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| Registros recuperados: 29 | |
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| Ma, Ruifang; Sépulcre, Sophie; Licari, Laetitia; Haurine, Frédéric; Bassinot, Franck; Yu, Zhaojie; Colin, Christophe. |
| We have measured Cd / Ca ratios of several benthic foraminiferal species and studied benthic foraminiferal assemblages on two cores from the northern Indian Ocean (Arabian Sea and northern Bay of Bengal, BoB), in order to reconstruct variations in intermediate water circulation and paleo-nutrient content since the last deglaciation. Intermediate water Cdw records estimated from the benthic Cd / Ca reflect past changes in surface productivity and/or intermediate-bottom water ventilation. The benthic foraminiferal assemblages are consistent with the geochemical data. These results suggest that during the last deglaciation, the Heinrich Stadial 1 and Younger Dryas (HS1 and YD, respectively) millennial-scale events were marked by a decrease in Cdw values,... |
| Tipo: Text |
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| Ano: 2020 |
URL: https://archimer.ifremer.fr/doc/00659/77152/78525.pdf |
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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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| 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... |
| Tipo: Text |
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| Ano: 2014 |
URL: https://archimer.ifremer.fr/doc/00290/40149/39258.pdf |
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| Simon, Quentin; Thouveny, Nicolas; Bourles, Didier L.; Valet, Jean-pierre; Bassinot, Franck; Menabreaz, Lucie; Guillou, Valery; Choy, Sandrine; Beaufort, Luc. |
| Geomagnetic dipole moment variations associated with polarity reversals and excursions are expressed by large changes of the cosmogenic nuclide beryllium-10 (10Be) production rates. Authigenic 10Be/9Be ratios (proxy of atmospheric 10Be production) from oceanic cores therefore complete the classical information derived from relative paleointensity (RPI) records. This study presents new authigenic 10Be/9Be ratio results obtained from cores MD05-2920 and MD05-2930 collected in the west equatorial Pacific Ocean. Be ratios from cores MD05-2920, MD05-2930 and MD90-0961 have been stacked and averaged. Variations of the authigenic 10Be/9Be ratio are analyzed and compared with the geomagnetic dipole low series reported from global RPI stacks. The largest 10Be... |
| Tipo: Text |
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| Ano: 2016 |
URL: https://archimer.ifremer.fr/doc/00358/46910/46811.pdf |
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| Joussain, Ronan; Liu, Zhifei; Colin, Christophe; Duchamp-alphonse, Stephanie; Yu, Zhaojie; Moreno, Eva; Fournier, Lea; Zaragosi, Sebastien; Dapoigny, Arnaud; Meynadier, Laure; Bassinot, Franck. |
| Mineralogical and geochemical analyses conducted on cores located on the active channel-levee system of the northern Bengal Fan are used to establish changes in the weathering pattern and the sediment transport of the Himalayan system, and evaluate the effect of Indian summer monsoon rainfall during the Holocene. Our data indicate that during the Holocene, sediments from the northern Bengal Fan originate mainly from the G-B river system without any significant changes in the relative contribution of these rivers. From 9.8 to around 6 ka, relatively low smectite/(illite+chlorite) ratios and relatively high K/Si* ratios indicate high physical denudation rates of the Himalayan highlands together with a rapid transfer of the detrital material to the Bengal... |
| Tipo: Text |
Palavras-chave: Bengal Fan; Chemical weathering; Sr and Nd isotopic compositions; Physical erosion; Clay mineralogy. |
| Ano: 2017 |
URL: https://archimer.ifremer.fr/doc/00393/50416/51143.pdf |
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| Simon, Quentin; Thouveny, Nicolas; Bourles, Didier L.; Bassinot, Franck; Savranskaia, Tatiana; Valet, Jean-pierre. |
| New high-resolution authigenic 10Be/9Be ratio (Be-ratio) records covering the last geomagnetic reversal, i.e. the Matuyama–Brunhes transition (MBT), have been obtained and set on a time scale using benthic δ18 O (Cibicides wuellerstorfi) records. The geographic distribution of the four studied sites allows global comparison between the North Atlantic, Indian and Pacific Oceans. All Be-ratio records contain a two-fold increase triggered by the geomagnetic dipole moment (GDM) collapse associated with the MBT. The stratigraphic position of the Be-ratio spike, relative to marine isotope stages, allows establishment of a robust astrochronological framework for the MBT, anchoring its age between 778 and 766 ka (average mid-peaks at 772 ka), which is consistent... |
