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| Howe, Jacob N. W.; Piotrowski, Alexander M.; Noble, Taryn L.; Mulitza, Stefan; Chiessi, Cristiano M.; Bayon, Germain. |
| Changes in deep ocean ventilation are commonly invoked as the primary cause of lower glacial atmospheric CO2. The water mass structure of the glacial deep Atlantic Ocean and the mechanism by which it may have sequestered carbon remain elusive. Here we present neodymium isotope measurements from cores throughout the Atlantic that reveal glacial-interglacial changes in water mass distributions. These results demonstrate the sustained production of North Atlantic Deep Water under glacial conditions, indicating that southern-sourced waters were not as spatially extensive during the Last Glacial Maximum as previously believed. We demonstrate that the depleted glacial delta C-13 values in the deep Atlantic Ocean cannot be explained solely by water mass source... |
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| Ano: 2016 |
URL: http://archimer.ifremer.fr/doc/00343/45386/44888.pdf |
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| Govin, Aline; Holzwarth, Ulrike; Heslop, David; Keeling, Lara Ford; Zabel, Matthias; Mulitza, Stefan; Collins, James A.; Chiessi, Cristiano M.. |
| Numerous studies use major element concentrations measured on continental margin sediments to reconstruct terrestrial climate variations. The choice and interpretation of climate proxies however differ from site to site. Here we map the concentrations of major elements (Ca, Fe, Al, Si, Ti, K) in Atlantic surface sediments (36 degrees N-49 degrees S) to assess the factors influencing the geochemistry of Atlantic hemipelagic sediments and the potential of elemental ratios to reconstruct different terrestrial climate regimes. High concentrations of terrigenous elements and low Ca concentrations along the African and South American margins reflect the dominance of terrigenous input in these regions. Single element concentrations and elemental ratios including... |
| Tipo: Text |
Palavras-chave: Atlantic surface sediments; Terrigenous input; Major elements. |
| Ano: 2012 |
URL: https://archimer.ifremer.fr/doc/00214/32550/31035.pdf |
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| Campos, Marilia C.; Chiessi, Cristiano M.; Voigt, Ines; Piola, Alberto R.; Kuhnert, Henning; Mulitza, Stefan. |
| Abrupt millennial-scale climate change events of the last deglaciation (i.e. Heinrich Stadial 1 and the Younger Dryas) were accompanied by marked increases in atmospheric CO2 (CO2atm) and decreases in its stable carbon isotopic ratios (delta C-13), i.e. delta(CO2atm)-C-13, presumably due to out-gassing from the ocean. However, information on the preceding Heinrich Stadials during the last glacial period is scarce. Here we present delta C-13 records from two species of planktonic foraminifera from the western South Atlantic that reveal major decreases (up to 1%) during Heinrich Stadials 3 and 2. These delta C-13 decreases are most likely related to millennial-scale periods of weakening of the Atlantic meridional overturning circulation and the consequent... |
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| Ano: 2017 |
URL: https://archimer.ifremer.fr/doc/00420/53162/55294.pdf |
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