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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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| 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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| Dupont, Lydie M.; Caley, Thibaut; Castañeda, Isla S.. |
| Very little is known about the impact of atmospheric carbon dioxide pressure (pCO2) on the shaping of biomes. The development of pCO2 throughout the Brunhes Chron may be considered a natural experiment to elucidate relationships between vegetation and pCO2. While the glacial periods show low to very low values (~ 230 to ~ 190 ppmv, respectively), the pCO2 levels of the interglacial periods vary from intermediate to relatively high (~250 to ~ 270, respectively). To study the influence of pCO2 on the Pleistocene development of SE African vegetation, we used the pollen record of a marine core (MD96-2048) retrieved from Maputo Bay south of the Limpopo River mouth in combination with stable isotope and geochemical proxies. Applying endmember analysis, four... |
| Tipo: Text |
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| Ano: 2019 |
URL: https://archimer.ifremer.fr/doc/00485/59649/62677.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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| 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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| Caley, Thibaut; Zaragosi, S.; Bourget, Julien; Martinez, P.; Malaize, B.; Eynaud, F.; Rossignol, L.; Garlan, Thierry; Ellouz-zimmermann, Nadine. |
| The monsoon is one of the most important climatic phenomena: it promotes inter-hemispheric exchange of energy and affects the economical prosperity of several countries exposed to its seasonal seesaw. Previous studies in both the Indian and Asian monsoon systems have generally suggested a dominant northern hemispheric (NH) control on summer monsoon dynamics at the scale of suborbital-millennial climatic changes, while the forcing/response of Indian and Asian monsoons at the orbital scale remains a matter of debate. Here, six marine sediment cores distributed across the whole Arabian Sea are used to build a regional surface marine productivity signal. The productivity signal is driven by the intensity of Indian summer monsoon winds. Our results demonstrate... |
| Tipo: Text |
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| Ano: 2013 |
URL: https://archimer.ifremer.fr/doc/00274/38492/36962.pdf |
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