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| Registros recuperados: 49 | |
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| Chen, Yy; Chen, Mt; Fang, Ts. |
| Ultrahigh resolution records of carbonate and organic carbon concentrations from core MD972148 (19 degrees 47.804'N 117 degrees 32.56'E; water depth 2830 m) provide information on glacial-interglacial as well as millennial to centennial scale variability in the production of biogenic sediments in the northern slope of the South China Sea (SCS) over the past 150,000 years. A preliminary age model of this record is estimated using a biostratigraphic datum of Globigerinoides ruber (pink) and the relationship of carbonate concentrations and partial derivative(18)O of planktonic foraminifers shown in previous SCS records. The downcore patterns in this record show that the carbonate concentration maxima correspond to interglacial times and minima correspond to... |
| Tipo: Text |
Palavras-chave: Paleoceanography; Late Quaternary; Carbonate sedimentology; South China Sea. |
| Ano: 1999 |
URL: https://archimer.ifremer.fr/doc/00239/35072/34559.pdf |
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| Freslon, Nicolas; Bayon, Germain; Toucanne, Samuel; Bermell, Sylvain; Bollinger, Claire; Chéron, Sandrine; Etoubleau, Joel; Germain, Yoan; Khripounoff, Alexis; Ponzevera, Emmanuel; Rouget, Marie Laure. |
| We report rare earth element (REE) and neodymium (Nd) isotope data for the organic fraction of sediments collected from various depositional environments, i.e. rivers (n=25), estuaries (n=18), open-ocean settings (n=15), and cold seeps (n=12). Sedimentary Organic Matter (SOM) was extracted using a mixed hydrogen peroxide/nitric acid solution (20%-H2O2 – 0.02M-HNO3), after removal of carbonate and oxy-hydroxide phases with dilute hydrochloric acid (0.25M-HCl). A series of experimental tests indicate that extraction of sedimentary organic compounds using H202 may be complicated occasionally by partial dissolution of sulphide minerals and residual carbonates. However, this contamination is expected to be minor for REE because measured concentrations in H2O2... |
| Tipo: Text |
Palavras-chave: Organic matter; Rare earth elements; REE; Neodymium isotopes; ΕNd; Sediment; Boundary Exchange; Paleoceanography. |
| Ano: 2014 |
URL: http://archimer.ifremer.fr/doc/00191/30250/28682.pdf |
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| Rabouille, C.; Dennielou, Bernard; Baudin, F.; Raimonet, M.; Droz, Laurence; Khripounoff, Alexis; Martinez, P.; Mejanelle, L.; Michalopoulos, P.; Pastor, Lucie; Pruski, A.; Ragueneau, Olivier; Reyss, J.-l.; Ruffine, Livio; Schnyder, J.; Stetten, E.; Taillefert, M.; Tourolle, Julie; Olu, Karine. |
| Carbon and silicon cycles at the Earth surface are linked to long-term variations of atmospheric CO2 and oceanic primary production. In these cycles, the river-sea interface is considered a biogeochemical hotspot, and deltas presently receive and preserve a major fraction of riverine particles in shallow water sediments. In contrast, periods of glacial maximum lowstand were characterized by massive exports of sediments to the deep-sea via submarine canyons and accumulation in deep-sea fans. Here, we calculate present-day mass balances for organic carbon (OC) and amorphous silica (aSi) in the terminal lobe complex of the Congo River deep-sea fan as an analogue for glacial periods. We show that this lobe complex constitutes a megasink with the current... |
| Tipo: Text |
Palavras-chave: Present; Paleoceanography; South Atlantic; Inorganic geochemistry; Organic geochemistry; Sedimentology-marine cores. |
| Ano: 2019 |
URL: https://archimer.ifremer.fr/doc/00511/62289/66720.pdf |
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| Rasmussen, Tine L.; Thomsen, Erik. |
