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| Registros recuperados: 66 | |
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| Cortese, G.; Dunbar, G. B.; Carter, L.; Scott, G.; Bostock, H.; Bowen, M.; Crundwell, M.; Hayward, B. W.; Howard, W.; Martinez, J.l.; Moy, A.; Neil, H.; Sabaa, A.; Sturm, A.. |
| Paleoceanographic archives derived from 17 marine sediment cores reconstruct the response of the Southwest Pacific Ocean to the peak interglacial, Marine Isotope Stage (MIS) 5e (ca. 125ka). Paleo-Sea Surface Temperature (SST) estimates were obtained from the Random Forest modelan ensemble decision tree toolapplied to core-top planktonic foraminiferal faunas calibrated to modern SSTs. The reconstructed geographic pattern of the SST anomaly (maximum SST between 120 and 132ka minus mean modern SST) seems to indicate how MIS 5e conditions were generally warmer in the Southwest Pacific, especially in the western Tasman Sea where a strengthened East Australian Current (EAC) likely extended subtropical influence to ca. 45 degrees S off Tasmania. In contrast, the... |
| Tipo: Text |
Palavras-chave: Interglacial climate; Foraminifera; South Pacific Ocean; Marine Isotope Stage 5; Sea surface temperature. |
| Ano: 2013 |
URL: https://archimer.ifremer.fr/doc/00264/37492/36995.pdf |
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| Schmittner, Andreas; Bostock, Helen C.; Cartapanis, Olivier; Curry, William B.; Filipsson, Helena L.; Galbraith, Eric D.; Gottschalk, Julia; Carlos Herguera, Juan; Hoogakker, Babette; Jaccard, Samuel L.; Lisiecki, Lorraine E.; Lund, David C.; Martinez-mendez, Gema; Lynch-stieglitz, Jean; Mackensen, Andreas; Michel, Elisabeth; Mix, Alan C.; Oppo, Delia W.; Peterson, Carlye D.; Repschlaeger, Janne; Sikes, Elisabeth L.; Spero, Howard J.; Waelbroeck, Claire. |
| The carbon isotope composition (C-13) of seawater provides valuable insight on ocean circulation, air-sea exchange, the biological pump, and the global carbon cycle and is reflected by the C-13 of foraminifera tests. Here more than 1700 C-13 observations of the benthic foraminifera genus Cibicides from late Holocene sediments (C-13(Cibnat)) are compiled and compared with newly updated estimates of the natural (preindustrial) water column C-13 of dissolved inorganic carbon (C-13(DICnat)) as part of the international Ocean Circulation and Carbon Cycling (OC3) project. Using selection criteria based on the spatial distance between samples, we find high correlation between C-13(Cibnat) and C-13(DICnat), confirming earlier work. Regression analyses indicate... |
| Tipo: Text |
Palavras-chave: Carbon; Isotopes; Benthic; Foraminifera; Calibration. |
| Ano: 2017 |
URL: https://archimer.ifremer.fr/doc/00661/77326/78788.pdf |
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| Malaize, B.; Joly, C.; Venec-peyre, M. -t.; Bassinot, F.; Caillon, N.; Charlier, K.. |
| High-resolution faunal and isotopic analyses of foraminifera were performed on core MD96-2073 (10 degrees 94'N, 52 degrees 62'E, 3142 m depth), located close to Socotra Island in the upwelling area of the Somali Basin ( NW Indian Ocean). This work focuses on Marine Isotopic Stage 6.5 in order to reconstruct paleo-upwelling changes and their links with the Arabian Sea summer monsoon and the migration of the Intertropical Convergence Zone (ITCZ). Correspondence and cluster analyses of planktonic foraminiferal abundances, partly controlled by temperature and water mass productivity, together with an upwelling intensification index, show the occurrence of a strong upwelling between 176 and 165 ka. This upwelling intensification responds to a northward... |
| Tipo: Text |
Palavras-chave: Paleoclimatology; Foraminifera; Isotopes; Indian monsoon; ITCZ; Sapropels; Upwelling. |
| Ano: 2006 |
URL: https://archimer.ifremer.fr/doc/00234/34487/33433.pdf |
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| Rasmussen, Tl; Oppo, Dw; Thomsen, E; Lehman, Sj. |
| [1] Results from two deep sea cores from northeast of Newfoundland at 1251 and 2527 m water depth, respectively, indicate that during the time period from 160,000 to 10,000 years BP, ice rafting events in the Labrador Sea were accompanied by rapid variations in deep and surface water circulation. Twelve ice-rafting events occurred, each coinciding with high concentrations of detrital carbonate and oxygen isotopic depletion of both surface and bottom waters. Eleven of these can be correlated with the North Atlantic Heinrich events H1-H11. The remaining very conspicuous ice-rafting event took place early in MIS substage 5e, at a time when the planktic faunal assemblage suggests marked warming of the sea surface. In the shallower core, benthic delta(13)C... |
| Tipo: Text |
Palavras-chave: Paleoceanography; Labrador Sea; Ice rafting; Foraminifera; Last climate cycle. |
| Ano: 2003 |
URL: https://archimer.ifremer.fr/doc/00496/60768/65083.pdf |
