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4. Influence of northwest Pacific productivity on North Pacific Intermediate Water oxygen concentrations during the Bolling-Allerod interval (14.7-12.9 ka)

Author

Crusius, John, Pedersen, Thomas F., Kienast, Stephanie, Keigwin, Lloyd, and Labeyrie, Laurent

Subjects
Geology -- Research, Earth sciences
Abstract

Elevated productivity in the northwest Pacific is suggested as a new possible control driving past intervals of low-[O.sub.2] intermediate water along the western continental margin of North America. According to this mechanism, [O.sub.2] consumption would occur near the site of formation of North Pacific Intermediate Water (NPIW), due to increased respiration of organic carbon in response to a high-productivity event. Evidence is provided for such a productivity increase during the Bolling-Allerod interval (14.7-12.9 ka), a time when laminated sediments were deposited along the northern California margin. By this mechanism, low-[O.sub.2] events in intermediate waters off the western North American margin could occur without significant changes in the rate of NPIW ventilation. Keywords: laminations, productivity, North Pacific, anoxic environment, continental margin.

Published
2004

5. Long- and short-term carbon fluctuations in the Eastern Mediterranean during the late Holocene

Author

Schilman, Bettina, Almogi-Labin, Ahuva, Bar-Matthews, Miryam, Labeyrie, Laurent, Paterne, Martine, and Luz, Boaz

Subjects
Middle East -- Natural history, Geology, Stratigraphic -- Holocene, Foraminifera -- Analysis, Earth sciences
Abstract

A high-resolution record of carbon isotope changes during the late Holocene was obtained in core GA-112 from the easternmost Mediterranean. Over the past 3600 yr, a gradual [sup.13]C-depletion trend shown by both planktonic and benthic foraminifera corresponds to a global rise in atmospheric C[O.sub.2]. The global and local trends suggest that aridification and biomass destruction in the Nile basin played a major role in the global C[O.sub.2] rise in the late Holocene. Superimposed on the general [delta][sup.13]C trend are four mirror-image cycles in [delta][sup.13]C of planktonic and benthic foraminifera. Higher planktonic [delta][sup.13]C values reflect periods of high productivity off the coast of Israel. Simultaneously, decrease in the benthic [delta][sup.13]C values occurred because of degradation of higher organic-matter fluxes to the sediment. Therefore, large differences between the two records indicate periods of high productivity. The Eastern Mediterranean productivity fluctuations respond to a periodical replenishment of nutrients to the mixed layer via Nile runoff. Historical data of the Nile flood fluctuations for the past ~1400 yr show a remarkable coincidence between high and low Nile floods and high and low Eastern Mediterranean productivity levels, which are correlated with the periodic monsoonal activity over the Nile headwaters. Keywords: Eastern Mediterranean, foraminiferal [delta][sup.13]C, Nile-derived nutrients, productivity cycles, late Holocene.

Published
2001

6. The timing of the last deglaciation in North Atlantic climate records

Author

Waelbroeck, Claire, Duplessy, Jean-Claude, Michel, Elisabeth, Labeyrie, Laurent, Paillard, Didier, and Duprat, Josette

Subjects
Environmental issues, Science and technology, Zoology and wildlife conservation
Abstract

Author(s): Claire Waelbroeck (corresponding author) [1]; Jean-Claude Duplessy [1]; Elisabeth Michel [1]; Laurent Labeyrie [1, 2]; Didier Paillard [1]; Josette Duprat [3] The last deglaciation is a period particularly well [...]

Published
2001
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12. Correlations between climate records from North Atlantic sediments and Greenland ice

Author

Bond, Gerard, Broecker, Wallace, Johnsen, Sigfus, McManus, Jerry, Labeyrie, Laurent, Jouzel, Jean, and Bonani, Georges

Subjects
Greenland -- Environmental aspects, North Atlantic Ocean -- Natural history, Ice sheets -- Environmental aspects, Climatic changes -- Causes of, Environmental issues, Science and technology, Zoology and wildlife conservation
Abstract

Dansgaard-Oeschger events, which are a series of rapid warm and bold oscillations, terminated the final glaciation in Greenland. This is revealed by the oxygen isotope measurements in Greenland. Sea surface temperatures from the North Atlantic sediments over a period of 90,000 years are recorded, and a series of temperature core oscillations, similar to those on ice core record, are noticed. Cooling cycles, which prevail over a period of 10 to 15 kyr, incorporate the ocean temperature shifts. These changes of temperatures indicate that the Dansgaard-Oeschger events terminated the glaciation.

Published
1993

13. Evidence for massive discharges of icebergs into the North Atlantic ocean during the last glacial period

Author

Bond, Gerard, Heinrich, Harmut, Broecker, Wallace, Labeyrie, Laurent, McManus, Jerry, Andrews, John, Huon, Sylvain, Jantschik, Ruediger, Clasen, Silke, Simet, Christine, Tedesco, Kathy, Klas, Mieczyslawa, Bonani, Georges, and Ivy, Susan

Subjects
Climatic changes -- Research, Glacial epoch -- Research, Icebergs -- Research, Marine sediments -- Research, Environmental issues, Science and technology, Zoology and wildlife conservation
Abstract

Sedimentary deposits in the North Atlantic from the most recent ice age contain mineral detritus deposited by icebergs which can be traced to their origin 3,000 kilometers away in eastern Canada. The advance of the icebergs reflects a surface cooling which is difficult to explain. It may be explained by rapid advances in the Laurentide ice sheet, but ice core evidence from Greenland does not corroborate a contemporary decrease in air temperature. Furthermore, the iceberg discharges do not follow Milankovitch orbital periods.

Published
1992

15. The Atlantic Meridional Overturning Circulation as productivity regulator of the North Atlantic Subtropical Gyre

Author

Nave, Sílvia, Lebreiro, Susana, Michel, Elisabeth, Kissel, Catherine, Figueiredo, Maria Ondina, Guihou, Abel, Ferreira, Antonio, Labeyrie, Laurent, Alberto, Ana, Nave, Sílvia, Lebreiro, Susana, Michel, Elisabeth, Kissel, Catherine, Figueiredo, Maria Ondina, Guihou, Abel, Ferreira, Antonio, Labeyrie, Laurent, and Alberto, Ana

Abstract

Spatially extensive and intense phytoplankton blooms observed off Iberia, in satellite pictures, are driven by significant nutrient supply by upper-ocean vertical mesoscale activity rather than by horizontal advection by coastal upwelling. Productivity of oligotrophic regions is still poorly depicted by discrete instrumental and model data sets. The paleoproductivity reconstructions of these areas represent the mean productivity over long periods, bringing new insights into the total biomass fluxes. Here, we present paleoproductivity records from the oceanic Tore Seamount region, covering the period from 140 to 60 ka. They show higher nutrient supplies during Termination II, Marine Oxygen Isotope Stage (MIS) 4, MIS 6, and warming transitions of the MIS 5 sub-stages. The highest nutrient content (higher productivity) in phase with tracers of bottom-water ventilation (benthic δ13C,231Pa/230Th) establishes a strong linkage with variability of Southern Ocean-sourced waters. Low productivity and ventilation over warm sub-stages of MIS 5 respond instead to North Atlantic Deep Water. Assuming that the Tore Seamount is representative of oligotrophic regions, the glacial-interglacial relationship observed between paleoproductivity and Atlantic Meridional Overturning Circulation strength opens new insights into the importance of estimating the total biomass in these regions. The subtropical gyres might play a considerable role in the carbon cycle over (sub-)glacial-interglacial time scales than previously thought.

Published
2019

16. Reconstructing sea surface temperature and salinity using delta18O and alkenone records

Author

Rostek, Frauke, Ruhland, Gotz, Bassinot, Franck C., Muller, Peter J., Labeyrie, Laurent D., Lancelot, Yves, and Bard, Edouard

Subjects
Ocean temperature -- Research, Sea-water -- Composition, Paleoceanography -- Research, Paleoclimatology -- Research, Environmental issues, Science and technology, Zoology and wildlife conservation
Abstract

The abundance of alkenones in certain algae indicates palaeotemperatures. This technique was successfully applied to a sample drawn from the Arabian Sea-Bay of Bengal juncture, supporting and greatly extending previous studies of sea temperature in the region. The resulting 170,000 year record indicates that sea-surface temperature varied between 25.5 and 28 degrees celsius, and that the Indian monsoon varied greatly throughout the end of the latest glacial period.