| The last deglaciation, 20,000–10,000 years ago, was a period of global warming and rapidly shrinking ice sheets. It was also climatically unstable and retreats were interrupted by re-advances. Retreat rates and timing relative to climatic changes have therefore been difficult to establish. We here study a suite of 12 marine sediment cores from Storfjorden and Storfjorden Trough, Svalbard. The purpose is to reconstruct retreat patterns and retreat rates of a high northern latitude marine-based ice stream from the Svalbard-Barents Sea Ice Sheet in relation to paleoceanographic and paleoclimatic changes. The study is based on abundance and composition of planktic and benthic foraminiferal assemblages, ice rafted debris (IRD), lithology, and 70 AMS-14C dates.... |
| Tipo: Text |
Palavras-chave: Ice retreat rates; Storfjorden ice stream; Paleoceanography; Paleoclimate; Paleotemperature. |
| Ano: 2021 |
URL: https://archimer.ifremer.fr/doc/00658/77019/78289.pdf |
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| Zhao, Xueqin. |
| South Africa is very sensitive to climate change, because it is located between two atmospheric systems (subtropical and warm-temperate systems) and two oceanic systems (Benguela Current and Agulhas Current). Presently, the seasonal changes of atmospheric and oceanic systems induce a pronounced rainfall seasonality comprised of three different rainfall zones (summer rainfall zone, SRZ; year-round rainfall zone, YRZ and winter rainfall zone, WRZ) over South Africa. However, the seasonality development during the Holocene in South Africa is poorly understood and the driving forces of the climate change are debated. Therefore, this study aims to provide a detailed reconstruction of Holocene climate and vegetation variability of South Africa,... |
| Tipo: Text |
Palavras-chave: Holocene; Marine sediments; Pollen; Microcharcoal; Organic-walled dinoflagellate cyst; Paleoenvironment; Paleoceanography; South Africa. |
| Ano: 2017 |
URL: https://archimer.ifremer.fr/doc/00493/60442/63887.pdf |
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| Marcott, Shaun A.; Clark, Peter U.; Padman, Laurie; Klinkhammer, Gary P.; Springer, Scott R.; Liu, Zhengyu; Otto-bliesner, Bette L.; Carlson, Anders E.; Ungerer, Andy; Padman, June; He, Feng; Cheng, Jun; Schmittner, Andreas. |
| Episodic iceberg-discharge events from the Hudson Strait Ice Stream (HSIS) of the Laurentide Ice Sheet, referred to as Heinrich events, are commonly attributed to internal ice-sheet instabilities, but their systematic occurrence at the culmination of a large reduction in the Atlantic meridional overturning circulation (AMOC) indicates a climate control. We report Mg/Ca data on benthic foraminifera from an intermediate-depth site in the northwest Atlantic and results from a climate-model simulation that reveal basin-wide subsurface warming at the same time as large reductions in the AMOC, with temperature increasing by approximately 2 C over a 1-2 kyr interval prior to a Heinrich event. In simulations with an ocean model coupled to a thermodynamically... |
| Tipo: Text |
Palavras-chave: Paleoceanography; Paleoclimatology; Abrupt climate change. |
| Ano: 2011 |
URL: https://archimer.ifremer.fr/doc/00227/33819/32479.pdf |
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| Rasmussen, Tl; Oppo, Dw; Thomsen, E; Lehman, Sj. |
| [1] Results from two deep sea cores from northeast of Newfoundland at 1251 and 2527 m water depth, respectively, indicate that during the time period from 160,000 to 10,000 years BP, ice rafting events in the Labrador Sea were accompanied by rapid variations in deep and surface water circulation. Twelve ice-rafting events occurred, each coinciding with high concentrations of detrital carbonate and oxygen isotopic depletion of both surface and bottom waters. Eleven of these can be correlated with the North Atlantic Heinrich events H1-H11. The remaining very conspicuous ice-rafting event took place early in MIS substage 5e, at a time when the planktic faunal assemblage suggests marked warming of the sea surface. In the shallower core, benthic delta(13)C... |
