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| Registros recuperados: 16 | |
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| Mahiques,Michel M.; Sousa,Silvia H.M.; Burone,Leticia; Nagai,Renata H.; Silveira,Ilson C.A.; Figueira,Rubens C.L.; Soutelino,Rafael G.; Ponsoni,Leandro; Klein,Daniel A.. |
| The aim of this work was to generate an inventory of the data on radiocarbon datings obtained from sediments of the São Paulo Bight (southern Brazilian upper margin) and to analyze the data in terms of Late Quaternary sedimentary processes and sedimentation rates. A total of 238 radiocarbon datings from materials collected using differents ampling procedures was considered for this work. The sedimentation rates varied from less than 2 to 68 cm.kyr-1. The highest sedimentation rate values were found in a low-energy (ría type) coastal system as well as in the upwelling zones of Santa Catarina and Cabo Frio. The lowest rates were found on the outer shelf and upper slopes. Our results confirm the strong dependency of the shelf currents, with an emphasis to the... |
| Tipo: Info:eu-repo/semantics/article |
Palavras-chave: Continental margin; Quaternary; Radiocarbon; Sea-level; Sedimentation. |
| Ano: 2011 |
URL: http://www.scielo.br/scielo.php?script=sci_arttext&pid=S0001-37652011000300006 |
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| Ronge, Thomas A.; Prange, M.; Mollenhauer, Gesine; Ellinghausen, Maret; Kuhn, G.; Tiedemann, R.. |
| It is widely assumed that the ventilation of the Southern Ocean played a crucial role in driving glacial‐interglacial atmospheric CO2‐levels. So far however, ventilation records from the Indian sector of the Southern Ocean, are widely missing. Here we present reconstructions of water residence times (depicted as ΔΔ14C and Δδ13C) for the last 32,000 years on sediment records from the Kerguelen Plateau and the Conrad Rise (~570‐2500 m water depth), along with simulated changes in ocean stratification from a transient climate model experiment. Our data indicate that Circumpolar Deep Waters in the Indian Ocean were part of the glacial carbon pool. At our sites, close to or bathed by upwelling deep‐waters, we find two pulses of decreasing ΔΔ14C and δ13C values... |
| Tipo: Text |
Palavras-chave: Radiocarbon; Ventilation; Southern Ocean; Younger Dryas; Carbon cycle; Indian Ocean. |
| Ano: 2020 |
URL: https://archimer.ifremer.fr/doc/00611/72351/71258.pdf |
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| Blamer, Sven. |
| The 14C reservoir age of ocean surface waters shows small-scale spatial and temporal variations. Accordingly, correct estimates of reservoir ages are crucial for any reconstruction of a precise radiocarbon-based chronology of marine sediments. To meet this target in the mid- and low- latitude Atlantic we obtained both 14C reservoir ages and an absolute age model for the glacial-to-deglacial sections of four marine sediment cores by means of the ‘14C Plateau Tuning Technique’. This method is independent of any common conversion scheme of 14C ages. The resulting empiric reservoir ages were compared with reservoir age estimates based on model simulations. |
| Tipo: Text |
Palavras-chave: Reservoir ages; Deep water ventilation ages; Atlantic; Radiocarbon. |
| Ano: 2016 |
URL: https://archimer.ifremer.fr/doc/00493/60445/63890.pdf |
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| Stern, Joseph V.; Lisiecki, Lorraine E.. |
| Benthic O-18 changes are often assumed to be globally synchronous, but studies comparing 2-9 radiocarbon-dated records over the most recent deglaciation (Termination 1) have proposed differences in the timing of benthic O-18 change between the Atlantic and Pacific, intermediate and deep, and North and South Atlantic. Because of the relatively small number of records used in these previous studies, it has remained unclear whether these differences are local or regional in scale. Here we present seven regional benthic O-18 stacks for 0-40 kyr B.P. that include 252 records with independent regional age models constrained by 852 planktonic foraminiferal C-14 dates from 61 of these cores. We find a 4000 year difference between the earliest termination onset in... |
| Tipo: Text |
Palavras-chave: Termination 1; Regional stacks; Benthic delta O-18; Radiocarbon. |
| Ano: 2014 |
URL: https://archimer.ifremer.fr/doc/00289/40039/38763.pdf |
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| Lindsay, Colin M.; Lehman, Scott J.; Marchitto, Thomas M.; Carriquiry, Jose D.; Ortiz, Joseph D.. |
| Previous studies have shown that radiocarbon activities (C-14) in the low-latitude, middepth Pacific and Indian Oceans were anomalously low during Heinrich Stadial 1 (HS1, similar to 17.8-14.6ka) and the Younger Dryas (YD, similar to 12.8-11.5ka), coincident with intervals of rising atmospheric CO2 concentration and declining atmospheric C-14. However, a full explanation of these events remains elusive due to sparse and sometimes conflicting data. Here we present new C-14 measurements on benthic and planktic foraminifera that, in combination with previously published measurements, enable us to reconstruct the C-14 depth gradient near Baja California. Vertical profiles were similar to present during the Last Glacial Maximum and BOlling/Allerod (14.6-12.8ka)... |
| Tipo: Text |
Palavras-chave: Radiocarbon; Deglaciation; Heinrich Stadial 1; Baja California; Benthic foraminifera. |
| Ano: 2016 |
URL: https://archimer.ifremer.fr/doc/00496/60797/64925.pdf |
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| Soulet, Guillaume; Menot, Guillemette; Garreta, Vincent; Rostek, Frauke; Zaragosi, Sebastien; Lericolais, Gilles; Bard, Edouard. |
