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| Collins, J. A.; Govin, A.; Mulitza, S.; Heslop, D.; Zabel, M.; Hartmann, J.; Roehl, U.; Wefer, G.. |
| Relict dune fields that are found as far south as 14 N in the modern-day African Sahel are testament to equatorward expansions of the Sahara desert during the Late Pleistocene. However, the discontinuous nature of dune records means that abrupt millennial-timescale climate events are not always resolved. High-resolution marine core studies have identified Heinrich stadials as the dustiest periods of the last glacial in West Africa although the spatial evolution of dust export on millennial timescales has so far not been investigated. We use the major-element composition of four high-resolution marine sediment cores to reconstruct the spatial extent of Saharan-dust versus river-sediment input to the continental margin from West Africa over the last 60 ka.... |
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| Ano: 2013 |
URL: http://archimer.ifremer.fr/doc/00181/29240/27635.pdf |
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| Collins, James A.; Govin, A.; Mulitza, Stefan; Heslop, David; Zabel, M.; Hartmann, J.; Rohl, U.; Wefer, Gerold. |
| Relict dune fields that are found at 14° N in the modern-day African Sahel are testament to equatorward expansions of the Sahara desert during the late Pleistocene. However, difficulties of dating dune formation mean that abrupt millennial-scale climate events are not always resolved in these records. High-resolution marine core studies have identified Heinrich Stadials as the dustiest periods of the last glacial, although no studies have mapped the spatio-temporal evolution of dust export from West Africa. We use the major-element composition of four marine sediment cores to reconstruct the spatial extent of Saharan-dust versus river-sediment input to the continental margin from West Africa over the last 60 ka. This allows us to map the position of the... |
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| Ano: 2013 |
URL: http://archimer.ifremer.fr/doc/00182/29279/27696.pdf |
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| Bouttes, N.; Vazquez Riveiros, Natalia; Govin, A.; Swingedouw, D.; Sanchez-goni, M.f.; Crosta, X.; Roche, D.m.. |
| Ice core data have shown that atmospheric CO2 concentrations during interglacials were lower before the Mid Brunhes Event (MBE, ~430 ka), than after the MBE by around 30 ppm. To explain such a difference, it has been hypothesized that increased bottom water formation around Antarctica or reduced Atlantic Meridional Overturning Circulation (AMOC) could have led to greater oceanic carbon storage before the MBE, resulting in less carbon in the atmosphere. However, only few data on possible changes in interglacial ocean circulation across the MBE have been compiled, hampering model‐data comparison. Here we present a new global compilation of benthic foraminifera carbon isotopic (δ13C) records from 31 marine sediment cores covering the last 800 ka, with the aim... |
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| Ano: 2020 |
URL: https://archimer.ifremer.fr/doc/00619/73130/72285.pdf |
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| Govin, A.; Braconnot, P.; Capron, E.; Cortijo, E.; Duplessy, J. -c.; Jansen, E.; Labeyrie, L.; Landais, A.; Marti, O.; Michel, E.; Mosquet, E.; Risebrobakken, B.; Swingedouw, D.; Waelbroeck, C.. |
| Although the Last Interglacial (LIG) is often considered as a possible analogue for future climate in high latitudes, its precise climate evolution and associated causes remain uncertain. Here we compile high-resolution marine sediment records from the North Atlantic, Labrador Sea, Norwegian Sea and the Southern Ocean. We document a delay in the establishment of peak interglacial conditions in the North Atlantic, Labrador and Norwegian Seas as compared to the Southern Ocean. In particular, we observe a persistent iceberg melting at high northern latitudes at the beginning of the LIG. It is associated with (1) colder and fresher surface-water conditions in the North Atlantic, Labrador and Norwegian Seas, and (2) a weaker ventilation of North Atlantic deep... |
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| Ano: 2012 |
URL: https://archimer.ifremer.fr/doc/00266/37700/35848.pdf |
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| Govin, A.; Capron, E.; Tzedakis, P. C.; Verheyden, S.; Ghaleb, B.; Hillaire-marcel, C.; St-onge, G.; Stoner, J. S.; Bassinot, F.; Bazin, L.; Blunier, T.; Combourieu-nebout, N.; El Ouahabi, A.; Genty, D.; Gersonde, R.; Jimenez-amat, P.; Landais, A.; Martrat, B.; Masson-delmotte, V.; Parrenin, F.; Seidenkrantz, M. -s.; Veres, D.; Waelbroeck, C.; Zahn, R.. |
| The Last Interglacial (LIG) represents an invaluable case study to investigate the response of components of the Earth system to global warming. However, the scarcity of absolute age constraints in most archives leads to extensive use of various stratigraphic alignments to different reference chronologies. This feature sets limitations to the accuracy of the stratigraphic assignment of the climatic sequence of events across the globe during the LIG. Here, we review the strengths and limitations of the methods that are commonly used to date or develop chronologies in various climatic archives for the time span (similar to 140 -100 ka) encompassing the penultimate deglaciation, the LIG and the glacial inception. Climatic hypotheses underlying record... |
| Tipo: Text |
Palavras-chave: Last Interglacial; Penultimate deglaciation; Last glacial inception; Chronology; Corals; Speleothems; Ice cores; Marine sediments; Peat and lake sediments; Climate dynamics. |
| Ano: 2015 |
URL: https://archimer.ifremer.fr/doc/00496/60802/64786.pdf |
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| Govin, A.; Chiessi, C. M.; Zabel, M.; Sawakuchi, A. O.; Heslop, D.; Hoerner, T.; Zhang, Y.; Mulitza, S.. |
| We investigate changes in the delivery and oceanic transport of Amazon sediments related to terrestrial climate variations over the last 250 ka. We present high-resolution geochemical records from four marine sediment cores located between 5 and 12 degrees N along the northern South American margin. The Amazon River is the sole source of terrigenous material for sites at 5 and 9 degrees N, while the core at 12 degrees N receives a mixture of Amazon and Orinoco detrital particles. Using an endmember unmixing model, we estimated the relative proportions of Amazon Andean material ("%-Andes", at 5 and 9 degrees N) and of Amazon material ("%-Amazon", at 12 degrees N) within the terrigenous fraction. The %-Andes and %-Amazon records exhibit significant... |
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| Ano: 2014 |
URL: https://archimer.ifremer.fr/doc/00291/40230/38675.pdf |
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