| Tipo: Text |
Palavras-chave: Paleoceanography; Labrador Sea; Ice rafting; Foraminifera; Last climate cycle. |
| Ano: 2003 |
URL: https://archimer.ifremer.fr/doc/00496/60768/65083.pdf |
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| Berben, Sarah M.p.; Dokken, Trond M.; Abbott, Peter M.; Cook, Eliza; Sadatzki, Henrik; Simon, Margit H; Jansen, Eystein. |
| Understanding the dynamics that drove past abrupt climate changes, such as the Dansgaard-Oeschger (DO) events, depends on combined proxy evidence from disparate archives. To identify leads, lags and synchronicity between different climate system components, independent and robust chronologies are required. Cryptotephrochronology is a key geochronological tool as cryptotephra horizons can act as isochrons linking disparate and/or distant records. Here, we investigated marine sediment core MD99-2284 from the Norwegian Sea to look for previously identified Greenland ice core cryptotephra horizons and define time-parallel markers between the archives. We explored potential secondary transport and depositional mechanisms that could hamper the isochronous... |
| Tipo: Text |
Palavras-chave: Quaternary; Paleoclimatology; Paleoceanography; North Atlantic; Sedimentology; Marine cores; Ice cores; Cryptotephrochronology; DO-Events; Synchronization. |
| Ano: 2020 |
URL: https://archimer.ifremer.fr/doc/00622/73391/72606.pdf |
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| Charles, Claire; Pelleter, Ewan; Révillon, Sidonie; Nonnotte, Philippe; Jorry, Stephan; Kluska, Jean-michel. |
| The Mozambique Channel plays a key role in the exchange of water masses between the Indian and Atlantic Oceans, which include the North Atlantic Deep Water (NADW) inflow from the south and the North Indian Deep Water (NIDW), an aged form of the NADW spreading poleward from the northern and equatorial Indian Ocean basin. Several authors assume that the Davie Ridge acts as a topographic barrier to the northward advection of NADW, which would therefore be absent in the Comoros Basin. Other studies suggest that the NADW flows from the south of the Mozambique Channel to the Comoros Basin, indicating that the Davie Ridge may not currently constitute a blocking topographic barrier to deep water mass circulation. To address this question, we studied ferromanganese... |
| Tipo: Text |
Palavras-chave: Ferromanganese crusts; Nd isotopes; Paleoceanography; Mozambique Channel; North Atlantic Deep Water. |
| Ano: 2020 |
URL: https://archimer.ifremer.fr/doc/00653/76488/77569.pdf |
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| Kissel, Catherine; Laj, Carlo; Kienast, Markus; Bolliet, Timothe; Holbourn, Ann; Hill, Paul; Kuhnt, Wolfgang; Braconnot, Pascale. |
| Magnetic and grain size properties of a sediment core located in the western equatorial Pacific, off the southeastern tip of the Philippine island of Mindanao, are presented in an effort to reconstruct past changes in the East Asian Monsoon and deep ocean circulation during the last 160 kyrs. The sedimentary concentration of magnetic particles, interpreted to reflect past changes in runoff from Mindanao, varies almost in antiphase with Northern Hemisphere insolation. This suggests that precipitation was lower in the western equatorial Pacific region during boreal insolation maxima and thus corroborates model results showing opposing trends in precipitation between land and the marine realm there. Variations in the grain size distribution of the inorganic... |
| Tipo: Text |
Palavras-chave: North atlantic; Grain size; Water; Core; Mindanao; Paleoceanography; Susceptibility; Anisotropy; Remanence; Iceland. |
| Ano: 2010 |
URL: https://archimer.ifremer.fr/doc/00207/31854/30262.pdf |
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| Lamy, Frank; Arz, Helge W.; Kilianc, Rolf; Lange, Carina B.; Lembke-jene, Lester; Wengler, Marc; Kaiser, Jerome; Baeza-urrea, Oscar; Hall, Ian R.; Harada, Naomi; Tiedemann, Ralf. |