Published
1993

17. Were the North Atlantic Heinrich events triggered by the behavior of the European ice sheets?

Author

Grousset, Francis E., Pujol, Claude, Labeyrie, Laurent, Auffret, Gerard, and Boelaert, An

Subjects
North Atlantic Ocean -- Environmental aspects, Europe -- Environmental aspects, Ice sheets -- Environmental aspects, Paleoclimatology -- Research, Detritus -- Research, Isotopes -- Research, Mass spectrometry -- Usage, Earth sciences
Abstract

Theories explaining the origin and distribution of Heinrich layers--abrupt, massive discharges of ice-rafted detritus--generally attribute these layers to the Laurentide ice sheet. However, doubt has been cast by the discovery that sediments also originated from European ice sheets. Here we present isotopic (Sr-Nd) fingerprints of Heinrich layers obtained in cores from the European margin. They reveal that for most of the Heinrich layers, the icebergs were calved first from the European ice sheets, predating the Laurentide surges. Accelerator mass spectrometry (.sup.14)C ages reveal that the oceanic Heinrich events were synchronous with their dust equivalents in the Greenland ice cores, implying a direct ocean-atmosphere link. The typical Laurentide surge seems to have occurred over a short time span, after about 1.5 k.y. of iceberg release from the European ice sheets. This suggests that the Laurentide ice sheet responded to a stimulus created by events in the European sector. Keywords: Atlantic Ocean, paleoclimatology, Heinrich events, ice-rafted detritus, St-Nd isotopes.

Published
2000

18. Variations in Atlantic surface ocean paleoceanography, 50°-80°N: A time-slice record of the last 30,000 years

Author

Sarnthein, Michael, Jansen, Eystein, Weinelt, Mara, Arnold, Maurice, Duplessy, Jean Claude, Erlenkeuser, Helmut, Flatøy, Astrid, Johannessen, Gro, Johannessen, Truls, Jung, Simon, Koc, Nalan, Labeyrie, Laurent, Maslin, Mark, Pflaumann, Uwe, Schulz, Hartmut, Samthein, Michael, Duplessy, Jean, Flat0y, Astrid, Kiel University, Geological Institute [Bergen], University of Bergen (UiB), Centre des Faibles Radioactivités, Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Centre National de la Recherche Scientifique (CNRS), Godwin Laboratory for Palaeoclimate Research, Department of Earth Sciences [Cambridge, UK], University of Cambridge [UK] (CAM)-University of Cambridge [UK] (CAM), Institut für Geologie [Hannover], and Leibniz Universität Hannover=Leibniz University Hannover

Subjects
[SDU.OCEAN]Sciences of the Universe [physics]/Ocean, Atmosphere, geography, geography.geographical_feature_category, Paleontology, Last Glacial Maximum, Oceanography, Paleoceanography, Interglacial, Glacial period, Younger Dryas, Ice sheet, [SDU.ENVI]Sciences of the Universe [physics]/Continental interfaces, environment, Quaternary, Meltwater, Geology
Abstract

International audience; Eight time slices of surface-water paleoceanography were reconstructed from stable isotope and paleotemperature data to evaluate late Quaternary changes in density, current directions, and sea-ice cover in the Nordic Seas and NE Atlantic. We used isotopic records from 110 deep-sea cores, 20 of which are accelerator mass spectrometry (AMS)-14C dated and 30 of which have high (>8 cm/kyr) sedimentation rates, enabling a resolution of about 120 years. Paleotemperature estimates are based on species counts of planktonic foraminifera in 18 cores. The •5180 and •513C distributions depict three main modes of surface circulation: (1) The Holocene-style interglacial mode which largely persisted over the last 12.8 •4C ka, and probably during large parts of stage 3. (2) The peak glacial mode showing a cyclonic gyre in the, at least, seasonally ice-free Nordic Seas and a meltwater lens west of Ireland. Based on geostrophic forcing, it possibly turned clockwise, blocked the S-N flow across the eastern Iceland-Shetland ridge, and enhanced the Irminger current around west Iceland. It remains unclear whether surface-water density was sufficient for deepwater formation west of Norway. (3) A meltwater regime culminating during early glacial Termination I, when a great meltwater lens off northern Norway probably induced a clockwise circulation reaching south up to Faeroe, the northward inflow of Irminger Current water dominated the Icelandic Sea, and deepwater convection was stopped. In contrast to circulation modes two and three, the Holocene-style circulation mode appears most stable, even unaffected by major meltwater pools originating from the Scandinavian ice sheet, such as during •80 event 3.1 and the B611ing. Meltwater phases markedly influenced the European continental climate by suppressing the "heat pump" of the Atlantic salinity conveyor belt. During the peak glacial, melting icebergs blocked the eastward advection of warm surface water toward Great Britain, thus accelerating buildup of the great European ice sheets; in the early deglacial, meltwater probably induced a southward flow of cold water along Norway, which led to the Oldest Dryas cold spell.

Published
1995
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19. The timing of deglacial circulation changes in the Atlantic

Author

Waelbroeck, C., Skinner, Luke C., Labeyrie, Laurent, Duplessy, Jean-Claude, Michel, Elisabeth, Vázquez Riveiros, Natalia, Gherardi, Jeanne, Dewilde, Fabien, Paléocéanographie (PALEOCEAN), Laboratoire des Sciences du Climat et de l'Environnement [Gif-sur-Yvette] (LSCE), Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ), University of Cambridge [UK] (CAM), Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ), Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS), and Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS)

Subjects
[SDU.OCEAN]Sciences of the Universe [physics]/Ocean, Atmosphere, ocean circulation, last deglaciation, [SDU.ENVI]Sciences of the Universe [physics]/Continental interfaces, environment, Atlantic Ocean, ComputingMilieux_MISCELLANEOUS, benthic oxygen isotope
Abstract

Well-dated benthic foraminifer oxygen isotopic records (delta O-18) from different water depths and locations within the Atlantic Ocean exhibit distinct patterns and significant differences in timing over the last deglaciation. This has two implications: on the one hand, it confirms that benthic delta O-18 cannot be used as a global correlation tool with millennial-scale precision, but on the other hand, the combination of benthic isotopic records with independent dating provides a wealth of information on past circulation changes. Comparing new South Atlantic benthic isotopic data with published benthic isotopic records, we show that (1) circulation changes first affected benthic delta O-18 in the 1000-2200 m range, with marked decreases in benthic delta O-18 taking place at similar to 17.5 cal. kyr B.P. (ka) due to the southward propagation of brine waters generated in the Nordic Seas during Heinrich Stadial 1 (HS1) cold period; (2) the arrival of delta O-18-depleted deglacial meltwater took place later at deeper North Atlantic sites; (3) hydrographic changes recorded in North Atlantic cores below 3000 m during HS1 do not correspond to simple alternations between northern-and southern-sourced water but likely reflect instead the incursion of brine-generated deep water of northern as well as southern origin; and (4) South Atlantic waters at similar to 44 degrees S and similar to 3800 m depth remained isolated from better-ventilated northern-sourced water masses until after the resumption of North Atlantic Deep Water (NADW) formation at the onset of the Bolling-Allerod, which led to the propagation of NADW into the South Atlantic.

Published
2011
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21. Variações da produtividade oceânica ao largo da Península Ibérica durante o MIS 5 e a sua relação com a Circulação Thermohalina = Open ocean productivity changes off Iberia during MIS 5 and its relation to the Atlantic Meridional Overturning Circulation

Author

Nave, Silvia, Lebreiro, Susana, Kissel, Catherine, Guihou, Abel, Figueiredo, M. Ondina, Silva, Teresa, Michel, Elizabeth, Cortijo, Elisa, Labeyrie, Laurent, and Voelker, Antje H. L.

