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| Cleroux, Caroline; Cortijo, Elsa; Anand, Pallavi; Labeyrie, Laurent; Bassinot, Franck; Caillon, Nicolas; Duplessy, Jean-claude. |
| [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.... |
| Tipo: Text |
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| Ano: 2008 |
URL: https://archimer.ifremer.fr/doc/00237/34806/33325.pdf |
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| Marzin, C.; Kallel, Nejib; Kageyama, Masa; Duplessy, Jean-claude; Braconnot, Jean-claude. |
| Several paleoclimate records such as from Chinese loess, speleothems or upwelling indicators in marine sediments present large variations of the Asian monsoon system during the last glaciation. Here, we present a new record from the northern Andaman Sea (core MD77-176) which shows the variations of the hydrological cycle of the Bay of Bengal. The high-resolution record of surface water delta O-18 dominantly reflects salinity changes and displays large millennial-scale oscillations over the period 40 000 to 11 000 yr BP. Their timing and sequence suggests that events of high (resp. low) salinity in the Bay of Bengal, i.e. weak (resp. strong) Indian monsoon, correspond to cold (resp. warm) events in the North Atlantic and Arctic, as documented by the... |
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| Ano: 2013 |
URL: https://archimer.ifremer.fr/doc/00264/37572/36845.pdf |
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| Paterne, Martine; Kallel, Nejib; Labeyrie, Laurent; Vautravers, Maryline J.; Duplessy, Jean-claude; Rossignol-strick, Martine; Cortijo, Elsa; Arnold, Maurice; Fontugne, Michel. |
| 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... |
| Tipo: Text |
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| Ano: 1999 |
URL: https://archimer.ifremer.fr/doc/00239/35050/36799.pdf |
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| Boussetta, Soumaya; Kallel, Nejib; Bassinot, Franck; Labeyrie, Laurent; Duplessy, Jean-claude; Caillon, Nicolas; Dewilde, Fabien; Rebaubier, Helene. |
| 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... |
| Tipo: Text |
Palavras-chave: Mediterranean; Mg/Ca; Planktonic foraminifera; Sea surface Temperature; Salinity; Diagenesis; Vital effect. |
| Ano: 2012 |
URL: https://archimer.ifremer.fr/doc/00139/25047/23181.pdf |
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| Gottschalk, Julia; Riveiros, Natalia Vazquez; Waelbroeck, Claire; Skinner, Luke C.; Michel, Elisabeth; Duplessy, Jean-claude; Hodell, David; Mackensen, Andreas. |
| Epibenthic foraminifer delta C-13 measurements are valuable for reconstructing past bottom water dissolved inorganic carbon d13C (delta C-13(DIC)), which are used to infer global ocean circulation patterns. Epibenthic delta C-13, however, may also reflect the influence of C-13-depleted phytodetritus, microhabitat changes, and/or variations in carbonate ion concentrations. Here we compare the delta C-13 of two benthic foraminifer species, Cibicides kullenbergi and Cibicides wuellerstorfi, and their morphotypes, in three sub-Antarctic Atlantic sediment cores over several glacial-interglacial transitions. These species are commonly assumed to be epibenthic, living above or directly below the sediment-water interface. While this might be consistent with the... |
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| Ano: 2016 |
URL: https://archimer.ifremer.fr/doc/00421/53207/54927.pdf |
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| Cleroux, Caroline; Debret, Maxime; Cortijo, Elsa; Duplessy, Jean-claude; Dewilde, Fabien; Reijmer, John; Massei, Nicolas. |
| This study presents high-resolution foraminiferal-based sea surface temperature, sea surface salinity and upper water column stratification reconstructions off Cape Hatteras, a region sensitive to atmospheric and thermohaline circulation changes associated with the Gulf Stream. We focus on the last 10,000 years (10 ka) to study the surface hydrology changes under our current climate conditions and discuss the centennial to millennial time scale variability. We observed opposite evolutions between the conditions off Cape Hatteras and those south of Iceland, known today for the North Atlantic Oscillation pattern. We interpret the temperature and salinity changes in both regions as co-variation of activities of the subtropical and subpolar gyres. Around 8.3... |
| Tipo: Text |
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| Ano: 2012 |
URL: https://archimer.ifremer.fr/doc/00266/37681/36613.pdf |
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