| The Drake Passage (DP) is the major geographic constriction for the Antarctic Circumpolar Current (ACC) and exerts a strong control on the exchange of physical, chemical, and biological properties between the Atlantic, Pacific, and Indian Ocean basins. Resolving changes in the flow of circumpolar water masses through this gateway is, therefore, crucial for advancing our understanding of the Southern Ocean's role in global ocean and climate variability. Here, we reconstruct changes in DP throughflow dynamics over the past 65,000 y based on grain size and geochemical properties of sediment records from the southernmost continental margin of South America. Combined with published sediment records from the Scotia Sea, we argue for a considerable total... |
| Tipo: Text |
Palavras-chave: Paleoceanography; Drake Passage; Antarctic Circumpolar Current; Glacial-interglacial changes; Sedimentology. |
| Ano: 2015 |
URL: https://archimer.ifremer.fr/doc/00351/46233/46119.pdf |
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| Cheshire, Heather; Thurow, Juergen. |
| Guaymas Basin, Gulf of California, is a restricted basin located under the present-day wet/dry subtropical divide (similar to 27 degrees N) and is ideally circumstanced for detecting variations in the North Pacific Subtropical High (NPSH)/Trade Wind system. Controlled by climate cell boundary displacement, NPSH midwinter location was the primary influence on timing and intensity of upwelling seasons in Guaymas Basin. Analysis of high-resolution X-ray fluoresence data and sediment fabric log from 75% laminated Core MD02-2517/2515, western Guaymas Basin, reveals systematic changes in NPSH behavior over the last similar to 55 kyr BP. Southward displacement of the wet/dry subtropical divide controlled upwelling-related diatom productivity, while sea level and... |
| Tipo: Text |
Palavras-chave: Quaternary; Paleoceanography; X-ray fluorescence; Laminated sediment. |
| Ano: 2013 |
URL: https://archimer.ifremer.fr/doc/00264/37527/35762.pdf |
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| Waelbroeck, C.; Kiefer, T.; Dokken, T.; Chen, M. -t.; Spero, H. J.; Jung, S.; Weinelt, M.; Kucera, M.; Paul, A.. |
| Estimates of the change in surface seawater delta O-18 (delta O-18(sw)) between the Last Glacial Maximum (LGM) and Late Holocene (LH) are derived from homogenous data sets with rigorous age control, namely MARGO sea surface temperature (SST) estimates and oxygen isotopic ratios (delta O-18) of planktonic foraminifers. Propagation of uncertainties associated with each proxy allows the identification of robust patterns of change in delta O-18(sw). Examination of these patterns on a regional scale highlights which changes in surface currents and hydrological cycle are consistent with both planktonic isotopic data and reconstructed SST. Positive local annual mean LGM-LH delta O-18(sw) anomalies characterize the glacial tropical Indian Ocean, portions of the... |
| Tipo: Text |
Palavras-chave: Paleoceanography; Surface water oxygen isotopic ratio; Planktonic foraminifers; Last Glacial Maximum. |
| Ano: 2014 |
URL: https://archimer.ifremer.fr/doc/00297/40870/39909.pdf |
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| Mudie, Peta J.; Marret, Fabienne; Mertens, Kenneth; Shumilovskikh, Lyudmila; Leroy, Suzanne A. G.. |
| We present the first comprehensive taxonomic and environmental study of dinoflagellate cysts in 185 surface sediment samples from the Black Sea Corridor (BSC) which is a series of marine basins extending from the Aegean to the Aral Seas (including Marmara, Black, Azov and Caspian Seas). For decades, these low-salinity, semi-enclosed or endorheic basins have experienced large-scale changes because of intensive agriculture and industrialisation, with consequent eutrophication and increased algal blooms. The BSC atlas data provide a baseline for improved understanding of linkages between surface water conditions and dinoflagellate cyst (dinocyst) distribution, diversity and morphological variations. By cross-reference to dinocyst occurrences in sediment cores... |