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| Fontanier, Christophe; Koho, K. A.; Goni-urriza, M. S.; Deflandre, Bruno; Galaup, S.; Ivanovsky, A.; Gayet, Nicolas; Dennielou, Bernard; Gremare, Antoine; Bichon, S.; Gassie, C.; Anschutz, P.; Duran, R.; Reichart, G. J.. |
| We present ecological and isotopic (δ18O and δ13C) data on benthic foraminifera sampled from 4 deep-sea stations in a pockmark field from the deep-water Niger delta (Gulf of Guinea, Equatorial Atlantic Ocean). In addition, a series of sedimentological and (bio)geochemical data are shown to back up foraminiferal observations. All stations are located within 1.2 km of each other, so prevailing oceanographic conditions can be assumed to be similar at each site. Two of the sites (GMMC-01 and GMMC-02) are located in a pockmark (named “pockmark A”) where current methane seepages were recorded by ROV observations. A third station (GMMC-03) is located in the topographic depression interpreted as a collapsed pockmark (named “pockmark B”). The fourth site (GMMC-04)... |
| Tipo: Text |
Palavras-chave: Niger delta; Hydrate pockmark; Foraminifera; Stable isotopes; Bacteria. |
| Ano: 2014 |
URL: http://archimer.ifremer.fr/doc/00211/32194/30628.pdf |
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| Carrier, Vincent; Svenning, Mette M.; Grundger, Friederike; Niemann, Helge; Dessandier, Pierre-antoine; Panieri, Giuliana; Kalenitchenko, Dimitri. |
| Cold seeps are characterized by high biomass, which is supported by the microbial oxidation of the available methane by capable microorganisms. The carbon is subsequently transferred to higher trophic levels. South of Svalbard, five geological mounds shaped by the formation of methane gas hydrates, have been recently located. Methane gas seeping activity has been observed on four of them, and flares were primarily concentrated at their summits. At three of these mounds, and along a distance gradient from their summit to their outskirt, we investigated the eukaryotic and prokaryotic biodiversity linked to 16S and 18S rDNA. Here we show that local methane seepage and other environmental conditions did affect the microbial community structure and composition.... |
| Tipo: Text |
Palavras-chave: Arctic; Methane seeps; Prokaryotes; Methanotrophs; ANME; Sulfate-reducing bacteria; Eukaryotes; Foraminifera. |
| Ano: 2020 |
URL: https://archimer.ifremer.fr/doc/00667/77893/80077.pdf |
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| Favry, A; Guelorget, O; Debenay, Jp; Lefebvre, A; Perthuisot, Jp. |
| As part of a global investigation of foraminifera importance in the Mediterranean paralic realm, the distribution of present foraminifera in Kalloni Bay was studied through species determination and counting. From these basic data, density, species richness, Shannon Index and dominance were calculated for several stations covering the whole basin. In addition, a factorial analysis of correspondances between stations and species assemblages was performed. All these methods concur in showing that the organization of foraminifera populations follows sc principal longitudinal gradient from the entrance towards the most continental reaches and a subsidiary transverse gradient. When compared with sedimentological data, the distribution of foraminifera does not... |
| Tipo: Text |
Palavras-chave: Foraminifera; Paralic; Confinement; Greece; Present. |
| Ano: 1997 |
URL: http://archimer.ifremer.fr/doc/00093/20457/18129.pdf |
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| Firesinger, Devon Robert. |
| The development of an accurate and precise geochronology is imperative to understanding archives containing information about Earth’s past. Unable to date all intervals of an archive, researchers use methods of interpolation to approximate age between dates. Sections of the radiocarbon calibration curve can induce larger chronological uncertainty independent of instrumental precision, meaning even a precise date may carry inflated error in its calibration to a calendar age. Methods of interpolation range from step-wise linear regression to, most recently, Bayesian statistical models. These employ prior knowledge of accumulation rate to provide a more informed interpolation between neighboring dates. This study uses a Bayesian statistical accumulation model... |
| Tipo: Text |
Palavras-chave: Gas ion source; Accelerator mass spectrometry; Isotope dilution; Foraminifera; Pigmy Basin. |
| Ano: 2017 |
URL: https://archimer.ifremer.fr/doc/00494/60601/64087.pdf |
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| Ohkushi, K.; Kennett, J. P.; Zeleski, C. M.; Moffitt, S. E.; Hill, T. M.; Robert, Cyril; Beaufort, L.; Behl, R. J.. |