Subjects
Granulometria, Corrente marinha, Foraminíferos bentónicos, Oceanografia, Geologia marinha, Circulação oceânica, Nutrientes
Abstract

O estudo mostrou que a produtividade oceânica ao largo da costa ocidental Portuguesa é maior durante as fases frias do Estádio 5 e durante os Estádios Glaciares 4 e 6, sugerindo uma maior disponibilidade de nutrientes durante esses períodos. Os dados de d13C, variações da granulometria e parâmetros magnéticos, sugerem correntes de fundo mais fortes durante os períodos frios, concordantes com uma maior contribuição das correntes de fundo austrais na margem Este do Atlântico Norte. Os nossos dados sugerem uma ligação entre a variação da produtividade oceânica e a circulação termohalina.

Published
2010

23. Evidence for northward expansion of Antarctic Bottom Water mass in the Southern Ocean during the last glacial inception

Author

Govin, Aline, Michel, Elisabeth, Labeyrie, Laurent, Waelbroeck, Claire, Dewilde, Fabien, Jansen, Eystein, Laboratoire des Sciences du Climat et de l'Environnement [Gif-sur-Yvette] (LSCE), Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ), Climat et Magnétisme (CLIMAG), Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ), Paléocéanographie (PALEOCEAN), Bjerknes Centre for Climate Research (BCCR), Department of Biological Sciences [Bergen] (BIO / UiB), University of Bergen (UiB)-University of Bergen (UiB), Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS), and Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS)

Subjects
climate variability, interglacial period, deep ocean, sea, [SDU.STU.CL]Sciences of the Universe [physics]/Earth Sciences/Climatology, Atlantic, hemisphere, circulation, temperature, isotope substage 5E, ice core, ComputingMilieux_MISCELLANEOUS
Abstract

We investigated deep water changes in the Southern Ocean during the last glacial inception, in relationship to surface hydrology and global climatology, to better understand the mechanisms of the establishment of a glacial ocean circulation. Changes in benthic foraminiferal delta(13)C from three high-resolution cores are compared and indicate decoupled intermediate and deep water changes in the Southern Ocean. From the comparison with records from the North Atlantic, South Atlantic, and the Southern Ocean, we show that the early southern deep water delta(13)C drop observed at the MIS 5.5-5.4 transition occurred before any significant reduction of North Atlantic Deep Water ventilation. We propose that this drop is linked to the northward expansion of poorly ventilated Antarctic Bottom Water (AABW) mass in the Southern Ocean. Associated with an early cooling in the high southern latitudes, the westerly winds and surface oceanic fronts would migrate equatorward, thus weakening the upwelling of Circumpolar Deep Waters. Reduced heat brought to Antarctic surface waters would enhance sea ice formation during winters and the deep convection of cold and poorly ventilated AABW.

Published
2009
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24. Constraints on the magnitude and patterns of ocean cooling at the Last Glacial Maximum

Author

Waelbroeck, C., Paul, A., Kucera, Michal, Rosell-Melé, Antoni, Weinelt, Mara, Schneider, Ralph, Mix, Alan C., Abelmann, Andrea, Armand, Leanne, Bard, Edouard, Barker, Stephen, Barrows, Timothy T., Benway, H., Cacho, Isabel, Chen, Min-Te, Cortijo, Elsa, Crosta, X., de Vernal, Anne, Dokken, Trond, Duprat, Josette, Elderfield, Harry, Eynaud, Frédérique, Gersonde, Rainer, Hayes, Angela, Henry, M., Hillaire-Marcel, Claude, Huang, C.-C., Jansen, Eystein, Juggins, Stephen, Kallel, N., Kiefer, Thorsten, Kienast, M., Labeyrie, Laurent, Leclaire, H., Londeix, L., Mangin, S., Matthiessen, Jens, Marret, F., Meland, M., Morey, Ann E., Mulitza, Stefan, Pflaumann, Uwe, Pisias, N. G., Radi, T., Rochon, A., Rohling, Eelco J., Sbaffi, Laura, Schaefer-Neth, C., Solignac, Sandrine, Spero, Howard J., Kazuyo, Tachikawa, Turon, J.-L., Members, Margo Project, Laboratoire des Sciences du Climat et de l'Environnement [Gif-sur-Yvette] (LSCE), Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS), Paléocéanographie (PALEOCEAN), Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS), Department of Geosciences, Institute of Geosciences, Eberhard Karls Universität Tübingen = Eberhard Karls University of Tuebingen, Institute of Environmental Science and Technology [Barcelona] (ICTA), Universitat Autònoma de Barcelona (UAB), Institució Catalana de Recerca i Estudis Avançats (ICREA), Service de Chimie Inorganique et Biologique (SCIB - UMR E3), Institut Nanosciences et Cryogénie (INAC), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Grenoble Alpes [2016-2019] (UGA [2016-2019])-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Grenoble Alpes [2016-2019] (UGA [2016-2019])-Centre National de la Recherche Scientifique (CNRS), Collège de France - Chaire Evolution du climat et de l'océan, Centre européen de recherche et d'enseignement des géosciences de l'environnement (CEREGE), Institut de Recherche pour le Développement (IRD)-Aix Marseille Université (AMU)-Collège de France (CdF (institution))-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Institut National de Recherche pour l’Agriculture, l’Alimentation et l’Environnement (INRAE)-Institut de Recherche pour le Développement (IRD)-Aix Marseille Université (AMU)-Collège de France (CdF (institution))-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Institut National de Recherche pour l’Agriculture, l’Alimentation et l’Environnement (INRAE), Department of Stratigraphy Paleontology and Marine Geosciences, University of Barcelona, Environnements et Paléoenvironnements OCéaniques (EPOC), Observatoire aquitain des sciences de l'univers (OASU), Université Sciences et Technologies - Bordeaux 1 (UB)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Université Sciences et Technologies - Bordeaux 1 (UB)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-École Pratique des Hautes Études (EPHE), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Centre National de la Recherche Scientifique (CNRS), Bjerknes Centre for Climate Research (BCCR), Department of Biological Sciences [Bergen] (BIO / UiB), University of Bergen (UiB)-University of Bergen (UiB), Centre de Spectrométrie Nucléaire et de Spectrométrie de Masse (CSNSM), Université Paris-Sud - Paris 11 (UP11)-Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Centre National de la Recherche Scientifique (CNRS), Department of Bentho-pelagic processes, Alfred-Wegener-Institut, Helmholtz-Zentrum für Polar- und Meeresforschung (AWI), Division of Geological and Planetary Sciences [Pasadena], California Institute of Technology (CALTECH), Centre de recherche sur la dynamique du système Terre (GEOTOP), École Polytechnique de Montréal (EPM)-McGill University = Université McGill [Montréal, Canada]-Université de Montréal (UdeM)-Université du Québec en Abitibi-Témiscamingue (UQAT)-Université du Québec à Rimouski (UQAR)-Concordia University [Montreal]-Université du Québec à Montréal = University of Québec in Montréal (UQAM), Unité GEOGLOB, Faculté des Sciences de Sfax, Université de Sfax - University of Sfax-Université de Sfax - University of Sfax, Past Global Changes International Project Office (PAGES), Past Global Changes International Project Office, Centre d'Études Biologiques de Chizé (CEBC), Centre National de la Recherche Scientifique (CNRS), School of Environmental Sciences, University of Liverpool, Center for Marine Environmental Sciences [Bremen] (MARUM), Universität Bremen, National Oceanography Centre [Southampton] (NOC), University of Southampton, Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ), Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ), Chaire Evolution du climat et de l'océan, Université Sciences et Technologies - Bordeaux 1-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Université Sciences et Technologies - Bordeaux 1-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-École pratique des hautes études (EPHE), Centre National de la Recherche Scientifique (CNRS)-Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Université Paris-Sud - Paris 11 (UP11), Université de Montréal (UdeM)-McGill University = Université McGill [Montréal, Canada]-École Polytechnique de Montréal (EPM)-Concordia University [Montreal]-Université du Québec à Rimouski (UQAR)-Université du Québec à Montréal = University of Québec in Montréal (UQAM)-Université du Québec en Abitibi-Témiscamingue (UQAT), Centre d'études biologiques de Chizé (CEBC), Université Paris-Saclay-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Centre National de la Recherche Scientifique (CNRS), Institut Pierre-Simon-Laplace (IPSL), École normale supérieure - Paris (ENS Paris)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Université Pierre et Marie Curie - Paris 6 (UPMC)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Centre National d'Études Spatiales [Toulouse] (CNES)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-École polytechnique (X), Eberhard Karls Universität Tübingen, Universitat Autònoma de Barcelona [Barcelona] (UAB), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Grenoble Alpes (UGA)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Grenoble Alpes (UGA)-Centre National de la Recherche Scientifique (CNRS), Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche pour le Développement (IRD)-Collège de France (CdF)-Institut national des sciences de l'Univers (INSU - CNRS)-Aix Marseille Université (AMU)-Institut National de la Recherche Agronomique (INRA), Université Sciences et Technologies - Bordeaux 1-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Université Sciences et Technologies - Bordeaux 1-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-École pratique des hautes études (EPHE)-Centre National de la Recherche Scientifique (CNRS), University of Bergen (UIB), École Polytechnique de Montréal (EPM)-Université McGill -Université de Montréal (UdeM)-Université du Québec en Abitibi-Témiscamingue (UQAT)-Université du Québec à Rimouski (UQAR)-Concordia University [Montreal]-Université du Québec à Montréal (UQAM), PAGES International Project Office, Zähringerstrasse 25, 3122 Bern, Switzerland, Univsersity of Liverpool, Laboratoire des Sciences du Climat et de l'Environnement [Gif-sur-Yvette] ( LSCE ), Université de Versailles Saint-Quentin-en-Yvelines ( UVSQ ) -Commissariat à l'énergie atomique et aux énergies alternatives ( CEA ) -Université Paris-Saclay-Centre National de la Recherche Scientifique ( CNRS ), Institut Pierre-Simon-Laplace ( IPSL ), École normale supérieure - Paris ( ENS Paris ) -Université de Versailles Saint-Quentin-en-Yvelines ( UVSQ ) -Université Pierre et Marie Curie - Paris 6 ( UPMC ) -Commissariat à l'énergie atomique et aux énergies alternatives ( CEA ) -Centre National d'Etudes Spatiales ( CNES ) -Institut national des sciences de l'Univers ( INSU - CNRS ) -Centre National de la Recherche Scientifique ( CNRS ), Inst. of Environmental Science and Technology (ICTA), Institució Catalana de Recerca i Estudis Avançats, Institució Catalana de Recerca i Estudis Avançats ( ICREA ), Service de Chimie Inorganique et Biologique ( SCIB - UMR E3 ), Institut Nanosciences et Cryogénie ( INAC ), Commissariat à l'énergie atomique et aux énergies alternatives ( CEA ) -Université Grenoble Alpes ( UGA ) -Commissariat à l'énergie atomique et aux énergies alternatives ( CEA ) -Université Grenoble Alpes ( UGA ) -Centre National de la Recherche Scientifique ( CNRS ), Centre européen de recherche et d'enseignement de géosciences de l'environnement ( CEREGE ), Centre National de la Recherche Scientifique ( CNRS ) -Institut de Recherche pour le Développement ( IRD ) -Aix Marseille Université ( AMU ) -Collège de France ( CdF ) -Institut National de la Recherche Agronomique ( INRA ) -Institut national des sciences de l'Univers ( INSU - CNRS ), Environnements et Paléoenvironnements OCéaniques ( EPOC ), Observatoire aquitain des sciences de l'univers ( OASU ), Université Sciences et Technologies - Bordeaux 1-Institut national des sciences de l'Univers ( INSU - CNRS ) -Centre National de la Recherche Scientifique ( CNRS ) -Université Sciences et Technologies - Bordeaux 1-Institut national des sciences de l'Univers ( INSU - CNRS ) -Centre National de la Recherche Scientifique ( CNRS ) -École pratique des hautes études ( EPHE ) -Centre National de la Recherche Scientifique ( CNRS ), Bjerknes Centre for Climate Research ( BCCR ), University of Bergen ( UIB ), Centre de Spectrométrie Nucléaire et de Spectrométrie de Masse ( CSNSM ), Université Paris-Sud - Paris 11 ( UP11 ) -Institut National de Physique Nucléaire et de Physique des Particules du CNRS ( IN2P3 ) -Centre National de la Recherche Scientifique ( CNRS ), Alfred Wegener Institute, Helmholtz Centre for Polar and Marine Research ( AWI ), California Institute of Technology ( CALTECH ), GEOTOP-UQAM-McGill, Faculté des sciences de Sfax, Centre d'études biologiques de Chizé ( CEBC ), Centre National de la Recherche Scientifique ( CNRS ), MARUM &ndash, Center For Marine Environmental Sciences, National Oceanography Centre [Southampton] ( NOC ), and University of Southampton [Southampton]