| Tipo: Text |
Palavras-chave: Authigenic Be-10/Be-9 ratio; Geomagnetic dipole moment minimum; Matuyama-Brunhes transition (MBT); Geomagnetic polarity reversal; Marine isotope stage 19; Atmospheric Be-10 production rates. |
| Ano: 2018 |
URL: https://archimer.ifremer.fr/doc/00430/54150/55510.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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| Levi, Camille; Labeyrie, Laurent; Bassinot, Franck; Guichard, Francois; Cortijo, Elsa; Waelbroeck, Claire; Caillon, Nicolas; Duprat, Josette; De Garidel-thoron, Thibault; Elderfield, Harry. |
| 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... |
| Tipo: Text |
Palavras-chave: Rapid climate changes; Low-latitude hydrological cycle; Last deglaciation. |
| Ano: 2007 |
URL: https://archimer.ifremer.fr/doc/00235/34611/32960.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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| Tanty, Cyrielle; Valet, Jean-pierre; Carlut, Julie; Bassinot, Franck; Zaragosi, Sebastien. |
| Turbiditic events are mostly avoided in paleomagnetic studies and therefore their remanence and magnetic properties are poorly described. Turbidites are exempt of bioturbation and potentially provide pertinent information about depositional remanence. We studied four quaternary turbidites of different origins in marine sediment cores. Upward fining of both magnetic and sedimentary fractions indicates that coarser grains reached the bottom first. We observe a progressive shallowing of the magnetic inclinations between the upper and bottom layers of the turbidites that increases with the size of the events and obeys a simple linear scaling law. Measurements of magnetic anisotropy suggest that hydrodynamic conditions prevailing during deposition seem to be... |
| Tipo: Text |
Palavras-chave: Detrital remanence; Turbidite; Sediment; Rock magnetism; Magnetization. |
| Ano: 2016 |
URL: https://archimer.ifremer.fr/doc/00421/53226/54792.pdf |
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| Nouet, Julius; Bassinot, Franck. |
| Several authors suggested that the thinning, with increasing depth of deposition, of calcite X-ray diffractometry (XRD) peaks obtained on planktonic foraminifera tests resulted from the preferential removal of their poorly crystallized parts as dissolution increases. By deconvolving XRD peak (104) from Globorotalia tumida (surface sediments, Sierra Leone Rise depth transect), we show that the full width at midheight does not depend only upon crystallinity, but reflects also the chemical and structural heterogeneity of foraminifera tests, which results in closely spaced, individual (104) diffraction peaks corresponding to phases with slightly different Mg contents. G. tumida contains two calcite phases: a well crystallized, Mg-poor calcite and a poorly... |
| Tipo: Text |
Palavras-chave: Dissolution; Foraminifera; X-ray diffraction; Crystallinity; Deconvolution. |
| Ano: 2007 |
URL: https://archimer.ifremer.fr/doc/00235/34626/32973.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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| Savranskaia, Tatiana; Egli, Ramon; Valet, Jean-pierre; Bassinot, Franck; Meynadier, Laure; Bourlès, Didier L.; Simon, Quentin; Thouveny, Nicolas. |
| Reconstructions of the global production rate of the cosmogenic isotope 10Be from sedimentary records of authigenic 10Be/9Be ratios have been successfully used to obtain independent estimates of geomagnetic dipole moment variations caused by field excursions or reversals. In this study, we assess the reliability of 10Be/9Be as a proxy for the cosmogenic 10Be production rate by evaluating two potential biasing sources represented by sediment composition and climatic modulation. For this purpose, we compare five high-resolution 10Be/9Be records of the Matuyama-Brunhes (M-B) field reversal from sediment cores of the Indian, West Pacific, and North Atlantic oceans. Significant increase of 10Be/9Be ratios at 774 ka is explained in terms of the dominant control... |
| Tipo: Text |
Palavras-chave: Cosmogenic nuclides; Beryllium; Authigenic; 10Be/9Be ratio; Geomagnetic field intensity; Matuyama-brunhes reversal. |
| Ano: 2021 |
URL: https://archimer.ifremer.fr/doc/00682/79399/81939.pdf |
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| Mathien-blard, Elise; Bassinot, Franck. |