| The oxygen minimum zone (OMZ) of the late Quaternary California margin experienced abrupt and dramatic changes in strength and depth in response to changes in intermediate water ventilation, ocean productivity, and climate at orbital through millennial time scales. Expansion and contraction of the OMZ is exhibited at high temporal resolution (107-126 year) by quantitative benthic foraminiferal assemblage changes in two piston cores forming a vertical profile in Santa Barbara Basin (569 m, basin floor; 481 m, near sill depth) to 34 and 24 ka, respectively. Variation in the OMZ is quantified by new benthic foraminiferal groupings and new dissolved oxygen index based on documented relations between species and water-mass oxygen concentrations.... |
| Tipo: Text |
Palavras-chave: Oxygen minimum zone; Foraminifera; Ventilation; Oxygen index; Pacific; Hypoxia. |
| Ano: 2013 |
URL: https://archimer.ifremer.fr/doc/00264/37489/35811.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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| Snow, Tasha. |
| The Arctic and North Atlantic underwent significant climactic changes since the Last Glacial Maximum (25,000 years before present (1950 AD); ka BP), but offsets in the timing of events between the two regions are poorly constrained due to age model uncertainties that arise from changing radiocarbon reservoir ages. Here, we use a relatively high-resolution, multi-proxy stable isotope and sedimentologic dataset from Eastern Fram Strait (ODP Leg 162 Site 986) marine sediments to constrain the timing of Svalbard/Barents Sea Ice Sheet decay and infer deglacial reservoir ages over the last 30 ka. We use magnetic susceptibility, inorganic and organic carbon, foraminiferal assemblage counts, planktonic foraminiferal isotopes, and iceberg-rafted debris proxies to... |
| Tipo: Text |
Palavras-chave: Paleoceanography; Meltwater; Isotopes; Foraminifera; Fram Strait; Reservoir age. |
| Ano: 2014 |
URL: https://archimer.ifremer.fr/doc/00499/61045/64452.pdf |
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| Denoyelle, Marieva; Jorissen, Frans J.; Martin, Daniel; Galgani, Francois; Mine, Jacques. |
| We compare foraminifera and macrofauna as bio-indicators of oil-based drill mud disposal site off Congo. The most polluted sites are characterized by poor faunas, dominated by some very tolerant taxa. Slightly further from the disposal site, there is an area with strongly increased densities, heavily dominated by opportunistic taxa. Still further, macrofauna appears to be similar to that at the reference area, but the foraminiferal meiofauna still suggests a slight environmental perturbation. The foraminiferal FIEI index, based on the species distribution in the study area, appears to be more discriminative than the macrofaunal ITI index, based on a priori definitions of the trophic guilds of the various taxa. Our comparative approach allows us to point... |
| Tipo: Text |
Palavras-chave: Bio-indicators; Biotic index; Drilling mud; Foraminifera; Macrofauna. |
| Ano: 2010 |
URL: http://archimer.ifremer.fr/doc/00019/13027/10203.pdf |
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| Tmalla, A.F.A.. |
| The stratigraphic positions of the Wadi Dukhan and Al Uwayliah formations are reviewed. Diagnostic Maastrichtian larger foraminiferal species from the Wadi Dukhan Formation in well B7 – 41 (Cyrenaica) and in well U2 – 6 (northeastern Sirt Basin) are illustrated for the first time. These species are Omphalocyclus macroporus (Lamarck), Siderolites cf. calcitrapoides Lamarck and Orbitoides cf. media (d’Archiac). Following the rules of nomenclature, the type section of the Al Uwayliah Formation should be considered a composite stratotype. The section east of al Uwayliah village is the holostratotype (upper part of the formation) and the Jardas al Jarrari section is the parastratotype (lower part of the formation). The combined thickness of the two component... |
| Tipo: Article / Letter to the editor |
Palavras-chave: Maastrichtian; Paleocene; Northeast Libya; Stratigraphy; Foraminifera; 38.22; 42.79. |
| Ano: 2007 |
URL: http://www.repository.naturalis.nl/record/217418 |
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| Hofker, J.. |
| INTRODUCTION Of the bottom material collected by the Snellius-Expedition 78 samples contained Foraminifera. Many of these samples were extremely small, since they were gathered by means of piston core samplers; some were larger, as they were collected by means of a dredge; others were samples in shallow water at beaches or reefs. A l l samples were fixed in formaldehyde, so that after the 40 years they remained in store before they were studied, rests of protoplasma were seldom preserved. The numerous plankton samples, preserved in formaldehyde or in alcohol, did note contain planktonic Foraminifera; obviously the small amount of CaC03 in the samples caused the dissolution of the tests. The planktonic Foraminifera are not described here, as planktonic... |
| Tipo: Article / Letter to the editor |
Palavras-chave: Foraminifera; Indonesia; Snellius Expedition 30; 42.94. |
| Ano: 1978 |
URL: http://www.repository.naturalis.nl/record/323936 |
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| Registros recuperados: 66 | |
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