Subjects
[SDU.OCEAN]Sciences of the Universe [physics]/Ocean, Atmosphere, geography, geography.geographical_feature_category, 010504 meteorology & atmospheric sciences, [SDU.ASTR]Sciences of the Universe [physics]/Astrophysics [astro-ph], Climate change, Last Glacial Maximum, 010502 geochemistry & geophysics, 01 natural sciences, Sea surface temperature, [SDU.STU.CL]Sciences of the Universe [physics]/Earth Sciences/Climatology, 13. Climate action, Climatology, Paleoclimate Modelling Intercomparison Project, Deglaciation, General Earth and Planetary Sciences, Climate sensitivity, 14. Life underwater, Glacial period, Oceanic basin, [ SDU.ASTR ] Sciences of the Universe [physics]/Astrophysics [astro-ph], [SDU.STU.OC]Sciences of the Universe [physics]/Earth Sciences/Oceanography, Geology, 0105 earth and related environmental sciences
Abstract

International audience; Observation-based reconstructions of sea surface temperature from relatively stable periods in the past, such as the Last Glacial Maximum, represent an important means of constraining climate sensitivity and evaluating model simulations 1. The first quantitative global reconstruction of sea surface temperatures during the Last Glacial Maximum was developed by the Climate Long-Range Investigation, Mapping and Prediction (CLIMAP) project in the 1970s and 1980s (refs 2,3). Since that time, several shortcomings of that earlier effort have become apparent 4. Here we present an updated synthesis of sea surface temperatures during the Last Glacial Maximum, rigorously defined as the period between 23 and 19 thousand years before present, from the Multiproxy Approach for the Reconstruction of the Glacial Ocean Surface (MARGO) project 5. We integrate microfossil and geochemical reconstructions of surface temperatures and include assessments of the reliability of individual records. Our reconstruction reveals the presence of large longitudinal gradients in sea surface temperature in all of the ocean basins, in contrast to the simulations of the Last Glacial Maximum climate available at present 6,7. Studies following the Climate Long-Range Investigation, Mapping and Prediction (CLIMAP) project mainly reanalysed old primary data, applied single new proxies or concentrated on specific ocean basins 8-11. The Multiproxy Approach for the Reconstruction of the Glacial Ocean Surface (MARGO) project's objective has been to compile and analyse available estimates of Last Glacial Maximum (LGM) sea surface temperatures (SSTs) based on all prevalent microfossil-based (transfer functions based on planktonic foraminifera, diatom, dinoflagellate cyst and radiolarian abundances) and geochemical (alkenones and planktonic foraminifera Mg/Ca) palaeothermometers. The MARGO project approach is to argue that no current proxy method is objectively better than another to provide an accurate picture of past SST, and that consequently the multiproxy approach yields the least biased representation of past reality. By using a rigorous definition of the LGM time interval (19-23 cal kyr bp; ref. 4), many records used previously had to be discarded. Other key features are the use of a common data set of ambient temperatures for the calibration of all proxies and the assessment of the reliability of individual SST estimates 5. The MARGO compilation combines 696 individual SST reconstructions (Fig.

