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| Royer, Aurelien; Malaize, Bruno; Lecuyer, Christophe; Queffelec, Alain; Charlier, Karine; Caley, Thibaut; Lenoble, Arnaud. |
| In neotropical regions, fossil bat guano accumulated over time as laminated layers in caves, hence providing a high-resolution temporal record of terrestrial environmental changes. Additionally, cave settings have the property to preserve such organic sediments from processes triggered by winds (deflation, abrasion and sandblasting) and intense rainfall (leaching away). This study reports both stable carbon and nitrogen isotope compositions of frugivorous bat guano deposited in a well-preserved stratigraphic succession of Blanchard Cave on Marie-Galante, Guadeloupe. These isotopic data are discussed with regard to climate changes and its specific impact on Eastern Caribbean vegetation during the Late Pleistocene from 40 to 10 ka cal. BP. Guano delta C-13... |
| Tipo: Text |
Palavras-chave: Caribbean Basin; Last Glacial; Guano; Carbon isotope; Nitrogen isotope. |
| Ano: 2017 |
URL: https://archimer.ifremer.fr/doc/00421/53200/54982.pdf |
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| Caley, Thibaut; Extier, Thomas; Collins, James A.; Schefuss, Enno; Dupont, Lydie; Malaize, Bruno; Rossignol, Linda; Souron, Antoine; Mcclymont, Erin L.; Jimenez-espejo, Francisco J.; Garcia-comas, Carmen; Eynaud, Frederique; Martinez, Philippe; Roche, Didier M.; Jorry, Stephan; Charlier, Karine; Wary, Melanie; Gourves, Pierre-yves; Billy, Isabelle; Giraudeau, Jacques. |
| The past two million years of eastern African climate variability is currently poorly constrained, despite interest in understanding its assumed role in early human evolution1,2,3,4. Rare palaeoclimate records from northeastern Africa suggest progressively drier conditions2,5 or a stable hydroclimate6. By contrast, records from Lake Malawi in tropical southeastern Africa reveal a trend of a progressively wetter climate over the past 1.3 million years7,8. The climatic forcings that controlled these past hydrological changes are also a matter of debate. Some studies suggest a dominant local insolation forcing on hydrological changes9,10,11, whereas others infer a potential influence of sea surface temperature changes in the Indian Ocean8,12,13. Here we show... |
| Tipo: Text |
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| Ano: 2018 |
URL: https://archimer.ifremer.fr/doc/00449/56059/57581.pdf |
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| Tisserand, Amandine; Malaize, Bruno; Jullien, Elsa; Zaragosi, Sebastien; Charlier, Karine; Grousset, Francis. |
| A reconstruction of northwest African summer monsoon strength during the cold marine isotopic stage (MIS) 6 indicates a link to the seasonal migration of the Intertropical Convergence Zone (ITCZ). High-resolution studies of eolian dust supply and sea surface temperature recorded in marine core MD03-2705, on the Mauritanian margin, provide a better understanding about the penultimate glacial history of northwestern African aridity/humidity and upwelling coastal activity. Today, site MD03-2705 experiences increased upwelling and dust flux during the winter months, when the ITCZ is in a southerly position. Analyses of foraminifera isotopic composition suggest that during MIS 6.5 (180 - 168 ka) the average position of the ITCZ migrated north, marked by an... |
| Tipo: Text |
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| Ano: 2009 |
URL: https://archimer.ifremer.fr/doc/00218/32937/31444.pdf |
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| Caley, Thibaut; Giraudeau, Jacques; Malaize, Bruno; Rossignol, Linda; Pierre, Catherine. |
| Heat and salt transfer from the Indian Ocean to the Atlantic Ocean (Agulhas leakage) has an important effect on the global thermohaline circulation and climate. The lack of long transfer record prevents elucidation of its role on climate changes throughout the Quaternary. Here, we present a 1,350-ka accumulation rate record of the planktic foraminiferal species Globorotalia menardii. We demonstrate that, according to previous assumptions, the presence and reseeding of this fauna in the subtropical southeast Atlantic was driven by interocean exchange south of Africa. The Agulhas transfer strengthened at glacial ice-volume maxima for every glacial-interglacial transition, with maximum reinforcements organized according to a 400-ka periodicity. The long-term... |
| Tipo: Text |
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| Ano: 2012 |
URL: https://archimer.ifremer.fr/doc/00265/37658/36513.pdf |
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| Castaneda, Isla S.; Caley, Thibaut; Dupont, Lydie; Kim, Jung-hyun; Malaize, Bruno; Schouten, Stefan. |
| In this study we investigate Pleistocene vegetation and climate change in southern East Africa by examining plant leaf waxes in a marine sediment core that receives terrestrial runoff from the Limpopo River. The plant leaf wax records are compared to a multi-proxy sea surface temperature (SST) record and pollen assemblage data from the same site. We find that Indian Ocean SST variability, driven by high-latitude obliquity, exerted a strong control on the vegetation of southern East Africa during the past 800,000 yr. Interglacial periods were characterized by relatively wetter and warmer conditions, increased contributions of C3 vegetation, and higher SST, whereas glacial periods were marked by cooler and arid conditions, increased contributions of C4... |
