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| Registros recuperados: 49 | |
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| Meland, My; Jansen, E; Elderfield, H; Dokken, Tm; Olsen, A; Bellerby, Rgj. |
| In core top samples in the Nordic Seas, Mg/Ca ratios of N. pachyderma ( sin.) are generally consistent with previous high-latitude calibration data but do not reflect the modern calcification temperature gradient from 2 degrees C in the northwest to 8 degrees C in the southeast. This is because Mg/Ca ratios in foraminiferal shells from the central Nordic Seas are similar to 0.4 mmol/mol higher than expected from calibrations of Nurnberg ( 1995) and Elderfield and Ganssen ( 2000). The enhanced Mg/Ca ratios are observed in an area with low sedimentation rates (< similar to 5 cm/kyr). Possible factors that may cause this include bioturbation, Holocene variability in old core tops, dissolution, pore water chemistry, occurrence of volcanic ash, and other... |
| Tipo: Text |
Palavras-chave: Planktonic foraminifera; N. pachyderma (sin.); Mg/Ca; Paleothermometry; Paleoceanography; Nordic Seas. |
| Ano: 2006 |
URL: https://archimer.ifremer.fr/doc/00234/34559/33319.pdf |
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| Respschläger, Janne. |
| The Atlantic meridional overturning circulation (AMOC) transports warm saline water from low to high northern latitudes where it cools, sinks down and returns southward as deepwater flow. By the heat transfer from low to high latitudes, AMOC contributes in balancing the global energy budget and thus is an important part of global climate system. Within this study the impact of AMOC changes on surface and deepwater hydrography of the subtropical North Atlantic is investigated by the use of high-resolution sediment cores from a coring site located south of the Azores at the eastern flank of the Mid Atlantic Ridge. The Azores coring site is situated in the subtropical eastern North Atlantic (NA) at the boundary between warm Subtropical Gyre Water (STG) and... |
| Tipo: Text |
Palavras-chave: Paleoceanography; AMOC; Subtropical gyre; Deglacial; Multiproxy SST; BWT; Stable isotopes; Planktonic and benthic foraminifera. |
| Ano: 2013 |
URL: https://archimer.ifremer.fr/doc/00493/60444/63889.pdf |
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| Mortyn, Pg; Charles, Cd; Ninnemann, Us; Ludwig, K; Hodell, Da. |
| Many applications of the Vostok ice core depend critically on the ability to make stratigraphic ties to marine records in the adjacent Southern Ocean. Here we present oxygen isotopic records from high accumulation rate sites in the South Atlantic sector of the Southern Ocean, collected for the purpose of complementing the recently extended deltaD record from the Vostok ice core. The combination of several planktonic foraminiferal delta(18)O records from northern subantarctic piston cores demonstrates that all of the millennial-scale oscillations expressed in the Vostok ice core over the last 60 ky are also present in marine records. The observations also support the assumption that the millennial-scale oscillations common to both marine and ice archives... |
| Tipo: Text |
Palavras-chave: Paleoclimatology; Paleoceanography; Meteorology and atmospheric dynamics : paleoclimatology. |
| Ano: 2003 |
URL: https://archimer.ifremer.fr/doc/00226/33707/32126.pdf |
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| Seo, Inah; Lee, Yuri; Lee, Yong Il; Yoo, Chan Min; Hyeong, Kiseong. |
| This paper investigates paleoceanographic changes at a central equatorial Pacific site (6 degrees 40N, 177 degrees 28W) since the last glacial maximum using planktic foraminifera assemblages, together with the oxygen isotope (O-18) and Mg/Ca compositions of three species (Globigerinoides sacculifer, Pulleniatina obliquiloculata, and Globorotalia tumida) that dwell in the mixed layer, upper thermocline, and lower thermocline, respectively. While the Mg/Ca-derived temperatures of the mixed layer and lower thermocline varied within a narrow range from 18 ka onward, the upper thermocline temperature increased by as much as 3 degrees C during the last deglaciation (18-12 ka) with a simultaneous decrease of O-18. These changes are best explained by an enhanced... |
| Tipo: Text |
Palavras-chave: Planktic foraminifera; Geochemistry; Micropaleontology; Paleoceanography; Intertropical Convergence Zone; Last deglaciation. |
| Ano: 2016 |
URL: https://archimer.ifremer.fr/doc/00496/60721/65271.pdf |
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| Dera, Guillaume; Prunier, Jonathan; Smith, Paul L.; Haggart, James W.; Popov, Evgeny; Guzhov, Alexander; Rogov, Mikhail; Delsate, Dominique; Thies, Detlev; Cuny, Gilles; Puceat, Emmanuelle; Charbonnier, Guillaume; Bayon, Germain. |
