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Response of Iberian Margin sediments to orbital and suborbital forcing over the past 420 ka 5
Hodell, David; Crowhurst, Simon; Skinner, Luke; Tzedakis, Polychronis C.; Margari, Vasiliki; Channell, James E. T.; Kamenov, George; Maclachlan, Suzanne; Rothwell, Guy.
Here we report 420 kyr long records of sediment geochemical and color variations from the southwestern Iberian Margin. We synchronized the Iberian Margin sediment record to Antarctic ice cores and speleothem records on millennial time scales and investigated the phase responses relative to orbital forcing of multiple proxy records available from these cores. Iberian Margin sediments contain strong precession power. Sediment "redness" (a* and 570-560 nm) and the ratio of long-chain alcohols to n-alkanes (C26OH/(C26OH+C-29)) are highly coherent and in-phase with precession. Redder layers and more oxidizing conditions (low alcohol ratio) occur near precession minima (summer insolation maxima). We suggest these proxies respond rapidly to low-latitude...
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Ano: 2013 URL: https://archimer.ifremer.fr/doc/00262/37304/35702.pdf
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The Evolution of Deep Ocean Chemistry and Respired Carbon in the Eastern Equatorial Pacific Over the Last Deglaciation 5
De La Fuente, Maria; Calvo, Eva; Skinner, Luke; Pelejero, Carles; Evans, David; Mueller, Wolfgang; Povea, Patricia; Cacho, Isabel.
It has been shown that the deep Eastern Equatorial Pacific (EEP) region was poorly ventilated during the Last Glacial Maximum (LGM) relative to Holocene values. This finding suggests a more efficient biological pump, which indirectly supports the idea of increased carbon storage in the deep ocean contributing to lower atmospheric CO2 during the last glacial. However, proxies related to respired carbon are needed in order to directly test this proposition. Here we present Cibicides wuellerstorfi B/Ca ratios from Ocean Drilling Program Site 1240 measured by laser ablation inductively coupled plasma mass spectrometry (LA-ICPMS) as a proxy for deep water carbonate saturation state ([CO32-], and therefore [CO32-]), along with C-13 measurements. In addition, the...
Tipo: Text Palavras-chave: Marine carbon cycle; Carbonate chemistry; Ocean circulation; Glacial-interglacial cycles; Soft-tissue pump efficiency; Seafloor calcite dissolution.
Ano: 2017 URL: https://archimer.ifremer.fr/doc/00497/60824/64598.pdf
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Increased reservoir ages and poorly ventilated deep waters inferred in the glacial Eastern Equatorial Pacific 5
De La Fuente, Maria; Skinner, Luke; Calvo, Eva; Pelejero, Carles; Cacho, Isabel.
Consistent evidence for a poorly ventilated deep Pacific Ocean that could have released its radiocarbon-depleted carbon stock to the atmosphere during the last deglaciation has long been sought. Such evidence remains lacking, in part due to a paucity of surface reservoir age reconstructions required for accurate deep-ocean ventilation age estimates. Here we combine new radiocarbon data from the Eastern Equatorial Pacific (EEP) with chronostratigraphic calendar age constraints to estimate shallow sub-surface reservoir age variability, and thus provide estimates of deep-ocean ventilation ages. Both shallow- and deep-water ventilation ages drop across the last deglaciation, consistent with similar reconstructions from the South Pacific and Southern Ocean. The...
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Ano: 2015 URL: https://archimer.ifremer.fr/doc/00351/46257/46070.pdf
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