Published
2009
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25. Mg/Ca and Sr/Ca ratios in planktonic foraminifera: Proxies for upper water column temperature reconstruction

Author

Cléroux, Caroline, Cortijo, Elsa, Anand, Pallavi, Labeyrie, Laurent, Bassinot, Franck, Caillon, Nicolas, Duplessy, Jean-Claude, Laboratoire des Sciences du Climat et de l'Environnement [Gif-sur-Yvette] (LSCE), Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ), Paléocéanographie (PALEOCEAN), Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ), The Open University [Milton Keynes] (OU), Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS), and Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS)

Subjects
[SDU.OCEAN]Sciences of the Universe [physics]/Ocean, Atmosphere, [SDU.ENVI]Sciences of the Universe [physics]/Continental interfaces, environment
Abstract

International audience; [1] Reliable temperature estimates from both surface and subsurface ocean waters are needed to reconstruct past upper water column temperature gradients and past oceanic heat content. This work examines the relationships between trace element ratios in fossil shells and seawater temperature for surface-dwelling foraminifera species, Globigerinoides ruber (white) and Globigerina bulloides, and deep-dwelling species, Globorotalia inflata, Globorotalia truncatulinoides (dextral and sinistral) and Pulleniatina obliquiloculata. Mg/Ca and Sr/Ca ratios in shells picked in 29 modern core tops from the North Atlantic Ocean are calibrated using calculated isotopic temperatures. Mg/Ca ratios on G. ruber and G. bulloides agree with published data and relationships. For deep-dwelling species, Mg/Ca calibration follows the equation Mg/Ca = 0.78 (±0.04) Â exp (0.051 (±0.003) Â T) with a significant correlation coefficient of R 2 = 0.74. Moreover, there is no significant difference between the different deep-dwellers analyzed. For the Sr/Ca ratio, the surface dwellers and P. obliquiloculata do not record any temperature dependence. For the Globorotalia species, the thermo dependence of Sr/Ca ratio can be described by a single linear relationship: Sr/Ca = (0.0182 (±0.001) Â T) + 1.097 (±0.018), R 2 = 0.85. Temperature estimates with a 1 sigma error of ±2.0°C and ±1.3°C can be derived from the Mg/Ca and Sr/Ca ratios, respectively, as long as the Sr geochemistry in the ocean has been constant through time. Citation: Cléroux, C., E. Cortijo, P. Anand, L. Labeyrie, F. Bassinot, N. Caillon, and J.-C. Duplessy (2008), Mg/Ca and Sr/Ca ratios in planktonic foraminifera: Proxies for upper water column temperature reconstruction, Paleoceanography, 23, PA3214

Published
2008
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26. Low-latitude hydrological cycle and rapid climate changes during the last deglaciation

Author

Levi, Camille, Labeyrie, Laurent, Bassinot, Franck, Guichard, Francois, Cortijo, Elsa, Waelbroeck, Claire, Caillon, Nicolas, Duprat, Josette, De Garidel-thoron, Thibault, Elderfield, Harry, Laboratoire des Sciences du Climat et de l'Environnement [Gif-sur-Yvette] (LSCE), Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ), Paléocéanographie (PALEOCEAN), Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ), Environnements et Paléoenvironnements OCéaniques (EPOC), Observatoire aquitain des sciences de l'univers (OASU), Université Sciences et Technologies - Bordeaux 1-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Université Sciences et Technologies - Bordeaux 1-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-École pratique des hautes études (EPHE), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Centre National de la Recherche Scientifique (CNRS), Centre européen de recherche et d'enseignement des géosciences de l'environnement (CEREGE), Aix Marseille Université (AMU)-Institut national des sciences de l'Univers (INSU - CNRS)-Collège de France (CdF (institution))-Institut de Recherche pour le Développement (IRD)-Centre National de la Recherche Scientifique (CNRS)-Institut National de la Recherche Agronomique (INRA), Department of Earth Sciences [Cambridge, UK], University of Cambridge [UK] (CAM), Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS), Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS), Université Sciences et Technologies - Bordeaux 1 (UB)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Université Sciences et Technologies - Bordeaux 1 (UB)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-École Pratique des Hautes Études (EPHE), Institut de Recherche pour le Développement (IRD)-Institut National de la Recherche Agronomique (INRA)-Aix Marseille Université (AMU)-Collège de France (CdF (institution))-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS), Université Paris-Saclay-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Centre National de la Recherche Scientifique (CNRS), Université Sciences et Technologies - Bordeaux 1-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Université Sciences et Technologies - Bordeaux 1-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-École pratique des hautes études (EPHE)-Centre National de la Recherche Scientifique (CNRS), and Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche pour le Développement (IRD)-Collège de France (CdF)-Institut national des sciences de l'Univers (INSU - CNRS)-Aix Marseille Université (AMU)-Institut National de la Recherche Agronomique (INRA)

Subjects
paleoceanography : El Nino, rapid climate changes, [SDU.STU.CL]Sciences of the Universe [physics]/Earth Sciences/Climatology, [SDE.MCG]Environmental Sciences/Global Changes, global change : abrupt/rapid climate change, paleoceanography : general or miscellaneous, last deglaciation, low-latitude hydrological cycle
Abstract

International audience; Sea surface temperature and oxygen isotopic records from two well-dated Indian Ocean cores covering the last deglaciation show the occurrence of two periods of increased salinity along the route of warm surface water transport from the Indian to the Atlantic Ocean, one between 18 and 14.5 ka and the other during the Younger Dryas. Our results imply that during these periods, salt accumulated in the tropical Atlantic, creating favorable conditions for an abrupt resumption of the thermohaline circulation and abrupt northern hemisphere warming. Furthermore, we suggest that the observed pattern of millennial climate variability during the last glacial and deglaciation resulted from the interaction between the relatively slow rhythm of expansion and decay of the northern hemisphere ice sheets, and El Nino-Southern Oscillation variability, through changes in the position of the Intertropical Convergence Zone. This interaction generated an oscillator with millennial time response that operated at times of sufficient northern hemisphere ice sheets extent.

Published
2007
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27. A 27 kyr terrestrial biomarker record in the southern Indian Ocean

Author

Sicre, Marie-Alexandrine, Labeyrie, Laurent, Ezat, Ullah, Mazaud, Alain, Turon, Jean-Louis, Laboratoire des Sciences du Climat et de l'Environnement [Gif-sur-Yvette] (LSCE), Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ), Paléocéanographie (PALEOCEAN), Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ), Climat et Magnétisme (CLIMAG), UMR 5805 Environnements et Paléoenvironnements Océaniques et Continentaux (EPOC), Observatoire aquitain des sciences de l'univers (OASU), Université Sciences et Technologies - Bordeaux 1-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Université Sciences et Technologies - Bordeaux 1-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-École pratique des hautes études (EPHE), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Centre National de la Recherche Scientifique (CNRS), Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS), Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS), Environnements et Paléoenvironnements OCéaniques (EPOC), and Université Sciences et Technologies - Bordeaux 1 (UB)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Université Sciences et Technologies - Bordeaux 1 (UB)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-École Pratique des Hautes Études (EPHE)

Subjects
4926 Paleoceanography: Glacial, [SDU.OCEAN]Sciences of the Universe [physics]/Ocean, Atmosphere, glacial, terrestrial Index Terms: 3344 Atmospheric Processes: Paleoclimatology (0473, terrestrial, paleoclimate, 4924 Paleoceanography: Geochemical tracers, biomarker, [SDU.ENVI]Sciences of the Universe [physics]/Continental interfaces, environment, Indian Ocean, marine sediments, 4900)
Abstract

International audience; [1] Terrestrial inputs were reconstructed using high molecular weight n-alkane concentrations recorded in the sub-Antarctic Indian Ocean core MD94-103 (45°35 0 S, 86°31 0 E, 3560 m) to examine regional changes in the atmospheric circulation over the last 27 kyr. This record was compared to the dust content of EPICA-Dome C ice and continental data from South Africa (e.g., pollen sequences and isotope records in speleothems) to get a comprehensive understanding of atmospheric links between low and midlatitudes of the Indian Ocean. Terrestrial n-alkanes indicate higher glacial than Holocene inputs and marked glacial oscillations. Minimum values during the Last Glacial Maximum (LGM) are consistent with colder and drier climate and presumably caused by the persistence of subtropical anticyclones over southern Africa limiting the amount of rainfall and vegetation growth. The otherwise higher glacial n-alkanes suggest a stronger influence of the tropical rainfall in southern Africa, likely associated with a contraction of the polar vortex with respect to its LGM position. During northern Heinrich events, moderate decline of n-alkanes suggests reduced rainfall over southern Africa possibly caused by weaker tropical easterly winds when, according to Stott et al. (2002), the Pacific Ocean would have experienced Super-ENSO conditions. Components: 5185 words, 3 figures.

