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| Registros recuperados: 21 | |
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| De Vernal, A; Hillaire-marcel, C; Peltier, Wr; Weaver, Aj. |
| During the Last Glacial Maximum, the northwestern North Atlantic constituted a major conduit for Labrador and Greenland ice sheet meltwaters. Vertical density gradients in its upper water masses have been reconstructed by combining information from transfer functions based on dinocysts and from oxygen isotope measurements (delta(18)O) in planktonic foraminifera. Transfer functions yield temperature and salinity and thus potential density (sigma(theta)) for the warmest (August) and coldest (February) months in the photic zone. The delta(18)O values in different size fractions of epipelagic (Globigerina bulloides) and mesopelagic (Neogloboquadrina pachyderma left-coiled (Np1)) foraminifera allow us to assess sigma(theta) gradients through the pycnocline... |
| Tipo: Text |
Palavras-chave: Last Glacial Maximum; LGM; North Atlantic; Salinity; Density; Pycnocline. |
| Ano: 2002 |
URL: https://archimer.ifremer.fr/doc/00223/33405/31861.pdf |
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| Howe, Jacob N. W.; Piotrowski, Alexander M.; Hu, Rong; Bory, Aloys. |
| Radiogenic neodymium isotopes have been used as a water mass mixing proxy to investigate past changes in ocean circulation. Here we present a new depth transect of deglacial neodymium isotope records measured on uncleaned planktic foraminifera from five cores spanning from 3300 to 4900 m on the Mauritanian margin, in the tropical eastern Atlantic as well as an additional record from 4000 m on the Ceara Rise in the equatorial western Atlantic. Despite being located under the Saharan dust plume, the eastern Atlantic records differ from the composition of detrital inputs through time and exhibit similar values to the western Atlantic foraminiferal Nd across the deglaciation. Therefore we interpret the foraminiferal values as recording deep water Nd isotope... |
| Tipo: Text |
Palavras-chave: Neodymium isotopes; Last Glacial Maximum; Eastern Atlantic; Western Atlantic. |
| Ano: 2017 |
URL: https://archimer.ifremer.fr/doc/00497/60829/64501.pdf |
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| Jouet, Gwenael; Berne, Serge; Rabineau, Marina; Bassetti, Maria-angela; Bernier, P.; Dennielou, Bernard; Sierro, F.j.; Flores, J.a.; Taviani, M.. |
| The BourcartHérault canyon interfluve in the Gulf of Lions (NW Mediterranean) was the site of very high sedimentation (up to 2.5 m/kyr) around the Last Glacial Maximum, due to the vicinity of major fluvial systems that fed the shelf edge. Shoreface deposits and offshore muds deposited during each glacial/interglacial 100 kyr-cycle, created a repeated motif with high-angle and low-angle clinoforms on seismic profiles. New detailed morphological, sedimentological and paleo-environmental data, constrained by 14C dating, allow us to propose a scenario for the evolution of this critical area between 46 and 15 cal. kyr BP. The major seismic sequence (S5), formed as a forced regression during the overall sea-level fall between MIS-3 and MIS-2, can be sub-divided... |
| Tipo: Text |
Palavras-chave: Heinrich events; Western Mediterranean; High resolution sedimentary record; Relative sea level; Last Glacial Maximum. |
| Ano: 2006 |
URL: http://archimer.ifremer.fr/doc/2006/publication-2328.pdf |
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| De Deckker, P.; Moros, M.; Perner, K.; Blanz, T.; Wacker, L.; Schneider, R.; Barrows, T.t.; O’loingsigh, T.; Jansen, E.. |
| The Quaternary is well known for being a period of the geological record that saw significant and alternating climatic fluctuations. Here, we concentrate on the last 94 millennia that saw Australia and its surrounding seas undergo significant environmental changes. Importantly also it is during that this period of time includes the arrival and settlement of humans in Australia. Following on from Marine Isotopic Stage 4 (MIS4) that saw, over the period of 71-59 ka BP, a significant eustatic sea level drop (similar to 100 m), low sea-surface temperatures as well as glacial conditions on land, Australia experienced wet conditions again, but eventually progressively entered into a glacial phase. By then, humans had arrived on this large continent and later the... |
