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Registros recuperados: 62
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Tracing marine cryptotephras in the North Atlantic during the last glacial period: Improving the North Atlantic marine tephrostratigraphic framework ArchiMer
Abbott, Peter M.; Griggs, Adam J.; Bourne, Anna J.; Chapman, Mark R.; Davies, Siwan M..
Tephrochronology is increasingly being recognised as a key tool for the correlation of disparate palae-oclimatic archives, underpinning chronological models and facilitating climatically independent comparisons of climate proxies. Tephra frameworks integrating both distal and proximal tephra occurrences are essential to these investigations providing key details on their spatial distributions, geochemical signatures, eruptive sources as well as any available chronological and/or stratigraphic information. Frameworks also help to avoid mis-correlation of horizons and provide important information on volcanic history. Here we present a comprehensive chronostratigraphic framework of 14 tephra horizons from North Atlantic marine sequences spanning 60-25 cal ka...
Tipo: Text Palavras-chave: Quaternary; Palaeoceanography; Tephrochronology; North Atlantic; Tephra framework; Marine cores.
Ano: 2018 URL: https://archimer.ifremer.fr/doc/00495/60702/83611.pdf
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Tracing marine cryptotephras in the North Atlantic during the last glacial period: Protocols for identification, characterisation and evaluating depositional controls ArchiMer
Abbott, Peter M.; Griggs, Adam J.; Bourne, Anna J.; Davies, Siwan M..
Tephrochronology is increasingly being utilised as a key tool for improving chronological models and correlating disparate palaeoclimatic sequences. For many sedimentary environments, however, there is an increased recognition that a range of processes may impart a delay in deposition and/or rework tephra. These processes can affect the integrity of tephra deposits as time-synchronous markers, therefore, it is crucial to assess their isochronous nature, especially when cryptotephras are investigated in a dynamic marine environment. A methodology for the identification and characterisation of marine cryptotephras alongside a protocol for assessing their integrity is outlined. This methodology was applied to a wide network of North Atlantic marine sequences...
Tipo: Text Palavras-chave: Quaternary; Palaeoceanography; Tephrochronology; North Atlantic; Transport and deposition; Marine cores; Glass shard concentrations.
Ano: 2018 URL: https://archimer.ifremer.fr/doc/00495/60700/83609.pdf
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Composition en cires, triglycérides, protéines et sucres du mésozooplancton ArchiMer
Alayse-danet, Anne-marie; Daniel, Jean-yves; Le Coz, Jean-rene.
Analyses effectuées sur le zooplancton total des pêches verticales au WP2 et sur des animaux triés à partir des pêches horizontales (Campagne RCA sur les côtes Atlantiques du Portugal). On ne signale pas de différence significative entre la composition biochimique des populations du large et de la côte
Tipo: Text Palavras-chave: Zooplancton; Milieu marin; Composition chimique; Glucide; Cire animale; Triglycéride; Protéine; Océan Atlantique Nord; Upwelling; Méiofaune; Portugal; France; Zone côtière; Zooplankton; Marine environment; Chemical composition; Carbohydrate; Animal wax; Triglyceride; Proteins; North Atlantic; Upwelling; Meiofauna; Portugal; France; Coastal zone.
Ano: 1983 URL: http://archimer.ifremer.fr/doc/00189/29976/28429.pdf
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Deep-water mass source and dynamic associated with rapid climatic variations during the last glacial stage in the North Atlantic: A multiproxy investigation of the detrital fraction of deep-sea sediments ArchiMer
Ballini, M; Kissel, C; Colin, C; Richter, T.
[1] In order to investigate North Atlantic Deep Water (NADW) dynamics and variability during the last glacial stage, a very high resolution multiproxy analysis of the detrital fraction of sediments deposited during Heinrich event 4 and Dansgaard-Oeschger cycles 8 and 7 has been conducted on three deep-sea cores. These cores are distributed along the path of the North Atlantic Deep Water from the Faeroe Shetland Channel to the Reykjanes ridge and the Irminger basin. The concentration in fine-grained magnetites, the Ti-content, and the smectite percentage within the clay minerals show similar and coeval fluctuations at each site and are comparable from one site to the other. This is the imprint of the detrital fraction originating from the northern basaltic...
Tipo: Text Palavras-chave: Glacial period; Dansgaard-Oeschger cycles; North Atlantic; Bottom water circulation; Magnetic properties; Clay minerals.