Published
2006
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28. Oversampling of sedimentary series collected by giant piston corer: Evidence and corrections based on 3.5-kHz chirp profiles

Author

Széréméta, Nadia, Bassinot, Franck, Balut, Yvon, Labeyrie, Laurent, Pagel, Maurice, Laboratoire des Sciences du Climat et de l'Environnement [Gif-sur-Yvette] (LSCE), Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS), Climat et Magnétisme (CLIMAG), Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS), Paléocéanographie (PALEOCEAN), L'Institut polaire français Paul-Emile Victor (IPEV), Ministère de l'Education nationale, de l’Enseignement supérieur et de la Recherche (M.E.N.E.S.R.), Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ), and Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)

Subjects
[SDU.OCEAN]Sciences of the Universe [physics]/Ocean, Atmosphere, giant piston coring, L Labeyrie, 4259 Oceanography: General: Ocean acoustics, F Bassinot, North Atlantic, IMAGES cores, and M Pagel (2004), KEYWORDS: correction of coring-induced sediment oversampling, INDEX TERMS: 1635 Global Change: Oceans (4203), 4294 Oceanography: General: Instruments and techniques, Y Balut, correction of coring-induced sediment oversampling, [SDU.ENVI]Sciences of the Universe [physics]/Continental interfaces, environment, North Atlantic Citation: Széréméta
Abstract

International audience; [1] The depth-scale accuracy of marine sedimentary series collected by coring is of key importance for the precise calculation of sedimentation rates and fluxes. For three giant piston cores collected during the InterPole MD99-114/International Marine Past Global Changes Study (IMAGES) V cruise (MD99-2227, MD99-2246, and MD99-2251), the 3.5-kHz chirp profiles recorded on board are compared to synthetic seismograms computed from physical property logs measured on cores. In each case, the perfect match of main deep reflectors requires a significant upward shift of the water-sediment (W/S) interface in the synthetic seismograms with respect to the 3.5-kHz profiles. Since no drastic perturbation of the physical property logs is observed, this upward shift is interpreted as resulting from a significant sediment oversampling in the upper part of the cores. The affected depth intervals are consistent with the thickness of the perturbed zones observed in penetrometry and anisotropy of magnetic susceptibility records ($10-15 m). To retrieve the true in situ sediment thickness, a linear depth correction is applied between consecutive acoustic reflectors to achieve a perfect match between the synthetic seismogram and the corresponding 3.5-kHz profiles. Depth correction laws (amount of material excess as a function of initial depth) are deduced from this resynchronization procedure. First estimations of upper core oversampling rates range from 30% (core MD99-2227) to 37% (core MD99-2246). Moreover, we observe that some undersampling may also exist in the lower part of the sediment cores.

Published
2004
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30. Mg/Ca-paleothermometry in the western Mediterranean Sea on planktonic foraminifer species Globigerina bulloides: Constraints and implications

Author

Boussetta, Soumaya, Kallel, Nejib, Bassinot, Franck, Labeyrie, Laurent, Duplessy, Jean-claude, Caillon, Nicolas, Dewilde, Fabien, Rebaubier, Helene, Boussetta, Soumaya, Kallel, Nejib, Bassinot, Franck, Labeyrie, Laurent, Duplessy, Jean-claude, Caillon, Nicolas, Dewilde, Fabien, and Rebaubier, Helene

Abstract

We generated a high-resolution SSTMg/Ca record for the surface-dwelling planktonic foraminifera Globigerina bulloides from the core MD99-2346 collected in the Gulf of Lion, and compared it to that obtained using modern analogue techniques applied to fossil foraminiferal assemblages (SSTMAT). The two temperature records display similar patterns during the last 28,000 years but the SSTMg/Ca estimates are several degrees warmer (similar to+4 degrees C) than SSTMAT. The temperature shift between SSTMg/Ca and SSTMAT remained relatively constant over time. This seems to exclude a bias on the Mg/Ca record associated with salinity or secondary Mg-rich calcite encrustation on the foraminiferal tests during early diagenesis. Therefore, anomalously high Mg/Ca suggests either: (1) the empirical equation for G. bulloides of Elderfield and Ganssen (2000) is incorrect; or (2) there is a specific Mediterranean genotypes of G. bulloides for which a specific Mg/Ca-temperature calibration is needed. (c) 2012 Academie des sciences. Published by Elsevier Masson SAS. All rights reserved.

Published
2012
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31. Les soubresauts millénaires du climat

Author

Labeyrie, Laurent, Jouzel, Jean, Laboratoire des Sciences du Climat et de l'Environnement [Gif-sur-Yvette] (LSCE), Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS), Paléocéanographie (PALEOCEAN), Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS), Glaces et Continents, Climats et Isotopes Stables (GLACCIOS), Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ), and Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)

Subjects
[SDU.OCEAN]Sciences of the Universe [physics]/Ocean, Atmosphere, [SDU.ENVI]Sciences of the Universe [physics]/Continental interfaces, environment, ComputingMilieux_MISCELLANEOUS
Abstract

International audience

Published
1999

32. Interlaboratory comparison study of calibration standards for foraminiferal Mg/Ca thermometry

Author

Greaves, M, Caillon, N., Rebaubier, H., Bartoli, G., Bohaty, S, Cacho, I, Clarke, L, Cooper, M, Daunt, C, Delaney, M, deMenocal, P.B., Dutton, Andrea, Eggins, Stephen, Elderfield, H, Garbe-Schoenberg, D., Goddard, E., Green, D., Groeneveld, J., Hastings, D., Hathorne, E, Kimoto, K, Klinkhammer, G, Labeyrie, Laurent, Lea, David W, Marchitto, T, Martinez-Boti, M A, Mortyn, P Graham, Ni, Y, Nuernberg, D., Paradis, G, Pena, L, Quinn, Terrence, Rosenthal, Y, Russell, Ann, Sagawa, T, Sosdian, Sindia, Stott, L, Tachikawa, K, Tappa, E., Thunell, R, Wilson, P.A., Greaves, M, Caillon, N., Rebaubier, H., Bartoli, G., Bohaty, S, Cacho, I, Clarke, L, Cooper, M, Daunt, C, Delaney, M, deMenocal, P.B., Dutton, Andrea, Eggins, Stephen, Elderfield, H, Garbe-Schoenberg, D., Goddard, E., Green, D., Groeneveld, J., Hastings, D., Hathorne, E, Kimoto, K, Klinkhammer, G, Labeyrie, Laurent, Lea, David W, Marchitto, T, Martinez-Boti, M A, Mortyn, P Graham, Ni, Y, Nuernberg, D., Paradis, G, Pena, L, Quinn, Terrence, Rosenthal, Y, Russell, Ann, Sagawa, T, Sosdian, Sindia, Stott, L, Tachikawa, K, Tappa, E., Thunell, R, and Wilson, P.A.

Abstract

An interlaboratory study of Mg/Ca and Sr/Ca ratios in three commercially available carbonate reference materials (BAM RS3, CMSI 1767, and ECRM 752-1) was performed with the participation of 25 laboratories that determine foraminiferal Mg/Ca ratios worldwide. These reference materials containing Mg/Ca in the range of foraminiferal calcite (0.8 mmol/mol to 6 mmol/mol) were circulated with dissolution protocol for analysis. Participants were asked to make replicate dissolutions of the powdered samples and to analyze them using the instruments and calibration standards routinely used in their laboratories. Statistical analysis was performed in accordance with the International Standardization Organization standard 5725, which is based on the analysis of variance (ANOVA) technique. Repeatability (RSDr%), an indicator of intralaboratory precision, for Mg/Ca determinations in solutions after centrifuging increased with decreasing Mg/Ca, ranging from 0.78% at Mg/Ca = 5.56 mmol/mol to 1.15% at Mg/Ca = 0.79 mmol/mol. Reproducibility (RSDR;%), an indicator of the interlaboratory method precision, for Mg/Ca determinations in centrifuged solutions was noticeably worse than repeatability, ranging from 4.5% at Mg/Ca = 5.56 mmol/mol to 8.7% at Mg/Ca = 0.79 mmol/mol. Results of this study show that interlaboratory variability is dominated by inconsistencies among instrument calibrations and highlight the need to improve interlaboratory compatibility. Additionally, the study confirmed the suitability of these solid standards as reference materials for foraminiferal Mg/Ca (and Sr/Ca) determinations, provided that appropriate procedures are adopted to minimize and to monitor possible contamination from silicate mineral phases.