| Tipo: Text |
Palavras-chave: Oceanic fronts; Leeuwin Current; Foraminifer faunal analysis; Marine isotopic stages; Last Glacial Maximum; Palaeoceanography; Sea-surface temperature; Moraines; Modern analogue technique; Subantarctic Front; G. ruber. |
| Ano: 2020 |
URL: https://archimer.ifremer.fr/doc/00657/76931/78127.pdf |
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| Ho, Sze Ling; Laepple, Thomas. |
| Knowledge of the magnitude of the Last Glacial Maximum (LGM) cooling is a useful constraint for estimating the climate sensitivity used in projecting future climate change. Proxy comparison, especially that between the alkenone-based U-37(K ') and the archaeal tetraether-based TEX86, has been increasingly applied in paleoceanographic studies as a measure to better constrain proxy-derived temperature estimates. In this study, we compile and compare published multiproxy (U-37(K ') and TEX86H) records of glacial cooling measured on the same sediment cores. In spite of the diversity in oceanographic and sedimentation settings spanned by the study sites, we find that the TEX86H-derived mean tropical LGM cooling is approximately twice as strong as that suggested... |
| Tipo: Text |
Palavras-chave: Last Glacial Maximum; Sea surface temperature; Multiproxy; PMIP3; U-37(K '); TEX86H. |
| Ano: 2015 |
URL: https://archimer.ifremer.fr/doc/00352/46297/45933.pdf |
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| Sanchez, Gloria E.; Lange, Carina B.; Flores, Jose-abel; Caniupan, Magaly; Lamy, Frank. |
| We present a new record of coccolithophore (coccoliths) export productivity for the past 30,000 years based on the study of a marine sediment core collected at the western entrance of the Strait of Magellan (Core MD07-3128; 53 degrees S, 75 degrees W). This sediment core revealed the presence of an assemblage composed by thirteen coccolithophore taxa, dominated by small Gephyrocapsa (> 80% of the total assemblage on the average) and accompanied, in less proportions (1-10%), by two morphotypes of Emiliana huxleyi, Coccolithus pelagicus and Calcidiscus leptoporus. Coccolith concentration and CaCO3 content were strongly correlated (P << 0.01; R-2 = 0.63). In general, both records were in phase with alkenone-derived sea-surface temperature (Caniupan... |
| Tipo: Text |
Palavras-chave: Coccolithophores; Last Glacial Maximum; Holocene; Southern Chile. |
| Ano: 2014 |
URL: https://archimer.ifremer.fr/doc/00289/40052/38797.pdf |
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| Mackintosh, Andrew N.; Verleyen, Elie; O'Brien, Philip E.; White, Duanne A.; Jones, R. Selwyn; Mckay, Robert; Dunbar, Robert; Gore, Damian B.; Fink, David; Post, Alexandra L.; Miura, Hideki; Leventer, Amy; Goodwin, Ian; Hodgson, Dominic A.; Lilly, Katherine; Crosta, Xavier; Golledge, Nicholas R.; Wagner, Bernd; Berg, Sonja; Van Ommen, Tas; Zwartz, Dan; Roberts, Stephen J.; Vyverman, Wim; Masse, Guillaume. |
| The East Antarctic Ice Sheet (EAIS) is the largest continental ice mass on Earth, and documenting its evolution since the Last Glacial Maximum (LGM) is important for understanding its present-day and future behaviour. As part of a community effort, we review geological evidence from East Antarctica that constrains the ice sheet history throughout this period (similar to 30,000 years ago to present). This includes terrestrial cosmogenic nuclide dates from previously glaciated regions, C-14 chronologies from glacial and post-glacial deposits onshore and on the continental shelf, and ice sheet thickness changes inferred from ice cores and continental-scale ice sheet models. We also include new C-14 dates from the George V Land Terre Adelie Coast shelf. We... |
| Tipo: Text |