Ano: 2006 URL: https://archimer.ifremer.fr/doc/00235/34585/33077.pdf
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Independent tephrochronological evidence for rapid and synchronous oceanic and atmospheric temperature rises over the Greenland stadial-interstadial transitions between ca. 32 and 40 ka b2k ArchiMer
Berben, Sarah M.p.; Dokken, Trond M.; Abbott, Peter M.; Cook, Eliza; Sadatzki, Henrik; Simon, Margit H; Jansen, Eystein.
Understanding the dynamics that drove past abrupt climate changes, such as the Dansgaard-Oeschger (DO) events, depends on combined proxy evidence from disparate archives. To identify leads, lags and synchronicity between different climate system components, independent and robust chronologies are required. Cryptotephrochronology is a key geochronological tool as cryptotephra horizons can act as isochrons linking disparate and/or distant records. Here, we investigated marine sediment core MD99-2284 from the Norwegian Sea to look for previously identified Greenland ice core cryptotephra horizons and define time-parallel markers between the archives. We explored potential secondary transport and depositional mechanisms that could hamper the isochronous...
Tipo: Text Palavras-chave: Quaternary; Paleoclimatology; Paleoceanography; North Atlantic; Sedimentology; Marine cores; Ice cores; Cryptotephrochronology; DO-Events; Synchronization.
Ano: 2020 URL: https://archimer.ifremer.fr/doc/00622/73391/72606.pdf
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The duration of migration of Atlantic Anguilla larvae ArchiMer
Bonhommeau, Sylvain; Castonguay, Martin; Rivot, Etienne; Sabatie, Richard; Le Pape, Olivier.
Oceanic larvae of the European (Anguilla anguilla) and American (A. rostrata) eels have to cross the Atlantic Ocean from the Sargasso Sea to European or North American coasts before entering continental habitats. In some European rivers, eel recruitment is now < 1% of levels in the 1980s. A better understanding of the effects of anthropogenic pressures and environmental fluctuations on eel larvae and subsequent recruitment is a prerequisite to build efficient management plans. The present paper provides insight into the critical oceanic phase of the eel life cycle with a focus on the duration of the larval migration whose estimates varies between 7 months and more than 2 years in both species. Does this range correspond to a natural variability in...
Tipo: Text Palavras-chave: Lagrangian modelling; Leptocephali; North Atlantic; Otoliths; Sargasso Sea.
Ano: 2010 URL: http://archimer.ifremer.fr/doc/00011/12208/9033.pdf
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Long-term trends in fish recruitment in the north-east Atlantic related to climate change ArchiMer
Brunel, Thomas; Boucher, Jean.
This study investigates the temporal correspondence between the main patterns of recruitment variations among north-east Atlantic exploited fish populations and large-scale climate and temperature indices. It is of primary importance to know what changes in fish stock productivity can be expected in response to climate change, to design appropriate management strategies. The dominant patterns of recruitment variation were extracted using a standardized principal component analysis (PCA). The first principal component (PC) was a long-term decline, with a stepwise change occurring in 1987. A majority of Baltic Sea, North Sea, west of Scotland and Irish Sea populations, especially the gadoids, have followed this decreasing trend. On the contrary, some herring...
Tipo: Text Palavras-chave: North Atlantic; Global warming; Fishing impacts; Fish recruitment; Comparative approach; Climate change.
Ano: 2007 URL: http://archimer.ifremer.fr/doc/2007/publication-2636.pdf
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Deep-dwelling foraminifera as thermocline temperature recorders ArchiMer
Cleroux, Caroline; Cortijo, Elsa; Duplessy, Jean-claude; Zahn, Rainer.
We measured the oxygen isotopic composition of the deep-dwelling foraminiferal species G. inflata, G. truncatulinoides dextral and sinistral, and P. obliquiloculata in 29 modern core tops raised from the North Atlantic Ocean. We compared calculated isotopic temperatures with atlas temperatures and defined ecological models for each species. G. inflata and G. truncatulinoides live preferentially at the base of the seasonal thermocline. Under temperature stress, i.e., when the base of the seasonal thermocline is warmer than 16 degrees C, G. inflata and G. truncatulinoides live deeper in the main thermocline. P. obliquiloculata inhabits the seasonal thermocline in warm regions. We tested our model using 10 cores along the Mauritanian upwelling and show that...
Tipo: Text Palavras-chave: Deep-dwelling foraminifera; Depth habitat; Isotopic temperature; Thermocline; North Atlantic; Mauritanian upwelling; Ecological prediction; Stable isotopes; Micropaleontology.