Published
2008

33. Hydrologie et géochimie isotopique

Author

Duplessy, Jean-Claude, Arnold, Maurice, Bard, Édouard, Cortijo, Elsa, Labeyrie, Laurent, Laj, Carlo, Lehmann, Benoit, Mazaud, Alain, Paterne, Martine, Tisnerat-Laborde, Nadine, Vidal, Laurence, Causse, C. (ed.), Gasse, F. (ed.), Laboratoire des Sciences du Climat et de l'Environnement [Gif-sur-Yvette] (LSCE), Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS), Centre européen de recherche et d'enseignement des géosciences de l'environnement (CEREGE), Institut de Recherche pour le Développement (IRD)-Institut National de la Recherche Agronomique (INRA)-Aix Marseille Université (AMU)-Collège de France (CdF (institution))-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS), Géochrononologie Traceurs Archéométrie (GEOTRAC), Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS), Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ), Aix Marseille Université (AMU)-Institut national des sciences de l'Univers (INSU - CNRS)-Collège de France (CdF (institution))-Institut de Recherche pour le Développement (IRD)-Centre National de la Recherche Scientifique (CNRS)-Institut National de la Recherche Agronomique (INRA), and Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)

Subjects
[SDU.OCEAN]Sciences of the Universe [physics]/Ocean, Atmosphere, paléoclimatologie, QUATERNAIRE, CHAMP MAGNETIQUE, PALEOCLIMAT, datation, paléocéanographie, C 14, DATATION ABSOLUE, carbone 14, [SDU.ENVI]Sciences of the Universe [physics]/Continental interfaces, environment, GEOCHRONOLOGIE
Abstract

International audience; La méthode de datation par le carbone 14 a permis l'établissement d'une échelle chronologique du Quaternaire Supérieur et a contribué à ladécouverte de phénomènes insoupçonnés comme l'existence de variations climatiques abruptes et de grande amplitude pendant la dernière période glaciaire et la déglaciation qui l'a terminée. L'effort continu pour comparer les âges carbone 14 avec les âges calendaires a été maintenant étendu au delà de 30 000 ans, même si le nombre de mesures est encore trop petit pour permettre l'établissement d'une courbe de calibration précise au delà des dix mille dernières années. La comparaison des variations du rapport 14C/12C de l'atmosphère avec celles du champ magnétique terrestre (déduites de l'analyse des carottes de sédiments marins) suggère que les variations de l'activité 14C de l'atmosphère sont dues pour une très large part aux fluctuations de l'intensité du champ magnétique terrestre dans le passé. Plus généralement, ces variations joueraient un rôle majeur dans les variations des teneurs des autres cosmonucléides, comme 1°Be, dans les échantillons naturels.

Published
1998

34. IMAGES - MD 101 à bord du Marion-Dufresne du 29 mai au 11 juillet 1995. A coring cruise of the R/V Marion Dufresne in the North Atlantic Ocean and Norwegian Sea

Author

Bassinot, Franck C and Labeyrie, Laurent D.

Abstract

IMAGES coordinated a first international cruise in June and July 1995 over the North Atlantic and Norwegian sea on board the French RN Mm'ion Dufresne (MD 10 I, Brest - Stornoway (Lewis Island) - St-Pierre - Azores - Marseille). Its main scientific objective was the collection of giant piston cores on rapidly sedimenting drifts and continental margins of the North Atlantic ocean and Norwegian Sea, along the track of the main thermohaline circulation. The cruise crossed the North-East Atlantic margins, the Feni Drift, the Scottish, North Faeroes and Norwegian margins (to nON), the Iceland South-East margins, the Gardar Drift, the NAMOC Channel, the Newfoundland margin, the Bermuda rise, the mid Atlantic ridge, and the Azores and Iberian margins. Additional objectives covered: - the contribution of Mediterranean waters to the North Atlantic intermediate waters, with 5 cores recovered across the slopes of the Iberian margin; - the evolution of the NAMOC channel, in the deep North-West Atlantic basin, in relation to the growths and decays of the Laurentide ice sheet (8 Kullenberg and gravity cores). This was the maiden cruise of the new Mm'ion Dujresne, just 2 weeks out from her Le Havre shipyard. The ship had a very small number of problems, taking into account the number of things which were not ready just a few days before the departure. Two days were lost for engine problems. 70 scientists, students and technicians from 22 institutions (13 countries) participated to at least one of the three legs. 43 cores (mean length over 30 meters) have been retrieved during the cruise, described and measured for magnetic susceptibility, p-wave velocity, y density and spectral light reflectance. The longest core, MD 95-2036 (52.64 m) was retrieved at 4461 m water depth on the Bermuda Rise. It covers about 150 kyr with a sedimentation rate over 30 cm/kyr. The Calypso corer worked properly, once a few problems encountered at the be"innin" of the cruise had been solved (i.e. sliced or imploded PVC liner). This report presents preliminary results, mostly obtained on board: core descriptions, physical properties and micro-paleontological stratigraphy. Color reflectance (between 40° and 55°N) and magnetic susceptibility (between 50° and 700N) have been used for direct tuning of the time scales by cyclo-stratigraphy in the precession and obliquity bands. Ocean-wide correlations have been established over the last 250 kyr.

Published
1996

36. Sea-level and deep water temperature changes derived from benthic foraminifera isotopic records

Author

Waelbroeck, Claire, Labeyrie, Laurent, Michel, E, Duplessy, J., McManus, J, Balbon, E., Labracherie, M, Lambeck, Kurt, Waelbroeck, Claire, Labeyrie, Laurent, Michel, E, Duplessy, J., McManus, J, Balbon, E., Labracherie, M, and Lambeck, Kurt

Abstract

We show that robust regressions can be established between relative sea-level (RSL) data and benthic foraminifera oxygen isotopic ratios from the North Atlantic and Equatorial Pacific Ocean over the last climatic cycle. We then apply these regressions to

Published
2002

37. Paleointensity of the Geomagnetic Field During the Last 80,000 Years

Author

Tric, Emmanuel, Valet, Jean-Pierre, Tucholka, Piotr, Paterne, Martine, Labeyrie, Laurent, Guichard, Francois, Tauxe, Lisa, Fontugne, Michel, Valet, $ean-Pierre, Centre des Faibles Radioactivités, Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Centre National de la Recherche Scientifique (CNRS), Institut de Physique du Globe de Paris (IPGP (UMR_7154)), Institut national des sciences de l'Univers (INSU - CNRS)-Université de La Réunion (UR)-Institut de Physique du Globe de Paris (IPG Paris)-Centre National de la Recherche Scientifique (CNRS)-Université Paris Cité (UPCité), Laboratoire de Géophysique [Orsay], Université Paris-Sud - Paris 11 (UP11), and The Scripps Research Institute [La Jolla, San Diego]

Subjects
Atmospheric Science, Paleomagnetism, Soil Science, Aquatic Science, Oceanography, Isotopes of oxygen, Geochemistry and Petrology, Earth and Planetary Sciences (miscellaneous), [SDU.ENVI]Sciences of the Universe [physics]/Continental interfaces, environment, Earth-Surface Processes, Water Science and Technology, [SDU.OCEAN]Sciences of the Universe [physics]/Ocean, Atmosphere, geography, geography.geographical_feature_category, Ecology, Paleontology, Forestry, Geophysics, Earth's magnetic field, Volcano, Space and Planetary Science, Magnetic mineralogy, Geochronology, Period (geology), Magnetic dipole, Geology
Abstract