| Tipo: Text |
Palavras-chave: Phytoplankton; Harmful algae; Biodiversity; Paleoceanography; Surface samples. |
| Ano: 2017 |
URL: http://archimer.ifremer.fr/doc/00387/49824/50408.pdf |
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| Rutledal, Sunniva; Berben, Sarah M.p.; Dokken, Trond M.; Van Der Bilt, Willem G.m.; Cederstrøm, Jan Magne; Jansen, Eystein. |
| Geochemically distinct volcanic ash (tephra) deposits are increasingly acknowledged as a key geochronological tool to synchronize independent paleoclimate archives. Recent advances in the detection of invisible (crypto) tephra have led to the ongoing establishment, development and integration of regional tephra lattices. These frameworks offer an overview of the spatial extent of geochemically characterized tephra from dated eruptions – a valuable tool for precise correlation of paleorecords within these areas. Here, we harness cryptotephra analysis to investigate the occurrence of two well-known tephra markers from the Last Glacial Period (i.e. FMAZ II-1 (26.7 ka b2k) and NAAZ II (II-RHY-1) (55.3 ka b2k)), in marine sediment cores from the Nordic,... |
| Tipo: Text |
Palavras-chave: Tephrochronology; Cryptotephra Tephrostratigraphy; Tephra isochrons; FMAZ II; NAAZ II; Geochemistry; Paleoceanography; Marine sediment cores Quaternary; North Atlantic Ocean. |
| Ano: 2020 |
URL: https://archimer.ifremer.fr/doc/00614/72659/71665.pdf |
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| Martinez-mendez, G.; Hebbeln, D.; Mohtadi, M.; Lamy, F.; De Pol-holz, R.; Reyes-macaya, D.; Freudenthal, Tim. |
| The Antarctic Intermediate Water (AAIW) is a key player in global-scale oceanic overturning processes and an important conduit for heat, fresh water, and carbon transport. The AAIW past variability is poorly understood mainly due to the lack of sedimentary archives at intermediate water depths. We present records of benthic stable isotopes from sediments retrieved with the seafloor drill rig MARUM-MeBo at 956m water depth off northern Chile (GeoB15016, 27 degrees 29.48S, 71 degrees 07.58W) that extend back to 970ka. The sediments at this site are presently deposited at the boundary between AAIW and Pacific Deep Water (PDW). For previous peak interglacials, our results reveal similar benthic C-13 values at site GeoB15016 and of a newly generated stack of... |
| Tipo: Text |
Palavras-chave: Paleoceanography; AAIW; Advection changes. |
| Ano: 2013 |
URL: https://archimer.ifremer.fr/doc/00263/37459/35821.pdf |
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| Yiou, P; Vimeux, F; Jouzel, J. |
| The four climatic cycles obtained from the Vostok ice core offer a unique opportunity to study the high-frequency paleoclimatic variability, i.e., on time scales smaller than 15 kyr. We focused our study on the deuterium (deltaD) and deuterium excess (d) records, which are proxies for local temperature and remote evaporation source temperature and hence give us access to spatial climatic variations. Spectral analyses of paleoclimatic records have shown that the last glacial period (110-15 kyr before present) is characterized by large and fast temperature oscillations. Examples of such variations in the Northern Hemisphere are the so-called Dansgaard-Oeschger oscillations and Heinrich events. At Vostok, these oscillations are also imprinted in the ice, with... |
| Tipo: Text |
Palavras-chave: Climate dynamics; Antarctica; Meteorology and Atmospheric Dynamics; Paleoclimatology; Paleoceanography. |
| Ano: 2001 |
URL: https://archimer.ifremer.fr/doc/00221/33219/31699.pdf |
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| Registros recuperados: 49 | |
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