Ano: 2007 URL: https://archimer.ifremer.fr/doc/00236/34727/33178.pdf
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Sources, cycling and transfer of mercury in the Labrador Sea (Geotraces -Geovide cruise) ArchiMer
Cossa, Daniel; Heimburger, L. E.; Sonke, J. E.; Planquette, H.; Lherminier, Pascale; Garcia-ibanez, Maria Isabel; Perez, Ff; Sarthou, G..
The Labrador Sea links the Arctic and North Atlantic oceans and constitutes one of the main entrances of atmospheric inputs into the Ocean's interior. We report here the first high-resolution Hg distribution pattern along a transect from Greenland to Labrador coasts sampled after the 2014 winter convection. Total Hg concentrations in unfiltered (HgTUNF) samples ranged from 0.25 pmol L− 1 to 0.67 pmol L− 1 averaging 0.44 ± 0.10 pmol L− 1 (n = 113, 1σ). Concentrations in filtered samples (HgTF, < 0.45 μm) represented from 62 to 92% of the HgTUNF and exhibited a similar distribution. High HgTUNF concentrations were found (i) in the waters of the Labrador Current, which receive desalted waters from the Canadian Arctic Archipelago, and (ii) in the waters...
Tipo: Text Palavras-chave: Labrador Sea; Mercury; North Atlantic.
Ano: 2018 URL: https://archimer.ifremer.fr/doc/00411/52207/52929.pdf
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Les Eaux Modales du gyre subpolaire de l'Atlantique Nord : origine, formation, variabilité ArchiMer
De Boisseson, Eric.
The subpolar Mode Waters of the North Atlantic ocean play a key role in the general oceanic surface circulation. Their life cycle has only been described from an average of observations over several decades. This description avoids the real time scale of this life cycle and smooths its variaribility. It also does not adress the setting the Mode Water properties. This thesis work deals with these aspects by analysing both the ORCA025-G70 model fields and the observations.The lagrangian analysis of the ORCA025-G70 fields highlights the key role of the North Atlantic current in the life cycle of the Mode Waters. The Mode Waters are fed and carried by this current. They form during the winter mixed layer deepening due to the surface atmospheric fluxes. The...
Tipo: Text Palavras-chave: ORCA025 G70; Lagrangian analysis; Argo; Advection; Atmospheric fluxes; North Atlantic current; Subpolar gyre; North Atlantic; Mode water; ORCA025 G70; Analyse lagrangienne; Argo; Advection; Flux atmosphériques; Courant Nord Atlantique; Gyre subpolaire; Atlantique Nord; Eau modale.
Ano: 2010 URL: http://archimer.ifremer.fr/doc/2010/these-7469.pdf
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Structure of the upper water column in the northwest North Atlantic: Modern versus last glacial maximum conditions ArchiMer
De Vernal, A; Hillaire-marcel, C; Peltier, Wr; Weaver, Aj.
During the Last Glacial Maximum, the northwestern North Atlantic constituted a major conduit for Labrador and Greenland ice sheet meltwaters. Vertical density gradients in its upper water masses have been reconstructed by combining information from transfer functions based on dinocysts and from oxygen isotope measurements (delta(18)O) in planktonic foraminifera. Transfer functions yield temperature and salinity and thus potential density (sigma(theta)) for the warmest (August) and coldest (February) months in the photic zone. The delta(18)O values in different size fractions of epipelagic (Globigerina bulloides) and mesopelagic (Neogloboquadrina pachyderma left-coiled (Np1)) foraminifera allow us to assess sigma(theta) gradients through the pycnocline...
Tipo: Text Palavras-chave: Last Glacial Maximum; LGM; North Atlantic; Salinity; Density; Pycnocline.
Ano: 2002 URL: https://archimer.ifremer.fr/doc/00223/33405/31861.pdf
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Overview of (Sub)mesoscale Ocean Dynamics for the NAAMES Field Program ArchiMer
Della Penna, Alice; Gaube, Peter.
Tipo: Text Palavras-chave: Mesoscale; Eddies; North Atlantic aerosols and marine ecosystems study; North Atlantic; NAAMES; Altimeter; Satellite oceanography; Lagrangian reanalysis.
Ano: 2019 URL: https://archimer.ifremer.fr/doc/00509/62022/66142.pdf
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Full-depth temperature trends in the northeastern Atlantic through the early 21st century ArchiMer
Desbruyeres, D.g.; Mcdonagh, E. L.; King, B. A.; Garry, F. K.; Blaker, A. T.; Moat, B. I.; Mercier, Herle.