International audience; High-resolution records of the relative paleointensity of the geomagnetic field have been obtained from five marine cores. Three duplicate records were used to estimate the regional coherency of the data within a single area (Tyrrhrenian Sea) while the two others document the field variations in the eastern Mediterranean and the southern Indian Ocean. Careful investigations of distinct rock magnetic parameters have established the downcore unifornfity of the sediments in terms of magnetic nfineralogy and grain sizes. The time-depth control was provided by oxygen isotopes, and small-scale variations in the deposition rates were constrained by means of tephrachronology. The synthetic curve calculated from the Mediterranean records provides a continuous record of the intensity variations during the last 80,000 years (80 kyr), which correlates well with the sparse volcanic data available for the period 0-40 kyr. The fact that identical behavior is seen in both data sets and that they also compare quite well with results from a core collected in the Pacific Ocean establishes the truly dipolar character of these variations. The dipole field moment is characterized by large-scale changes as shown by the existence of pronounced drops (at 39 and 60 kyr) alternating with periods of higher intensity. The record suggests a periodic nature for these intensity variations; however, the period studied is not sufficiently long to state this conclusively. These results demonstrate the potential of sediments for such studies and constitute a first step towards obtaining a global paleointensity record over a long period of time.

Published
1992
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38. Hydrological relationship between the North Atlantic Ocean and the Mediterranean Sea during the past 15-75 kyr

Author

Paterne, Martine, Kallel, Nejib, Labeyrie, Laurent, Vautravers, Maryline J., Duplessy, Jean-claude, Rossignol-strick, Martine, Cortijo, Elsa, Arnold, Maurice, Fontugne, Michel, Paterne, Martine, Kallel, Nejib, Labeyrie, Laurent, Vautravers, Maryline J., Duplessy, Jean-claude, Rossignol-strick, Martine, Cortijo, Elsa, Arnold, Maurice, and Fontugne, Michel

Abstract

The Mediterranean Sea hydrology at the time of the Heinrich formation in the North Atlantic Ocean was analyzed by comparing sea surface temperatures (SSTs) and oxygen isotope composition of seawater (delta w) changes during the past 75 kyr in two marine cores. These were compared to the palynological variations derived in the Mediterranean Sea core. During the last glacial the two oceanic SST records show similar and synchronous patterns, with several long-term cooling periods, ending by abrupt SST increases. At the time of the Heinrich events, cold SSTs and low salinity prevailed in the Mediterranean Sea. The freshwater budget was similar to the modern one, permitting the presence of a mixed forest on the Mediterranean borderlands. The post-Heinrich periods are marked by a freshwater budget decrease, limiting oak and fir tree growth in the Mediterranean region. Increase of precipitation or reduction of evaporation is observed before the Heinrich episode, and is associated with a well-developed mixed Mediterranean forest.

Published
1999
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41. correction: The timing of the last deglaciation in North Atlantic climate records

Author

Waelbroeck, Claire, Duplessy, Jean-Claude, Michel, Elisabeth, Labeyrie, Laurent, Paillard, Didier, and Duprat, Josette

Subjects
Environmental issues, Science and technology, Zoology and wildlife conservation
Abstract

Author(s): Claire Waelbroeck; Jean-Claude Duplessy; Elisabeth Michel; Laurent Labeyrie; Didier Paillard; Josette Duprat Nature 412, 724-727 (2001). We directly used the observed leads of sea surface temperature with respect to [...]

Published
2001
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42. erratum: The timing of the last deglaciation in North Atlantic climate records

Author

Waelbroeck, Claire, Duplessy, Jean-Claude, Michel, Elisabeth, Labeyrie, Laurent, Paillard, Didier, and Duprat, Josette

Subjects
Environmental issues, Science and technology, Zoology and wildlife conservation
Abstract

Author(s): Claire Waelbroeck; Jean-Claude Duplessy; Elisabeth Michel; Laurent Labeyrie; Didier Paillard; Josette Duprat Nature, 412, 724-727 (2001). In this Letter, the following line should have appeared before the reference list: [...]

Published
2001
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44. Is there a relationship between atmospheric CO2 and manganese in the Ocean?

Author

Zahn, Rainer, Pederson, T.F., Kannish, M.A, Labeyrie, Laurent, Mangini, A., Rutsch, H.J., Frank, Martin, Eisenhauer, Anton, Eckhardt, J.-D., Zahn, Rainer, Pederson, T.F., Kannish, M.A, Labeyrie, Laurent, Mangini, A., Rutsch, H.J., Frank, Martin, Eisenhauer, Anton, and Eckhardt, J.-D.

Published
1994

45. Coarse fraction fluctuations in pelagic carbonate sediments from the tropical Indian Ocean: A 1500-kyr record of carbonate dissolution

Author

Bassinot, Franck, Beaufort, Luc, Vincent, Edith, Labeyrie, Laurent, Rostek, Frauke, Muller, Pj, Quidelleur, Xavier, Lancelot, Y, Bassinot, Franck, Beaufort, Luc, Vincent, Edith, Labeyrie, Laurent, Rostek, Frauke, Muller, Pj, Quidelleur, Xavier, and Lancelot, Y

Abstract

We examined coarse fraction contents of pelagic carbonates deposited between 2000- and 3700-m water depth in the tropical Indian Ocean using ocean Drilling Program (ODP) sites 722 (Owen Ridge, Arabian Sea) and 758 (Ninetyeast Ridge, eastern equatorial Indian Ocean), and four giant piston cores collected by the French RN Marion Dufresne during the SEYMAMA expedition. Over the last 1500 kyr, coarse fraction records display high-amplitude oscillations with an irregular wavelength on the order of approximately 500 kyr. These oscillations can be correlated throughout the entire equatorial Indian Ocean, from the Seychelles area eastward to the Ninetyeast Ridge, and into the Arabian Sea. Changes in grain size mainly result from changes in carbonate dissolution as evidenced by the positive relationship between coarse fraction content and a foraminiferal preservation index based on test fragmentation. The well-known ''mid-Brunhes dissolution cycle'' represents the last part of this irregular long-term dissolution oscillation. The origin of this long-term oscillation is still poorly understood. Our observations suggest that it is not a true cycle (it has an irregular wavelength) and we propose that it may result from long-term changes in Ca++ flux to the ocean. Sites 722 and 758 deltaO-18 records provide a high-resolution stratigraphy that allows a detailed intersite comparison of the two coarse fraction records over the last 1500 kyr. Site 722 (2030 m) lies above the present and late Pleistocene lysocline. The lysocline shoaled to the position of site 758 (2925 m) only during the interglacial intervals that occurred between about 300 and 500 ka (Peterson and Prell, 1985a). Despite these supralysoclinal positions of the two sites, short-term changes in coarse fraction contents are correlatable from one site to another and probably result from regional (or global) dissolution pulses. By stacking the normalized coarse fraction records from sites 722 and 758, we constructed a Co

Published
1994
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48. Sudden changes in a glacial world

Author

Labeyrie, Laurent, Jouzel, Jean, Lévi, Camille, and Cortijo, Elsa

Abstract

The most characteristic records of the millennial variability of climate during the last glacial period may be separated into two classes of signals: Greenland and Antarctic. The Greenland type is found over the whole North American and Euro-Asian continental blocks. Continental cooling associated with the maximum ice sheet extension, and resulting surges on the marine margins have affected the whole latitude range, with a probable strong albedo feedback due to winter snow cover. At the opposite, the surface temperature of tropical oceans did not change as much, which created large seasonal meandering of the Intertropical Convergence Zone (ITCZ), and facilitated meridional atmospheric vapour transport towards cold continents, and heat transfer in particular to the southern hemisphere. The rapid growth of ice sheets facilitated periodic surges and decreases in meridional overturning circulation. We propose that the major difference in the characteristics of the ‘Greenland’ and ‘Antarctic’ classes of climate variability result mostly from the difference in continent/ocean distribution in both hemispheres. To cite this article: L. Labeyrie et al., C. R. Geoscience 336 (2004). [Copyright &y& Elsevier]

Published
2004
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