhao, Debo; Bayon, Germain; Yu, Zhaojie; Cai, Guanqiang; Yin, Xuebo; Revillon, Sidonie; Wang, Dawei; Li, Anchun; Li, Tiegang.
During the Holocene there has been a gradual increase in the influence of humans on Earth systems. High-resolution sedimentary records can help us to assess how erosion and weathering have evolved in response to recent climatic and anthropogenic disturbances. Here we present data from a high-resolution (∼75 cm/k.y.) sedimentary archive from the South China Sea. Provenance data indicate that the sediment was derived from the Red River, and can be used to reconstruct the erosion and/or weathering history in this river basin. Accelerator mass spectrometry 14C dating provides direct age control and reveals coherent variations in clay mineralogy, geochemistry, and terrigenous flux, indicative of strong chemical weathering and physical erosion during the...
Tipo: Text
Ano: 2015
URL: http://archimer.ifremer.fr/doc/00266/37754/37175.pdf

Millennial-scale fluctuations of the European Ice Sheet at the end of the last glacial, and their potential impact on global climate
Provedor de dados: 5
Autores: Toucanne, Samuel; Soulet, Guillaume; Freslon, Nicolas; Jacinto, Ricardo Silva; Dennielou, Bernard; Zaragosi, Sebastien; Eynaud, Frederique; Bourillet, Jean-francois; Bayon, Germain.
Reconstructing Northern Hemisphere ice-sheet oscillations and meltwater routing to the ocean is important to better understand the mechanisms behind abrupt climate changes. To date, research efforts have mainly focused on the North American (Laurentide) ice-sheets (LIS), leaving the potential role of the European Ice Sheet (EIS), and of the Scandinavian ice-sheet (SIS) in particular, largely unexplored. Using neodymium isotopes in detrital sediments deposited off the Channel River, we provide a continuous and well-dated record for the evolution of the EIS southern margin through the end of the last glacial period and during the deglaciation. Our results reveal that the evolution of EIS margins was accompanied with substantial ice recession (especially of...
Tipo: Text
Palavras-chave: European ice-sheet; Channel River; Meltwater; Deglaciation; Neodymium; Termination.
Ano: 2015
URL: https://archimer.ifremer.fr/doc/00272/38346/36675.pdf

Comments to Westaway and Bridgland - 'Causes, consequences and chronology of large-magnitude palaeoflows in Middle and Late Pleistocene river systems of northwest Europe'
Provedor de dados: 5
Autores: 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

Reconstruction des transferts sédimentaires en provenance du système glaciaire de Mer d'Irlande et du paléofleuve Manche au cours des derniers cycles climatiques
Provedor de dados: 5
Autores: Toucanne, Samuel.
The Pleistocene has been period of fluctuating climate accompanied by prominent sea-level lowstands during the glacial intervals, when massive continental ice sheets extended from mountainous to lowland European areas. The retreat of the shoreline on the extensive present-day shallow continental shelf of the southern part of the British Isles induced the appearance of the 'Fleuve Manche' palaeoriver, one of the largest systems that drained the European continent. Sedimentary records from the Bay of Biscay offer an independent record allowing the reconstruction of the freshwater and sediment discharges of the 'Fleuve Manche', and the possibility of detecting the imprint of surrounding ice-sheet oscillations and attendant modification of hinterland drainage...
Tipo: Text
Palavras-chave: Land sea correlations; European fluvial system; Glacial Irish Sea system; 'Fleuve Manche' palaeoriver; Ice sheets; Glaciations; Climate; Pleistocene; Turbidite systems; Sediment transfer; Bay of Biscay; Corrélations terre mer; Réseau de drainage européen; Système glaciaire de Mer d'Irlande; Fleuve Manche; Calottes glaciaires; Glaciations; Climat; Pléistocène; Systèmes turbiditiques; Transferts sédimentaires; Golfe de Gascogne.
Ano: 2008
URL: http://archimer.ifremer.fr/doc/2008/these-6328.pdf

Geochemical provenance of sediments from the northern East China Sea document a gradual migration of the Asian Monsoon belt over the past 400,000 years
Provedor de dados: 5
Autores: Beny, Francois; Toucanne, Samuel; Skonieczny, Charlotte; Bayon, Germain; Ziegler, Martin.
The reconstruction of the long-term evolution of the East Asian Monsoon remains controversial. In this study, we aim to give a new outlook on this evolution by studying a 400 kyr long sediment record (U1429) from the northern East China Sea recovered during IODP Expedition 346. Neodymium isotopic ratios and rare earth element concentrations of different grain-size fractions reveal significant provenance changes of the sediments in the East China Sea between East Asian continental sources (mainly Yellow River) and sediment contributions from the Japanese Archipelago. These provenance changes are interpreted as the direct impact of sea level changes, due to the reorganization of East Asian river mouth locations and ocean circulation on the East China Sea...
Tipo: Text
Palavras-chave: Monsoon; Eastern Asia; East China sea; Quaternary; Radiogenic isotopes; Neodymium; Rare earth elements.
Ano: 2018
URL: https://archimer.ifremer.fr/doc/00439/55088/56791.pdf

Are deep-sea ecosystems surrounding Madagascar threatened by land-use or climate change?
Provedor de dados: 5
Autores: 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

The first estimation of Fleuve Manche palaeoriver discharge during the last deglaciation: Evidence for Fennoscandian ice sheet meltwater flow in the English Channel ca 20-18 ka ago
Provedor de dados: 5
Autores: 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

New constraints on European glacial freshwater releases to the North Atlantic Ocean
Provedor de dados: 5
Autores: 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

Rare earth elements and neodymium isotopes in world river sediments revisited
Provedor de dados: 5
Autores: 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

Monsoonal Forcing of European Ice-Sheet Dynamics During the Late Quaternary
Provedor de dados: 5
Autores: 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

Intensifying Weathering and Land Use in Iron Age Central Africa
Provedor de dados: 5
Autores: 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
Ano: 2012
URL: http://archimer.ifremer.fr/doc/00069/18031/15574.pdf

Abrupt drainage cycles of the Fennoscandian Ice Sheet
Provedor de dados: 5
Autores: 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

Sea-level control on turbidite activity in the Rhone canyon and the upper fan during the Last Glacial Maximum and early Deglacial
Provedor de dados: 5
Autores: 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

Evolution of the Danube Deep-Sea Fan since the Last Glacial Maximum: insights into water level fluctuations in the Black Sea
Provedor de dados: 5
Autores: 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
Ano: 2014
URL: http://archimer.ifremer.fr/doc/00202/31277/29684.pdf

Continental-scale transport of sediments by the Baltic Ice Stream elucidated by coupled grain size and Nd provenance analyses
Provedor de dados: 5
Autores: 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 (&lt;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