The vertical structure of temperature trends in the northeastern Atlantic (NEA) is investigated using a blend of Argo and hydrography data. The representativeness of sparse hydrography sampling in the basin mean is assessed using a numerical model. Between 2003 and 2013, the NEA underwent a strong surface cooling (0–450 m) and a significant warming at intermediate and deep levels (1000 m to 3000 m) that followed a strong cooling trend observed between 1988 and 2003. During 2003–2013, gyre-specific changes are found in the upper 1000 m (warming and cooling of the subtropical and subpolar gyres, respectively), while the intermediate and deep warming primarily occurred in the subpolar gyre, with important contributions from isopycnal heave and water mass...
Tipo: Text Palavras-chave: North Atlantic; Temperature; Observations; Hiatus.
Ano: 2014 URL: http://archimer.ifremer.fr/doc/00236/34677/33026.pdf
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Pectinoidea (Mollusca: Bivalvia) from Iceland Naturalis
Dijkstra, H.H.; Waren, A.; Gudmundsson, G..
The Icelandic pectinoid fauna is reviewed, based on material from the benthic survey programme BIOICE and 17 species are recorded. Similipecten oskarssoni is proposed as a replacement name for Pecten groenlandicus var. minor Locard, 1898 (Propeamussiidae), which is considered a valid species. Lectotypes are designated for Pecten groenlandicus var. minor and Pecten frigidus Jensen, 1904 (Pectinidae). Cyclopecten ambiannulatus Schein, 1989, Parvamussium propinquum (Smith, 1885), Catillopecten eucymatus (Dall, 1898), and Aequipecten opercularis (Linnaeus, 1758) were previously not known from the Icelandic fauna. All species are figured and described and distinguishing characters are discussed. The distribution in Scandinavian and North Atlantic waters is...
Tipo: Article / Letter to the editor Palavras-chave: Pectinoidea; Taxonomy; New species; North Atlantic; Iceland; BIOICE; 42.73.
Ano: 2009 URL: http://www.repository.naturalis.nl/record/410534
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New morphological data on Solariella obscura (Trochoidea: Solariellidae) from New Jersey, USA Rev. Bras. Zool.
Dornellas,Ana Paula S.; Simone,Luiz R.L..
Anatomical data on Solariellaobscura (Couthouy, 1838) are presented and analyzed. The main features of this species, when compared with other known trochoids, are: ctenidium with thick lamellae; enlarged ureter (that may indicate sexual dimorphism) instead of a modified urogenital papilla; odontophore very different from other trochoids such as Calliostoma, Agathistoma, Monodonta, and Gaza, with short m6, large mj and m4 pairs and absent m8 pair and posterior cartilages; esophageal valve surrounding the odontophore ventrally; anterior and mid-esophagus composed of several thin folds and a very wide cerebral ganglion. Solariellaobscura differs from Solariellavaricosa (Mighels & Adams, 1842) by having lower spire, spiral cords weaker on the base and...
Tipo: Info:eu-repo/semantics/article Palavras-chave: Anatomy; Comparative data; North Atlantic; Redescription.
Ano: 2015 URL: http://www.scielo.br/scielo.php?script=sci_arttext&pid=S1984-46702015000200162
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Nd and Pb isotope signatures of the clay-size fraction of Labrador Sea sediments during the Holocene: Implications for the inception of the modern deep circulation pattern ArchiMer
Fagel, N; Hillaire-marcel, C; Humblet, M; Brasseur, R; Weis, D; Stevenson, R.
Nd and Pb isotopes were measured on the fine fraction of one sediment core drilled off southern Greenland. This work aims to reconstruct the evolution of deep circulation patterns in the North Atlantic during the Holocene on the basis of sediment supply variations. For the last 12 kyr, three sources have contributed to the sediment mixture: the North American Shield, the Pan-African and Variscan crusts, and the Mid-Atlantic Ridge. Clay isotope signatures indicate two mixtures of sediment sources. The first mixture (12.2-6.5 ka) is composed of material derived from the North American shield and from a "young'' crustal source. From 6.5 ka onward the mixture is characterized by a young crustal component and by a volcanic component characteristic of the...
Tipo: Text Palavras-chave: Clay-size fraction; Sedimentary mixings; Deep circulation; Nd and Pb isotopes; North Atlantic; Labrador Sea.