| The breakup of Pangea and onset of growth of the Pacific plate led to several paleoenvironmental feedbacks, which radically affected paleoclimate and ocean chemistry during the Jurassic. Overall, this period was characterized by intense volcanic degassing from large igneous provinces and circum-Panthalassan arcs, new oceanic circulation patterns, and changes in heat and humidity transports affecting continental weathering. Few studies, however, have attempted to unravel the global interactions linking these processes over the long-term. In this paper, we address this question by documenting the global changes in continental drainage and surface oceanic circulation for the whole Jurassic period. For this purpose, we present 53 new neodymium isotope values... |
| Tipo: Text |
Palavras-chave: Neodymium isotopes; Jurassic; Paleoclimate; Paleoceanography; Continental drainage. |
| Ano: 2015 |
URL: http://archimer.ifremer.fr/doc/00179/29015/27443.pdf |
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| Hoffman, Jeremy Scott. |
| This dissertation explores one overarching question relevant to the paleoclimate of the latest Pleistocene glacial cycle (approximately the last 130,000 years): “How did spatial and temporal evolution of ocean temperature, both at the surface and interior, relate to other parts of the climate system in the late Pleistocene?” Results from three studies are presented that seek to address longstanding questions in paleoceanography and paleoclimatology for the late Pleistocene using a combination of novel and accepted statistical and geochemical analysis techniques and leveraging comparisons with available global climate model data. The last interglaciation (LIG; ~129-116 ka) was the most recent period in Earth’s history with higher-than-present global sea... |
| Tipo: Text |
Palavras-chave: Paleoclimate; Interglacial; Heinrich events; Deglacial; Paleoceanography; Climate. |
| Ano: 2016 |
URL: https://archimer.ifremer.fr/doc/00505/61702/65670.pdf |
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| Beaufort, Luc; Bolton, Clara T; Sarr, Anta-clarisse; Sucheras-marx, Baptiste; Rosenthal, Yair; Donnadieu, Yannick; Barbarin, Nicholas; Bova, Samantha; Cornuault, Pauline; Gally, Yves; Gray, Emmeline; Mazur, Jean-charles; Tetard, Martin. |
| The effect of global climate cycles driven by Earth’s orbital variations on evolution is poorly understood because of difficulties achieving sufficiently-resolved records of past evolution. The fossil remains of coccolithophores, a key calcifying phytoplankton group, enable an exceptional assessment of the impact of cyclic orbital-scale climate change on evolution because of their abundance in marine sediments, and because coccolithophores demonstrate extreme morphological plasticity in response to the changing environment1,2. Recently, evolutionary genetic analyses linked broad changes in Pleistocene fossil coccolith morphology to species radiation events3. Here, using high-resolution coccolith data, we show that during the last 2.8 million years... |
| Tipo: Text |
Palavras-chave: Paleoceanography; Climate cycles; Global carbon cycle; Phytoplankton evolution; Tropical seasonality. |
| Ano: 2020 |
URL: https://archimer.ifremer.fr/doc/00658/77054/78353.pdf |
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| Cortes Sanchez, Miguel; Jimenez Espejo, Francisco J.; Simon Vallejo, Maria D.; Gibaja Bao, Juan F.; Carvalho, Antonio Faustino; Martinez-ruiz, Francisca; Rodrigo Gamiz, Marta; Flores, Jose-abel; Paytan, Adina; Lopez Saez, Jose A.; Pena-chocarro, Leonor; Carrion, Jose S.; Morales Muniz, Arturo; Rosello Izquierdo, Eufrasia; Riquelme Cantal, Jose A.; Dean, Rebecca M.; Salgueiro, Emilia; Martinez Sanchez, Rafael M.; De La Rubia De Gracia, Juan J.; Lozano Francisco, Maria C.; Vera Pelaez, Jose L.; Llorente Rodriguez, Laura; Bicho, Nuno F.. |
| New data and a review of historiographic information from Neolithic sites of the Malaga and Algarve coasts (southern Iberian Peninsula) and from the Maghreb (North Africa) reveal the existence of a Neolithic settlement at least from 7.5 cal ka BP. The agricultural and pastoralist food producing economy of that population rapidly replaced the coastal economies of the Mesolithic populations. The timing of this population and economic turnover coincided with major changes in the continental and marine ecosystems, including upwelling intensity, sea-level changes and increased aridity in the Sahara and along the Iberian coast. These changes likely impacted the subsistence strategies of the Mesolithic populations along the Iberian seascapes and resulted in... |
