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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... |
| Tipo: Text |
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| Ano: 2016 |
URL: http://archimer.ifremer.fr/doc/00343/45386/44888.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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| Tachikawa, Kazuyo; Arsouze, Thomas; Bayon, Germain; Bory, Aloys; Colin, Christophe; Dutay, Jean-claude; Frank, Norbert; Giraud, Xavier; Gourlan, Alexandra T.; Jeandel, Catherine; Lacan, Francois; Meynadier, Laure; Montagna, Paolo; Piotrowski, Alexander M.; Plancherel, Yves; Puceat, Emmanuelle; Roy-barman, Matthieu; Waelbroeck, Claire. |
| Neodymium isotopic compositions (143Nd/144Nd or εNd) have been used as a tracer of water masses and lithogenic inputs to the ocean. To further evaluate the faithfulness of this tracer, we have updated a global seawater εNd database and combined it with hydrography parameters (temperature, salinity, nutrients and oxygen concentrations), carbon isotopic ratio and radiocarbon of dissolved inorganic carbon. Archive εNd data are also compiled for leachates, foraminiferal tests, deep-sea corals and fish teeth/debris from the Holocene period (< 10,000 years). At water depths ≥ 1500 m, property-property plots show clear correlations between seawater εNd and the other variables, suggesting that large-scale water mass mixing is a primary control of deepwater εNd... |
| Tipo: Text |
Palavras-chave: Nd isotopes; Water mass tracer; Data compilation; Predicted seawater epsilon(Nd); Seawater-archive comparison. |
| Ano: 2017 |
URL: http://archimer.ifremer.fr/doc/00376/48768/49165.pdf |
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| Major, Candace O.; Goldstein, Steven L.; Ryan, William B.f.; Lericolais, Gilles; Piotrowski, Alexander M.; Hajdas, Irka. |
| The Black Sea was an inland lake during the last ice age and its sediments are an excellent potential source of information on Eurasian climate change, showing linkages between regionally and globally recognized millennial-scale climate events of the last deglaciation. Here, we detail changes from the last glacial maximum (LGM) through the transition to an anoxic marginal sea using isotopic (strontium and oxygen) and trace element (Sr/Ca) ratios in carbonate shells, which record changing input sources and hydrologic conditions in the basin and surrounding region. Sr isotope records show two prominent peaks between similar to 18 and 16 ka BP cal, reflecting anomalous sedimentation associated with meltwater from disintegrating Eurasian ice sheets that... |
| Tipo: Text |
Palavras-chave: Sea level changes; Black Sea; Deglaciation; Glaciation; Palaeoclimate; Palaeoceanography. |
| Ano: 2006 |
URL: http://archimer.ifremer.fr/doc/2006/publication-2006.pdf |
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