| Chronologies of sediments that document the last glacial history of the Black Sea "Lake" are hampered by issues relating to reservoir age. Regulated by basin hydrology, reservoir ages represent a tool that could potentially be used to better understand the response of Black Sea "Lake" hydrology to climate change. Therefore, deciphering reservoir age evolution is crucial both for better constraining the basin chronological framework and for providing new insights into our understanding of Black Sea "Lake" hydrology. By tuning a meaningful new high-resolution geochemical dataset (obtained from core MD04-2790) to a climate reference record, here, we propose a reliable chronology spanning the last 32 kyr BP. The chronology is compared to a large AMS... |
| Tipo: Text |
Palavras-chave: Black Sea; Reservoir age; Radiocarbon; Last Glacial; Last Deglaciation; Paleoclimate. |
| Ano: 2011 |
URL: http://archimer.ifremer.fr/doc/00043/15379/12817.pdf |
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| Skinner, L. C.; Freeman, E.; Hodell, D.; Waelbroeck, C.; Vazquez Riveiros, Natalia; Scrivner, A.e. |
| Changes in ocean ventilation, controlled by both overturning rates and air‐sea gas exchange, are thought to have played a central role in atmospheric CO2 rise across the last deglaciation. Here we constrain the nature of Atlantic Ocean ventilation changes over the last deglaciation using radiocarbon and stable carbon isotopes from two depth transects in the Atlantic basin. Our findings broadly cohere with the established pattern of deglacial Atlantic overturning change, and underline the existence of active northern sourced deep‐water export at the Last Glacial Maximum (LGM). We find that the western Atlantic was less affected by incursions of southern‐sourced deep water, as compared to the eastern Atlantic, despite both sides of the basin being strongly... |
| Tipo: Text |
Palavras-chave: Air‐ Sea exchange; AMOC; Carbon cycle; Deglaciation; Radiocarbon; Ventilation. |
| Ano: 2021 |
URL: https://archimer.ifremer.fr/doc/00665/77717/79810.pdf |
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| Maccali, Jenny; Hillaire-marcel, Claude; Ghaleb, Bassam; Ménabréaz, Lucie; Blénet, Aurélien; Edinger, Evan; Hélie, Jean-françois; Preda, Michel. |
| About 70 fossil and live-collected specimens of Desmophyllum dianthus were collected from steep rocky surfaces and time-averaged assemblages at their base (“coral graveyards”) in the southern Labrador Sea at depths ranging from ~1700 m (Orphan Knoll) to ~2200 m (Flemish Cap). Aside from stable isotope and mineralogical analysis, U-series and 14C age determinations were performed on the samples. Fossil corals from the coral graveyards display two principal age clusters corresponding respectively to the Holocene and Marine Isotope Stage (MIS) 5c intervals. Three samples lay outside these clusters, at ~13.5 ka (Bølling-Allerød), ~ 64 ka (MIS 3) and at ~181 ka (MIS 7a). The clusters are thought to record intervals with both i) high food availability, either... |
| Tipo: Text |
Palavras-chave: Deep-sea corals; Aragonite corals; Labrador Sea; Radiocarbon; U-series dating. |
| Ano: 2020 |
URL: https://archimer.ifremer.fr/doc/00623/73496/72790.pdf |
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| Devries, Tim; Primeau, Francois. |
| Existing methods for inferring the ventilation age of water masses in the ocean using radiocarbon data neglect the effects of diffusive mixing. in the presence of varying atmospheric Delta(14)C, this neglect produces spurious time dependence in the estimated ventilation ages. To correct this deficiency we propose a new method for estimating the ventilation age from sediment core radiocarbon data. The new method is formulated in terms of parameterized age distributions that account for the effects of advective and diffusive transport in the ocean. When applied to simulated radiocarbon data from an OGCM, the method is able to closely reproduce the modeled ventilation age, whereas other methods are not. We also applied the method to sediment-core radiocarbon... |
| Tipo: Text |
Palavras-chave: Ocean Drilling Program; Site 887; Ventilation age; Radiocarbon; Transit-time distribution; Glacial-interglacial. |
| Ano: 2010 |
URL: https://archimer.ifremer.fr/doc/00231/34197/32870.pdf |
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| Skinner, L.; Mccave, I. N.; Carter, L.; Fallon, S.; Scrivner, A. E.; Primeau, F.. |
| It has been proposed that the ventilation of the deep Pacific carbon pool was not significantly reduced during the last glacial period, posing a problem for canonical theories of glacial-interglacial CO2 change. However, using radiocarbon dates of marine tephra deposited off New Zealand, we show that deep(>2000 m) and shallow sub-surface ocean-atmosphere C-14 age offsets (i.e. 'reservoir-' or 'ventilation' ages) in the southwest Pacific increased by similar to 1089 and 337 yrs respectively, reaching similar to 2689 and similar to 1037 yrs during the late glacial. A comparison with other radiocarbon data from the southern high-latitudes suggests that broadly similar changes were experienced right across the Southern Ocean. If, like today, the Southern... |
| Tipo: Text |
Palavras-chave: Radiocarbon; Ocean ventilation; Carbon cycling; Palaeoceanography. |
| Ano: 2015 |
URL: https://archimer.ifremer.fr/doc/00352/46279/46041.pdf |
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| Registros recuperados: 16 | |
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