Palavras-chave: Antarctica; Last Glacial Maximum; Ice sheet; Sea level rise. |
| Ano: 2014 |
URL: https://archimer.ifremer.fr/doc/00290/40085/39171.pdf |
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| Mendelova, M.; Hein, A. S.; Mcculloch, R.; Davies, B.. |
| This paper reviews published geochronological data on glacier fluctuations and environmental changes in central Patagonia (44 degrees S-49 degrees S) from the Last Glacial Maximum (LGM) through to the Holocene. Well-dated glacial chronologies from the southern mid-latitudes can inform on the synchronicity of glacial advances worldwide and provide insight on the drivers of southern hemisphere glaciations. In central Patagonia, two large outlet lobes of the former Patagonian Ice Sheet advanced in broad synchrony with the global LGM. In contrast to other parts of Patagonia, there is no convincing evidence for a more extensive local LGM advance during Marine Isotope Stage 3. Deglaciation initiated at ca. 19 ka, earlier than in other parts of Patagonia and... |
| Tipo: Text |
Palavras-chave: Last Glacial Maximum; Deglaciation; Holocene; Patagonia; Glacial chronology. |
| Ano: 2017 |
URL: https://archimer.ifremer.fr/doc/00497/60830/64500.pdf |
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| Pflaumann, U; Sarnthein, M; Chapman, M; D'Abreu, L; Funnell, B; Huels, M; Kiefer, T; Maslin, M; Schulz, H; Swallow, J; Van Kreveld, S; Vautravers, M; Vogelsang, E; Weinelt, M. |
| The response of the tropical ocean to global climate change and the extent of sea ice in the glacial nordic seas belong to the great controversies in paleoclimatology. Our new reconstruction of peak glacial sea surface temperatures (SSTs) in the Atlantic is based on census counts of planktic foraminifera, using the Maximum Similarity Technique Version 28 (SIMMAX-28) modern analog technique with 947 modern analog samples and 119 well-dated sediment cores. Our study compares two slightly different scenarios of the Last Glacial Maximum (LGM), the Environmental Processes of the Ice Age: Land, Oceans, Glaciers (EPILOG), and Glacial Atlantic Ocean Mapping (GLAMAP 2000) time slices. The comparison shows that the maximum LGM cooling in the Southern Hemisphere... |
| Tipo: Text |
Palavras-chave: Last Glacial Maximum; Atlantic sea-surface temperatures; Seasonality; Sea ice cover; Glacial cooling near equator; Glacial upwelling intensity. |
| Ano: 2003 |
URL: https://archimer.ifremer.fr/doc/00225/33668/32070.pdf |
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| Lippold, Jorg; Gutjahr, Marcus; Blaser, Patrick; Christner, Emanuel; Ferreria, Maria Luiza De Carvalho; Mulitza, Stefan; Christl, Marcus; Wombacher, Frank; Böhm, Evelyn; Antz, Benny; Cartapanis, Olivier; Vogel, Hendrik; Jaccard, Samuel L.. |
| Reconstructing past modes of ocean circulation is an essential task in paleoclimatology and paleoceanography. To this end, we combine two sedimentary proxies, Nd isotopes (epsilon(Nd)) and the Pa-231/Th-230 ratio, both of which are not directly involved in the global carbon cycle, but allow the reconstruction of water mass provenance and provide information about the past strength of overturning circulation, respectively. In this study, combined Pa-231/Th-230 and epsilon(Nd) down-core profiles from six Atlantic Ocean sediment cores are presented. The data set is complemented by the two available combined data sets from the literature. From this we derive a comprehensive picture of spatial and temporal patterns and the dynamic changes of the Atlantic... |
| Tipo: Text |
Palavras-chave: Pa-231/Th-230; Epsilon(Nd); Atlantic Meridional Overturning Circulation; Deep sea sediments; Last Glacial Maximum; Deglaciation. |
| Ano: 2016 |
URL: https://archimer.ifremer.fr/doc/00421/53236/54762.pdf |
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| Waelbroeck, C.; Kiefer, T.; Dokken, T.; Chen, M. -t.; Spero, H. J.; Jung, S.; Weinelt, M.; Kucera, M.; Paul, A.. |