Ano: 2004 URL: https://archimer.ifremer.fr/doc/00226/33731/32199.pdf
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Centennial-scale Holocene North Atlantic surface temperatures from Mg/Ca ratios in Globigerina bulloides ArchiMer
Farmer, Elizabeth J.; Chapman, Mark R.; Andrews, Julian E..
A high-resolution record of Mg/Ca ratios from the planktonic foraminifer Globigerina bulloides has been produced for IMAGES core MD99-2251 from the subpolar North Atlantic. The record extends from the Younger Dryas-Preboreal transition through the Holocene at similar to 70 year resolution, with a more detailed section at similar to 20 year resolution through the interval encompassing the major cooling episode 8200 years ago. Mg/Ca derived temperatures show significant variations through the Holocene, with surface temperatures ranging from similar to 8 to 13 degrees C. The onset of the Holocene is marked by an abrupt warming, with a further increase in early Holocene temperatures occurring prior to 9.5 ka. This is followed by a mid-Holocene period of cooler...
Tipo: Text Palavras-chave: Planktonic foraminifera; Mg/Ca; G. bulloides; North Atlantic; Holocene.
Ano: 2008 URL: https://archimer.ifremer.fr/doc/00236/34760/33396.pdf
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The main pycnocline in the North Atlantic subtropical gyre from Argo Data ArchiMer
Feucher, Charlene; Maze, Guillaume; Mercier, Herle.
In the north Atlantic subtropical gyre, the oceanic vertical structure of density is characterized by a region of rapid increase with depth. This layer is called the permanent pycnocline because this density feature is observed throughout the year. The pycnocline is the transition layer between light, low-latitude, surface water masses which are ventilated every winter when penetrated locally by the mixed layer and dense, deeper water masses whose properties are set in the high latitudes and circulate equatorward. In-situ data from the Argo array provide temperature/salinity profiles allowing the characterization in space and time of the permanent pycnocline. We thus developed a new method to characterize its depth, thickness and thermohaline...
Tipo: Text Palavras-chave: Argo; Quality Control; Pattern; Clustering; North Atlantic; Subtropical gyre; Stratification.
Ano: 2014 URL: http://archimer.ifremer.fr/doc/00242/35315/33838.pdf
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La cinématique de l'Atlantique Nord : la question de la déformation intraplaque ArchiMer
Fidalgo González, Luis.
The main features of geodynamic evolution in the North Atlantic and the lithospheric plates surrounding it have been known for a quarter of a century now. However, a number of questions raised by the first models published have still not been clearly answered in detail. Among them, the difficulty in adjusting the domain to the north and the south of the Faeroe-Iceland-Greenland ridge should be highlighted. This study addresses the issue by using fracture zones as the main data for our reconstructions. We show that they accurately bound the kinematical reconstructions. They also enable kinematical reorganisation periods to be studied on the scale of oceans, as well as their duration. Reconstructions carried out on these bases confirm the existence of...
Tipo: Text Palavras-chave: Europa; Africa; North Atlantic; Modelling; Fracture zone; Magnetic anomaly; Ocean crust; Deformation; Plate tectonic; Europe; Afrique; Atlantique Nord; Modélisation; Zone Fracture; Ouverture; Anomalie Magnétique; Croute Oceanique; Déformation; Tectonique Plaque.
Ano: 2001 URL: http://archimer.ifremer.fr/doc/2001/these-1205.pdf
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North Atlantic Western Boundary Currents Are Intense Dissolved Organic Carbon Streams ArchiMer
Fontela, Marcos; Pérez, Fiz F; Mercier, Herle; Lherminier, Pascale.
In the North Atlantic, there are two main western boundary currents related to the Atlantic Meridional Overturning Circulation (AMOC): the Gulf Stream flowing northward and the Deep Western Boundary Current (DWBC) flowing southward. Here we analyze data from the OVIDE section (GO-SHIP A25 Portugal-Greenland 40–60°N) that crosses the DWBC and the northward extension of the Gulf Stream, the North Atlantic Current. We show that North Atlantic western boundary currents play a key role in the transport of dissolved organic matter, specifically dissolved organic carbon (DOC). Revisited transports and budgets of DOC with new available data identify the eastern Subpolar North Atlantic (eSPNA) as an important source of locally produced organic matter for the North...
Tipo: Text Palavras-chave: Dissolved organic carbon; North Atlantic; Carbon budget; Carbon dioxide; Biogeochemistry; Atlantic Meridional Overturning Circulation.
Ano: 2020 URL: https://archimer.ifremer.fr/doc/00661/77268/78702.pdf
Registros recuperados: 62
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