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| Registros recuperados: 12 | |
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| Meland, My; Jansen, E; Elderfield, H; Dokken, Tm; Olsen, A; Bellerby, Rgj. |
| In core top samples in the Nordic Seas, Mg/Ca ratios of N. pachyderma ( sin.) are generally consistent with previous high-latitude calibration data but do not reflect the modern calcification temperature gradient from 2 degrees C in the northwest to 8 degrees C in the southeast. This is because Mg/Ca ratios in foraminiferal shells from the central Nordic Seas are similar to 0.4 mmol/mol higher than expected from calibrations of Nurnberg ( 1995) and Elderfield and Ganssen ( 2000). The enhanced Mg/Ca ratios are observed in an area with low sedimentation rates (< similar to 5 cm/kyr). Possible factors that may cause this include bioturbation, Holocene variability in old core tops, dissolution, pore water chemistry, occurrence of volcanic ash, and other... |
| Tipo: Text |
Palavras-chave: Planktonic foraminifera; N. pachyderma (sin.); Mg/Ca; Paleothermometry; Paleoceanography; Nordic Seas. |
| Ano: 2006 |
URL: https://archimer.ifremer.fr/doc/00234/34559/33319.pdf |
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| Incarbona, Alessandro; Dinares-turell, Jaume; Di Stefano, Enrico; Ippolito, Giuseppe; Pelosi, Nicola; Sprovieri, Rodolfo. |
| The Middle Pleistocene Transition (1.2-0.7 Ma) is the most recent re-organization of the global climate system which includes variations in the frequency and amplitude of glacial/interglacial cycles, increased ice sheet volume, sea surface temperature cooling and a significant drop in the CO2 atmospheric levels. Here we present high-resolution planktonic foraminifera data (mean sampling resolution of about 780 years) from core LC10 recovered in the Ionian Sea (eastern Mediterranean), between 1.2 and 0.9 Ma. Selected taxa, among them G. ruber, T. quinqueloba and G. bulloides, show significant periodicities that can be associated to orbital cycles, mainly precession and obliquity. The planktonic foraminifera based paleoclimatic curve exhibits a cooling... |
| Tipo: Text |
Palavras-chave: Middle Pleistocene Transition; Planktonic foraminifera; Ionian Sea; Orbital climate variability; Neogloboquadrina pachyderma sinistral coiling. |
| Ano: 2013 |
URL: https://archimer.ifremer.fr/doc/00181/29205/27581.pdf |
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| Pena, L. D.; Goldstein, S. L.; Hemming, S. R.; Jones, K. M.; Calvo, E.; Pelejero, C.; Cacho, I.. |
| The Southern Ocean is increasingly recognized as a key player in the general ocean thermohaline circulation and the global climate system during glacial interglacial transitions. In particular, the advection of Southern Ocean intermediate waters (SOIW), like Antarctic Intermediate Water and Sub-Antarctic Mode Water, to the Eastern Equatorial Pacific (EEP), through a so-called "oceanic tunnelling" mechanism, is an important means for rapid transfer of climatic signals (such as heat, fresh water, salt, and chemical species) from high-to-low latitudes. However, information on how intermediate water advection rates changed in the past, and particularly during deglaciations, is fragmentary. We present new results for Nd isotopes (epsilon(Nd)) in cleaned... |
| Tipo: Text |
Palavras-chave: Neodymium isotopes; Planktonic foraminifera; Intermediate water masses; Eastern Equatorial Pacific; Equatorial Undercurrent; Southern Ocean. |
| Ano: 2013 |
URL: https://archimer.ifremer.fr/doc/00264/37543/36928.pdf |
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| Farmer, Elizabeth J.; Chapman, Mark R.; Andrews, Julian E.. |
| A high-resolution record of Mg/Ca ratios from the planktonic foraminifer Globigerina bulloides has been produced for IMAGES core MD99-2251 from the subpolar North Atlantic. The record extends from the Younger Dryas-Preboreal transition through the Holocene at similar to 70 year resolution, with a more detailed section at similar to 20 year resolution through the interval encompassing the major cooling episode 8200 years ago. Mg/Ca derived temperatures show significant variations through the Holocene, with surface temperatures ranging from similar to 8 to 13 degrees C. The onset of the Holocene is marked by an abrupt warming, with a further increase in early Holocene temperatures occurring prior to 9.5 ka. This is followed by a mid-Holocene period of cooler... |
| Tipo: Text |
Palavras-chave: Planktonic foraminifera; Mg/Ca; G. bulloides; North Atlantic; Holocene. |
| Ano: 2008 |
URL: https://archimer.ifremer.fr/doc/00236/34760/33396.pdf |
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| Vautravers, Maryline J.; Shackleton, Nicholas J.. |
| The marine isotopic stage 3 (MIS3) at Ocean Drilling Program (ODP) Site 1060 (Gulf Stream) shows both sharp onset and end of interstadials, the existence of very short lived warm events during stadials, and points to differences in detail between the sea surface temperature (SST) record from the western North Atlantic and the atmospheric temperature record inferred from delta O-18 in Greenland ice. Investigating MIS3 and obtaining comparable data from other locations appears crucial. The eastern Atlantic provides well-documented records of climate changes. We have selected a core from off Portugal and use it to examine Dansgaard/Oeschger events (D/O) at centennial-scale resolution (139 years on average between two data points). We have obtained a faunal... |
| Tipo: Text |
Palavras-chave: SST; Planktonic foraminifera; Last glacial. |
| Ano: 2006 |
URL: https://archimer.ifremer.fr/doc/00234/34548/33352.pdf |
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| Morard, Raphael; Escarguel, Gilles; Weiner, Agnes K. M.; Andre, Aurore; Douady, Christophe J.; Wade, Christopher M.; Darling, Kate F.; Ujiie, Yurika; Seears, Heidi A.; Quillevere, Frederic; De Garidel-thoron, Thibault; De Vargas, Colomban; Kucera, Michal. |
| Investigations of biodiversity, biogeography, and ecological processes rely on the identification of "species" as biologically significant, natural units of evolution. In this context, morphotaxonomy only provides an adequate level of resolution if reproductive isolation matches morphological divergence. In many groups of organisms, morphologically defined species often disguise considerable genetic diversity, which may be indicative of the existence of cryptic species. The diversity hidden by morphological species can be disentangled through genetic surveys, which also provide access to data on the ecological distribution of genetically circumscribed units. These units can be identified by unique DNA sequence motifs and allow studies of evolutionary and... |
| Tipo: Text |
Palavras-chave: Cryptic species; Genetic diversity; Planktonic foraminifera; Molecular nomenclature; MOTUs. |
| Ano: 2016 |
URL: https://archimer.ifremer.fr/doc/00383/49408/49900.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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| Registros recuperados: 12 | |
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