| Tipo: Text |
Palavras-chave: Vegetation; Africa; N-alkane; Pollen; Subtropical Front; Mid-Brunhes. |
| Ano: 2016 |
URL: https://archimer.ifremer.fr/doc/00345/45601/45215.pdf |
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| Eynaud, Frederique; Malaize, Bruno; Zaragosi, Sebastien; De Vernal, Anne; Scourse, James; Pujol, Claude; Cortijo, Elsa; Grousset, Francis E.; Penaud, Aurelie; Toucanne, Samuel; Turon, Jean-louis; Auffret, Gerard. |
| During the late Quaternary, both external and internal forcings have driven major climatic shifts from glacial to interglacial conditions. Nonlinear climatic steps characterized the transitions leading to these extrema, with intermediate excursions particularly well expressed in the dynamics of the Northern Hemisphere cryosphere. Here we document the impact of these dynamics on the north-eastern North Atlantic Ocean, focussing on the 35-10 ka interval. Sea-surface salinities have been reconstructed quantitatively based on two independent methods from core MD95-2002, recovered from the northern Bay of Biscay adjacent to the axis of the Manche paleoriver outlet and thus in connection with proximal European ice sheets and glaciers. Quantitative... |
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| Ano: 2012 |
URL: http://archimer.ifremer.fr/doc/00086/19762/20100.pdf |
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| Turon, Jean-louis; Malaize, Bruno. |
| La Mission océanographique PICABIA MD 134 est la dernière d’un long périple entamé le 4 Mai 2003 avec la campagne PICASSO MD 132 (Paleoclimatology Isotopes Calypso pour les séries sédimentaires Océaniques) . A Brest la campagne SEDICAR (MD 133) a pris le relais avec trois étapes dans le Golfe de Gascogne : BREST –BREST (24/06- 28/06); Après une escale technique, le deuxième leg (12/07-14/07) a permis de relier Brest à Bordeaux (escale et cérémonies officielles des14 Juillet-15 Juillet). SEDICAR 3 a été réalisée entre Bordeaux et la sortie du Golfe de Gascogne.De fait, la campagne PICABIA -MD 134 (Paléoclimatology, Calypso sur la Bordure Ibérique et Africaine) a débuté officiellement le 19 Juillet à 0 :00 heure. Cette mission et les programmes français sont... |
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| Ano: 2003 |
URL: https://archimer.ifremer.fr/doc/00632/74458/74276.pdf |
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| Eynaud, Frederique; De Abreu, Lucia; Voelker, Antje; Schoenfeld, Joachim; Salgueiro, Emilia; Turon, Jean-louis; Penaud, Aurelie; Toucanne, Samuel; Naughton, Filipa; Goni, Maria Fernanda Sanchez; Malaize, Bruno; Cacho, Isabel. |
| This paper documents the migration of the Polar Front (PF) over the Iberian margin during some of the cold climatic extremes of the last 45 ka. It is based on a compilation of robust and coherent paleohydrological proxies obtained from eleven cores distributed between 36 and 42 degrees N. Planktonic delta O-18 (Globigerina bulloides), ice-rafted detritus concentrations, and the relative abundance of the polar foraminifera Neogloboquadrina pachyderma sinistral were used to track the PF position. These three data sets, compared from core to core, show a consistent evolution of the sea surface paleohydrology along the Iberian margin over the last 45 ka. We focused on five time slices representative of cold periods under distinct paleoenvironmental forcings:... |
| Tipo: Text |
Palavras-chave: Polar Front; LGM; Heinrich events. |
| Ano: 2009 |
URL: https://archimer.ifremer.fr/doc/00218/32909/31415.pdf |
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| Caley, Thibaut; Peeters, Frank J. C.; Biastoch, Arne; Rossignol, Linda; Van Sebille, Erik; Durgadoo, Jonathan; Malaize, Bruno; Giraudeau, Jacques; Arthur, Kristina; Zahn, Rainer. |
| The Indian-Atlantic water exchange south of Africa (Agulhas leakage) is a key component of the global ocean circulation. No quantitative estimation of the paleo-Agulhas leakage exists. We quantify the variability in interocean exchange over the past 640,000 years, using planktic foraminiferal assemblage data from two marine sediment records to define an Agulhas leakage efficiency index. We confirm the validity of our new approach with a numerical ocean model that realistically simulates the modern Agulhas leakage changes. Our results suggest that, during the past several glacial-interglacial cycles, the Agulhas leakage varied by ~10 sverdrup and more during major climatic transitions. This lends strong credence to the hypothesis that modifications in the... |
| Tipo: Text |
Palavras-chave: Quantitative palaeo Agulhas leakage; Planktic foraminiferal; Numerical ocean model; Overturning circulation. |
| Ano: 2014 |
URL: https://archimer.ifremer.fr/doc/00291/40172/39028.pdf |
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