| Estimates of the change in surface seawater delta O-18 (delta O-18(sw)) between the Last Glacial Maximum (LGM) and Late Holocene (LH) are derived from homogenous data sets with rigorous age control, namely MARGO sea surface temperature (SST) estimates and oxygen isotopic ratios (delta O-18) of planktonic foraminifers. Propagation of uncertainties associated with each proxy allows the identification of robust patterns of change in delta O-18(sw). Examination of these patterns on a regional scale highlights which changes in surface currents and hydrological cycle are consistent with both planktonic isotopic data and reconstructed SST. Positive local annual mean LGM-LH delta O-18(sw) anomalies characterize the glacial tropical Indian Ocean, portions of the... |
| Tipo: Text |
Palavras-chave: Paleoceanography; Surface water oxygen isotopic ratio; Planktonic foraminifers; Last Glacial Maximum. |
| Ano: 2014 |
URL: https://archimer.ifremer.fr/doc/00297/40870/39909.pdf |
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| Boavida, Joana; Becheler, Ronan; Choquet, Marvin; Frank, Norbert; Taviani, Marco; Bourillet, Jean-francois; Meistertzheim, Anne‐leila; Grehan, Anthony; Savini, Alessandra; Arnaud-haond, Sophie. |
| Aim To infer cold‐water corals’ (CWC) post‐glacial phylogeography and assess the role of Mediterranean Sea glacial refugia as origins for the recolonization of the northeastern Atlantic Ocean. Location Northeastern Atlantic Ocean and Mediterranean Sea. Taxon Lophelia pertusa, Madrepora oculata. Methods We sampled CWC using remotely operated vehicles and one sediment core for coral and sediment dating. We characterized spatial genetic patterns (microsatellites and a nuclear gene fragment) using networks, clustering and measures of genetic differentiation. Results Inferences from microsatellite and sequence data were congruent, and showed a contrast between the two CWC species. Populations of L. pertusa present a dominant pioneer haplotype, local haplotype... |
| Tipo: Text |
Palavras-chave: Cold-water corals; Deep-sea; Glacial marine refugia; Last Glacial Maximum; Lophelia pertusa; Madrepora oculata; Marine phylogeography. |
| Ano: 2019 |
URL: https://archimer.ifremer.fr/doc/00487/59864/63140.pdf |
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| Voelker, A. H. L.; De Abreu, L.; Schoenfeld, J.; Erlenkeuser, H.; Abrantes, F.. |
| The surface water hydrography along the western Iberian margin, as part of the North Atlantic's eastern boundary upwelling system, consists of a complex, seasonally variable system of equatorward and poleward surface and subsurface currents and seasonal upwelling. Not much information exists to ascertain if the modern current and productivity patterns subsisted under glacial climate conditions, such as during marine isotope stage (MIS) 2, and how North Atlantic meltwater events, especially Heinrich events, affected them. To help answer these questions we are combining stable isotope records of surface to subsurface dwelling planktonic foraminifer species with sea surface temperature and export productivity data for four cores distributed along the western... |
| Tipo: Text |
Palavras-chave: Iberian margin; Last Glacial Maximum; Heinrich events; Planktonic foraminifer; Stable isotopes; Productivity. |
| Ano: 2009 |
URL: https://archimer.ifremer.fr/doc/00218/32906/31419.pdf |
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| Lombo Tombo, Swesslath; Dennielou, Bernard; Berne, Serge; Bassetti, Maria-angela; Toucanne, Samuel; Jorry, Stephan; Jouet, Gwenael; Fontanier, Christophe. |
| The timing, routing and processes of sediment transfer from the continents to the oceans at millennial time-scale are still largely unknown. The potential of turbidite systems (dominantly deposited during sea-level lowstands) to record global or regional environmental fluctuations is usually under-exploited because of the difficulty to obtain robust chronostratigraphic constraints in turbiditic deposits, and therefore to tie changes in sedimentary processes to environmental fluctuations. We were able to obtain a millennial-scale chronostratigraphy based on oxygen isotopes of the scarce foraminifera preserved in turbiditic deposits of the Rhone Turbidite System within the Western Mediterranean. Our results show that 1) objective criteria can be defined for... |
