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| Registros recuperados: 10 | |
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| Cisneros, Merce; Cacho, Isabel; Frigola, Jaime; Canals, Miquel; Masque, Pere; Martrat, Belen; Casado, Marta; Grimalt, Joan O.; Pena, Leopoldo D.; Margaritelli, Giulia; Lirer, Fabrizio. |
| This study presents the reconstructed evolution of sea surface conditions in the central-western Mediterranean Sea during the late Holocene (2700 years) from a set of multi-proxy records as measured on five short sediment cores from two sites north of Minorca (cores MINMC06 and HER-MC-MR3). Sea surface temperatures (SSTs) from alkenones and Globigerina bulloides Mg / Ca ratios are combined with δ18O measurements in order to reconstruct changes in the regional evaporation–precipitation (E–P) balance. We also revisit the G. bulloides Mg / Ca–SST calibration and re-adjusted it based on a set of core-top measurements from the western Mediterranean Sea. Modern regional oceanographic data indicate that Globigerina bulloides Mg / Ca is mainly controlled by... |
| Tipo: Text |
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| Ano: 2016 |
URL: https://archimer.ifremer.fr/doc/00333/44460/44137.pdf |
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| Eynaud, Frederique; De Abreu, Lucia; Voelker, Antje; Schoenfeld, Joachim; Salgueiro, Emilia; Turon, Jean-louis; Penaud, Aurelie; Toucanne, Samuel; Naughton, Filipa; Goni, Maria Fernanda Sanchez; Malaize, Bruno; Cacho, Isabel. |
| This paper documents the migration of the Polar Front (PF) over the Iberian margin during some of the cold climatic extremes of the last 45 ka. It is based on a compilation of robust and coherent paleohydrological proxies obtained from eleven cores distributed between 36 and 42 degrees N. Planktonic delta O-18 (Globigerina bulloides), ice-rafted detritus concentrations, and the relative abundance of the polar foraminifera Neogloboquadrina pachyderma sinistral were used to track the PF position. These three data sets, compared from core to core, show a consistent evolution of the sea surface paleohydrology along the Iberian margin over the last 45 ka. We focused on five time slices representative of cold periods under distinct paleoenvironmental forcings:... |
| Tipo: Text |
Palavras-chave: Polar Front; LGM; Heinrich events. |
| Ano: 2009 |
URL: https://archimer.ifremer.fr/doc/00218/32909/31415.pdf |
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| Kandiano, Evgenia S.; Bauch, Henning A.; Fahl, Kirsten; Helmke, Jan P.; Roehl, Ursula; Perez-folgado, Marta; Cacho, Isabel. |
| Temporal and spatial patterns in eastern North Atlantic sea-surface temperatures (SST) were reconstructed for marine isotope stage (MIS) 11c using a submeridional transect of five sediment cores. The SST reconstructions are based on planktic foraminiferal abundances and alkenone indices, and are supported by benthic and planktic stable isotope measurements, as well as by ice-rafted debris content in polar and middle latitudes. Additionally, the larger-scale dynamics of the precipitation regime over northern Africa and the western Mediterranean region was evaluated from iron concentrations in marine sediments off NW Africa and planktic delta C-13 in combination with analysis of planktic foraminiferal abundances down to the species level in the Mediterranean... |
| Tipo: Text |
Palavras-chave: Eastern North Atlantic; Stage 11; North Atlantic Oscillation; Foraminiferal sea surface temperatures; Alkenone sea surface temperatures. |
| Ano: 2012 |
URL: https://archimer.ifremer.fr/doc/00265/37654/36976.pdf |
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| 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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| Rippert, Nadine; Max, Lars; Mackensen, Andreas; Cacho, Isabel; Povea, Patricia; Tiedemann, Ralf. |
| The eastern equatorial Pacific (EEP) is a key area to understand past oceanic processes that control atmospheric CO2 concentrations. Many studies argue for higher nutrient concentrations by enhanced nutrient transfer via Southern Ocean Intermediate Water (SOIW) to the low-latitude Pacific during glacials. Recent studies, however, argue against SOIW as the primary nutrient source, at least during early Marine Isotope Stage 2 (MIS 2), as proxy data indicate that nutrients are better utilized in the Southern Ocean under glacial conditions. New results from the subarctic Pacific suggest that enhanced convection of nutrient-rich Glacial North Pacific Intermediate Water (GNPIW) contributes to changes in nutrient concentrations in equatorial subthermocline water... |
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| Ano: 2017 |
URL: https://archimer.ifremer.fr/doc/00497/60825/64592.pdf |
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| Cacho, Isabel; Grimalt, Joan O.; Pelejero, Carles; Canals, Miquel; Sierro, Francisco; Flores, Jose Abel; Shackleton, Nicholas J.. |
| Past sea surface temperature (SST) evolution in the Alboran Sea (western Mediterranean) during the last 50,000 years has been inferred from the study of C-37 alkenones in International Marine Global Change Studies MD952043 core. This record has a time resolution of similar to 200 years allowing the study of millennial-scale and even shorter climatic changes. The observed SST curve displays characteristic sequences of extremely rapid warming and cooling events along the glacial period. Comparison of this Alboran record with delta(18)O from Greenland ice (Greenland Ice Sheet Project 2 core) shows a strong parallelism between these SST oscillations and the Dansgaard-Oeschger events. Five prominent cooling episodes standing out in the SST profile are... |
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| Ano: 1999 |
URL: https://archimer.ifremer.fr/doc/00239/35044/36810.pdf |
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| 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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| Martinez-mendez, Gema; Zahn, Rainer; Hall, Ian R.; Peeters, Frank J. C.; Pena, Leopoldo D.; Cacho, Isabel; Negre, Cesar. |
| Planktonic delta(18)O and Mg/Ca-derived sea surface temperature (SST) records from the Agulhas Corridor off South Africa display a progressive increase of SST during glacial periods of the last three climatic cycles. The SST increases of up to 4 degrees C coincide with increased abundance of subtropical planktonic foraminiferal marker species which indicates a progressive warming due to an increased influence of subtropical waters at the core sites. Mg/Ca-derived SST maximizes during glacial maxima and glacial Terminations to values about 2.5 degrees C above full-interglacial SST. The paired planktonic delta(18)O and Mg/Ca-derived SST records yield glacial seawater delta(18)O anomalies of up to 0.8%, indicating measurably higher surface salinities during... |
| Tipo: Text |
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| Ano: 2010 |
URL: https://archimer.ifremer.fr/doc/00230/34134/32779.pdf |
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| Registros recuperados: 10 | |
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