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| Simon, Quentin; Bourles, Didier L.; Bassinot, Franck; Nomade, Sebastien; Marino, Maria; Ciaranfi, Neri; Girone, Angela; Maiorano, Patrizia; Thouveny, Nicolas; Choy, Sandrine; Dewilde, Fabien; Scao, Vincent; Isguder, Gulay; Blamart, Dominique; Aster Team,. |
| Geomagnetic dipole moment (GDM) lows associated with polarity reversals or geomagnetic excursions induce significant modulation of the cosmogenic nuclide Beryllium-10 (Be-10) production. Hence, the reconstruction of atmospheric Be-10 production rates from natural archives such as marine sedimentary sequences or ice cores constitutes a complementary approach, independent from paleomagnetic measurements, to decipher past GDM fluctuations. This is particularly important in the Montalbano Jonico succession (South Italy) since it is candidate to host the Global Stratotype Section and Point of the Middle Pleistocene Stage but where the magnetostratigraphic positioning of the Matuyama-Brunhes boundary (MBB) has not been available up to now. This study presents... |
| Tipo: Text |
Palavras-chave: Be-10 cosmogenic nuclide; Authigenic Be-10/Be-9 ratio; Matuyama Brunhes Boundary (MBB); High-resolution oxygen isotope stratigraphy; MIS 19; GSSP stratotype. |
| Ano: 2017 |
URL: https://archimer.ifremer.fr/doc/00420/53183/55042.pdf |
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| Siani, Giuseppe; Michel, Elisabeth; De Pol-holz, Ricardo; Devries, Tim; Lamy, Frank; Carel, Melanie; Isguder, Gulay; Dewilde, Fabien; Lourantou, Anna. |
| The Southern Ocean plays a prominent role in the Earth's climate and carbon cycle. Changes in the Southern Ocean circulation may have regulated the release of CO2 to the atmosphere from a deep-ocean reservoir during the last deglaciation. However, the path and exact timing of this deglacial CO2 release are still under debate. Here we present measurements of deglacial surface reservoir C-14 age changes in the eastern Pacific sector of the Southern Ocean, obtained by C-14 dating of tephra deposited over the marine and terrestrial regions. These results, along with records of foraminifera benthic-planktic C-14 age and delta C-13 difference, provide evidence for three periods of enhanced upwelling in the Southern Ocean during the last deglaciation, supporting... |
| Tipo: Text |
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| Ano: 2013 |
URL: https://archimer.ifremer.fr/doc/00263/37472/36804.pdf |
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| Liu, Wei; Baudin, Francois; Moreno, Eva; Dewilde, Fabien; Caillon, Nicolas; Fang, Nianqiao; Bassinot, Franck. |
| Total organic carbon (TOC) and calcium carbonate (CaCO3) records from different water depths in the Timor Sea (NE Indian Ocean) are compared in order to better reconstruct past changes in pelagic productivity, highlight the impact of preservation at depth, and unravel the interplay of organic carbon and carbonate sedimentation. New data are presented for core MD01-2376 located at 2376 m depth. These results are compared, over the last 240 ka, with published data on two neighboring cores (MD01-2378, 1783 m and MD98-2166, 3875 m). TOC fluctuations show strong glacial/interglacial variations and Milankovitch-type oscillations (i.e., dominant frequencies centered on the 100, 41, and 23 ka bands), with an enrichment during cold periods that reflects an increase... |
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| Ano: 2014 |
URL: https://archimer.ifremer.fr/doc/00290/40149/39258.pdf |
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| Bouilloux, Alexandra; Valet, Jean-pierre; Bassinot, Franck; Joron, Jean-louis; Blanc-valleron, Marie-madeleine; Moreno, Eva; Dewilde, Fabien; Kars, Myriam; Lagroix, France. |
| Large changes in magnetic mineral concentration dependent parameters by more than 1 order of magnitude occur over 50-150 cm intervals in two marine sediment cores from the oxygen minimum zone in the Gulf of Aden. High-resolution sedimentological and chemical analyses indicate that these intervals are not associated with turbiditic events or sediment reworking, they do not result from changes in carbonate dilution or differences in sediment properties, and they do not correspond to volcanic layers. Magnetic mineralogical analyses reveal a change in magnetic mineral concentration from a magnetite-goethite assemblage to pure magnetite within the peak. The peaks almost disappear when the abundance of magnetic minerals is calculated after correcting for the... |
| Tipo: Text |
Palavras-chave: Paleomagnetism; Paleoenvironment; Goethite; Magnetite; Indian ocean. |
| Ano: 2013 |
URL: https://archimer.ifremer.fr/doc/00264/37488/36828.pdf |
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| Govin, Aline; Michel, Elisabeth; Labeyrie, Laurent; Waelbroeck, Claire; Dewilde, Fabien; Jansen, Eystein. |
| 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... |
| Tipo: Text |
Palavras-chave: Isotope substage 5E; Ice core; Interglacial period; Climate variability; Deep ocean; Atlantic; Sea; Circulation; Temperature; Hemisphere. |
| Ano: 2009 |
URL: https://archimer.ifremer.fr/doc/00208/31952/30375.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... |
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| Ano: 2012 |
URL: https://archimer.ifremer.fr/doc/00266/37681/36613.pdf |
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| Valet, Jean-pierre; Moreno, Eva; Bassinot, Franck; Johannes, Lola; Dewilde, Fabien; Bastos, Tiago; Lefort, Apolline; Venec-peyre, Marie-therese. |
| High resolution measurements of climatic and magnetic parameters have been performed on two cores from the eastern China Sea and the western Caroline Basin. On both cores, magnetic parameters show a strong imprint of climatic changes but the absence of relationship between the inclination and the bulk density indicates that the directional changes do not depend on lithology. A weak 100 ka cycle is present in the China sea inclination variations, but this period is not in phase with the orbital eccentricity and thus not relevant. All normalization parameters yielded similar estimates of relative paleointensity (RPI), but we have noticed the persistence of climatic components in the signal. Principal Component Analysis (PCA) applied to different parameters... |
| Tipo: Text |
Palavras-chave: Magnetization; Paleointensity; Paleomagnetism; Sediments. |
| Ano: 2011 |
URL: https://archimer.ifremer.fr/doc/00227/33818/32481.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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| Peral, Marion; Daeron, Mathieu; Blamart, Dominique; Bassinot, Franck; Dewilde, Fabien; Smialkowski, Nicolas; Isguder, Gulay; Bonnin, Jerome; Jorissen, Frans; Kissel, Catherine; Michel, Elisabeth; Vazquez Riveiros, Natalia; Waelbroeck, Claire. |
| Accurate reconstruction of past ocean temperatures is of critical importance to paleoclimatology. Carbonate clumped isotope thermometry (“Δ47”) is a relatively recent technique based on the strong relationship between calcification temperature and the statistical excess of 13C-18O bonds in carbonates. Its application to foraminifera holds great scientific potential, particularly because Δ47 paleotemperature reconstructions do not require assumptions regarding the 18O composition of seawater. However there are still relatively few published observations investigating the potential influence of parameters such as salinity or foraminiferal size and species. We present a new calibration data set based on 234 replicate analyses of 9 planktonic and 2 benthic... |
| Tipo: Text |
Palavras-chave: Carbonate clumped isotopes; Foraminifera; Paleothermometry. |
| Ano: 2018 |
URL: https://archimer.ifremer.fr/doc/00450/56134/57676.pdf |
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