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| Maria Mejia, Luz; Ziveri, Patrizia; Cagnetti, Marilisa; Bolton, Clara; Zahn, Rainer; Marino, Gianluca; Martinez-mendez, Gema; Stoll, Heather. |
| Modern primary productivity on the Agulhas Bank, off South Africa, has been proposed to be linked to the midlatitude westerlies. A paleoproductivity record from this area may therefore resolve temporal changes in the westerly dynamics. Accordingly, we produced a coccolith Sr/Ca-based paleoproductivity record from core MD96-2080 (Agulhas Bank slope) during the penultimate glacial-interglacial cycle. Deriving the productivity signal from Sr/Ca requires a correction for a temperature effect, here constrained using Mg/Ca sea surface temperatures from the foraminifer Globigerina bulloides from core MD96-2080. Phases of depressed productivity coincided with periods of stratification in the same core, indicated by high relative abundances of the coccolithophore... |
| Tipo: Text |
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| Ano: 2014 |
URL: https://archimer.ifremer.fr/doc/00290/40116/39135.pdf |
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| Marino, Gianluca; Zahn, Rainer; Ziegler, Martin; Purcell, Conor; Knorr, Gregor; Hall, Ian R.; Ziveri, Patrizia; Elderfield, Henry. |
| An ensemble of new, high-resolution records of surface ocean hydrography from the Indian-Atlantic oceanic gateway, south of Africa, demonstrates recurrent and high-amplitude salinity oscillations in the Agulhas Leakage area during the penultimate glacial-interglacial cycle. A series of millennial-scale salinification events, indicating strengthened salt leakage into the South Atlantic, appear to correlate with abrupt changes in the North Atlantic climate and Atlantic Meridional Overturning Circulation (AMOC). This interhemispheric coupling, which plausibly involved changes in the Hadley Cell and midlatitude westerlies that impacted the interocean transport at the tip of Africa, suggests that the Agulhas Leakage acted as a source of negative buoyancy for... |
| Tipo: Text |
Palavras-chave: Agulhas Leakage; Abrupt climate change; Millennial-scale variability; AMOC; Bipolar seesaw; Southern Hemisphere atmospheric circulation. |
| Ano: 2013 |
URL: https://archimer.ifremer.fr/doc/00264/37493/35791.pdf |
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| Grelaud, Michael; Marino, Gianluca; Ziveri, Patrizia; Rohling, Eelco J.. |
| A detailed assessment of the respective roles of production, export, and subsequent preservation of organic carbon (C-org) in the eastern Mediterranean (EMED) sediments during the formation of sapropels remains elusive. Here we present new micropaleontological results for both surface samples taken at several locations in the EMED and last interglacial sapropel S5 from core LC21 in the southeastern Aegean Sea. A strong exponential anticorrelation between relative abundances of the lower photic zone coccolithophore Florisphaera profunda in the surface sediments and modern concentrations of chlorophyll a (Chl-a) at the sea surface suggests that F. profunda percentages can be used to track past productivity changes in the EMED. Prior to S5 deposition, an... |
| Tipo: Text |
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| Ano: 2012 |
URL: https://archimer.ifremer.fr/doc/00265/37632/36756.pdf |
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