| Mg/Ca in foraminiferal calcite has recently been extensively used to estimate past oceanic temperatures. Here we show, however, that the Mg/Ca temperature relationship of the planktonic species Globigerinoides ruber is significantly affected by seawater salinity, with a + 1 psu change in salinity resulting in a + 1.6 degrees C bias in Mg/Ca temperature calculations. If not accounted for, such a bias could lead, for instance, to systematic overestimations of Mg/Ca temperatures during glacial periods, when global ocean salinity had significantly increased compared to today. We present here a correction procedure to derive unbiased sea surface temperatures (SST) and delta O-18(sw) from G. ruber T-Mg/Ca and delta O-18(f) measurements. This correction procedure... |
| Tipo: Text |
Palavras-chave: Mg/Ca thermometry. |
| Ano: 2009 |
URL: https://archimer.ifremer.fr/doc/00218/32905/31418.pdf |
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| Cornuault, Marine; Tachikawa, Kazuyo; Vidal, Laurence; Guihou, Abel; Siani, Giuseppe; Deschamps, Pierre; Bassinot, Franck; Revel, Marie. |
| The Eastern Mediterranean Sea (EMS) is a key region to study circulation change because of its own thermohaline circulation. In this study, we focused on intermediate/deep water circulation since the Last Glacial Maximum (LGM) including the sapropel S1 period. Two cores from the Levantine Sea and the Strait of Sicily, respectively, collected at 1,780 m and 771 m water depth, were studied using Nd-143/Nd-144 (epsilon(Nd)) of foraminiferal tests and leachates as well as benthic foraminiferal stable isotopes (delta C-13, delta O-18). This approach allowed the determination of variations in (1) the North Atlantic water contribution to the Mediterranean basin, (2) water exchanges at the Strait of Sicily, and (3) the influence of the Nile River over the last... |
| Tipo: Text |
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| Ano: 2018 |
URL: https://archimer.ifremer.fr/doc/00496/60789/64957.pdf |
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| Bassinot, Franck; Beaufort, Luc; Vincent, Edith; Labeyrie, Laurent; Rostek, Frauke; Muller, Pj; Quidelleur, Xavier; Lancelot, Y. |
| 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... |
| Tipo: Text |
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| Ano: 1994 |
URL: https://archimer.ifremer.fr/doc/00100/21114/37251.pdf |
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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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| Moreno, Eva; Bassinot, Franck; Baudin, Francois; Venec-peyre, Marie-therese. |
| [1] A multiproxy study of core MD98-2166 makes it possible to investigate the influence of orbital forcing and sea level changes on Timor Sea sedimentation during the last 260 ka. Spectral analysis reveals a strong imprint of obliquity in all proxies. This is particularly puzzling for the CaCO(3) and total organic carbon (TOC) records since recent data obtained on nearby core MD01-2378, collected at a shallower water depth, showed a concentration of spectral power in the eccentricity and precession bands. Our results suggest that while sedimentary record in shallower core MD01-2378 shows a clear low-latitude response, that of core MD98-2166 reflects a stronger influence of high-latitude forcing through deepwater changes. In addition, Rock-Eval analyses... |
| Tipo: Text |
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| Ano: 2008 |
URL: https://archimer.ifremer.fr/doc/00238/34885/33152.pdf |
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| Yu, Zhaojie; Colin, Christophe; Bassinot, Franck; Wan, Shiming; Bayon, Germain. |
| Chemical weathering of silicate rocks on continents is thought to have played an important role in the evolution of past atmospheric carbon dioxide over geologic timescales. However, the detailed links between continental weathering and climate change over shorter timescales, and their potential impact on sediment records deposited in the ocean, remain poorly understood. Here, we present clay mineralogy and strontium‐neodymium isotopic data for marine sediment records from the Northern Indian Ocean, with the aim of investigating the weathering response of large Himalayan river basins to orbital and millennial climate forcing. We show that past glaciated episodes of the late Quaternary corresponded to periods of increased physical erosion, associated with... |
| Tipo: Text |
Palavras-chave: Climate change<; /AUTHOR_KEYWORD>; Continental weathering<; /AUTHOR_KEYWORD>; Highlands and floodplains<; /AUTHOR_KEYWORD>; Carbon cycle<; /AUTHOR_KEYWORD>; Himalaya<; /AUTHOR_KEYWORD>. |
| Ano: 2020 |
URL: https://archimer.ifremer.fr/doc/00632/74434/74154.pdf |
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| Registros recuperados: 29 | |
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