| Tipo: Text |
Palavras-chave: Rhone Turbidite System; Turbidites; Hyperpycnite; Sea level; Last Glacial Maximum; Western Mediterranean. |
| Ano: 2015 |
URL: https://archimer.ifremer.fr/doc/00266/37712/35730.pdf |
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| Rogerson, M.; Colmenero-hidalgo, E.; Levine, R. C.; Rohling, E. J.; Voelker, A. H. L.; Bigg, G. R.; Schoenfeld, J.; Cacho, I.; Sierro, F. J.; Lowemark, L.; Reguera, M. I.; De Abreu, L.; Garrick, K.. |
| The Atlantic-Mediterranean exchange of water at Gibraltar represents a significant heat and freshwater sink for the North Atlantic and is a major control on the heat, salt and freshwater budgets of the Mediterranean Sea. Consequently, an understanding of the response of the exchange system to external changes is vital to a full comprehension of the hydrographic responses in both ocean basins. Here, we use a synthesis of empirical (oxygen isotope, planktonic foraminiferal assemblage) and modeling (analytical and general circulation) approaches to investigate the response of the Gibraltar Exchange system to Atlantic freshening during Heinrich Stadials (HSs). HSs display relatively flat W-E surface hydrographic gradients more comparable to the Late Holocene... |
| Tipo: Text |
Palavras-chave: Atlantic; Mediterranean; Gibraltar; Heinrich Event; Last Glacial Maximum; Mediterranean Outflow. |
| Ano: 2010 |
URL: https://archimer.ifremer.fr/doc/00231/34189/32775.pdf |
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| Bian, Yeping; Jian, Zhimin; Weng, Chengyu; Kuhnt, Wolfgang; Bolliet, Timothe; Holbourn, Ann. |
| A palynological analysis of a marine sediment core in the southern Philippines, provides a detailed regional vegetation and climate history for the West Pacific Warm Pool (WPWP) since the Last Glacial Maximum (LGM). Chronology was determined by a detailed oxygen isotope record. A higher representation of pollen from tropical upper montane rainforest during the LGM indicate that this forest type moved down along elevation, probabaly due to the lowered temperature. During the last deglaciation and the early Holocene, mangroves were more expanded and tropical mid and upper montane rainforests were restricted, suggesting a rising sea-level and temperature increase. Herbaceous pollen and pteridophyte spore records indicate a much drier condition during the LGM... |
| Tipo: Text |
Palavras-chave: Last Glacial Maximum; Tropical rainforests; Palynological analyses; Sea-level change; River discharge. |
| Ano: 2011 |
URL: https://archimer.ifremer.fr/doc/00213/32468/30921.pdf |
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| Meireles,Leonardo Dias; Shepherd,George John. |
| The upper montane forests in the southern and southeastern regions of Brazil have an unusual and discontinuous geographic distribution at the top of the Atlantic coastal mountain ranges. To describe the floristic composition and structure of the Atlantic Forest near its upper altitudinal limit in southeastern Brazil, 30 plots with 10 × 10 m were installed in three forest sites between 2,200 and 2,300 m.a.s.l. at Serra Fina. The floristic composition and phytosociological structure of this forest were compared with other montane and upper montane forests. In total, 704 individuals were included, belonging to 24 species, 15 families, and 19 genera. Myrsinaceae, Myrtaceae, Symplocaceae, and Cunoniaceae were the most important families, and Myrsine... |
| Tipo: Info:eu-repo/semantics/article |
Palavras-chave: Atlantic Rain Forest; Cloud forest; Last Glacial Maximum; Mantiqueira mountain range; Montane forest. |
| Ano: 2015 |
URL: http://www.scielo.br/scielo.php?script=sci_arttext&pid=S0102-33062015000100058 |
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| Registros recuperados: 21 | |
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