| Tipo: Text |
Palavras-chave: Abrupt climate change; Mesolithic-Neolithic transition; South Iberia; Holocene; Migration; Hunter-fisher-gatherers; Paleoceanography. |
| Ano: 2012 |
URL: https://archimer.ifremer.fr/doc/00266/37678/35767.pdf |
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| Chang, Yp; Wu, Sm; Wei, Ky; Murayama, M; Kawahata, H; Chen, Mt. |
| Biogenic carbonate and organic carbon content of two deep sea cores (MD012404 and ODP site 1202) are measured to reconstruct surface ocean productivity variations in areas of the Okinawa Trough in the Western Pacific where the modern climate is highly sensitive to the East Asian monsoon and precipitation/river runoff. Based on foraminiferal isotope stratigraphy and AMS C-14 dating, the age models of the cores indicate that core MD012404 shows relatively low sedimentation rates with 50 cm ky(-1) on average, and that the sedimentation rates in core ODP 1202 are extremely high with an average of 500 cm ky(-1). Total organic carbon (TOC) and carbonate contents in core ODP 1202 are 0.56% and 6.80% on average, respectively, and are 0.62% and 15.86%,... |
| Tipo: Text |
Palavras-chave: IMAGES; ODP; Total organic carbon; Calcium carbonate; Okinawa Trough; Paleoceanography; Climate change; East Asian monsoon. |
| Ano: 2005 |
URL: https://archimer.ifremer.fr/doc/00229/34064/32627.pdf |
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| Mazaud, A.; Kissel, C.; Laj, C.; Sicre, M. A.; Michel, E.; Turon, J. L.. |
| We examine the magnetic mineral deposition in three cores located at midlatitude sites in the South Indian Ocean, in an area where sediment eroded from the Kerguelen-Crozet plateau and transported by the marine currents, principally the Antarctic Circum Current, accumulates at a high sedimentation rate. We focus on Marine Isotopic Stage 3, characterized by large climatic fluctuations at northern latitudes, and compare the obtained records to the climatic records at Byrd ( Antarctica) and Summit (GISP2, Greenland) and to the North Atlantic Deep Water variations in the North Atlantic. Magnetic mineral deposition at the studied sites exhibits a profile with maxima at the time of Heinrich events H4 and H5, which suggests a strong Antarctic Circum Current when... |
| Tipo: Text |
Palavras-chave: Paleoceanography; South; Indian; Ocean; Paleoclimatology and paleoceanography; Environmental magnetism; Interhemispheric phasing. |
| Ano: 2007 |
URL: https://archimer.ifremer.fr/doc/00235/34612/32954.pdf |
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| Sicre, Ma; Bard, E; Ezat, U; Rostek, F. |
| The C(37)-C(39) alkenones were quantified in suspended particulate matter obtained from the surface waters of the North Atlantic, including the Nordic seas, over a temperature range of 4degrees20 C. U(37)(K') values were linearly correlated to temperature over the entire range covered by our data set, i.e., 420 C (U(37)(K') = 0.027T + 0.036, r(2) = 0.97). The compilation of water column data from the Atlantic, Pacific, and Southern Ocean and Mediterranean Sea suggests that the linear model may not be the best function for fitting U(37)(K') and in situ temperature values. It also shows that suspended matter data from warm waters (T >20degreesC) are still needed to constrain the equation of the global curve. High abundances of C(37: 4) were found in the... |
| Tipo: Text |
Palavras-chave: Alkenones; Paleotemperature; Calibration; Atlantic Ocean; Plankton; Geochemistry; Marine geochemistry; Global change; Biogeochemical processes (4805); Oceanography; Paleoceanography. |
| Ano: 2002 |
URL: https://archimer.ifremer.fr/doc/00223/33393/31866.pdf |
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| Koc, N; Labeyrie, L; Manthe, S; Flower, Bp; Hodell, Da; Aksu, A. |
| Well-preserved diatoms are present in high sedimentation rate Pleistocene cores retrieved on ocean Drilling Program (ODP) Legs 151, 152, 162 and IMAGES cruises of RN Marion Dufresne from the North Atlantic. Investigation of the stratigraphic occurrence of diatom species shows that the youngest diatom event observed in the area is the last occurrence (LO) of Proboscia curvirostris (Jouse) Jordan and Priddle. P. curvirostris is a robust species that can easily be identified in the sediments, and therefore can be a practical biostratigraphic tool. We have mapped its: areal distribution, and found that it stretches from 40 degreesN to 80 degreesN in the North Atlantic. Further, we have correlated the LO P. curvirostris to the oxygen isotope records of six... |
| Tipo: Text |
Palavras-chave: Biostratigraphy; North Atlantic; Diatoms; Pleistocene; Paleoceanography; Isotope stratigraphy; Oxygen. |
| Ano: 2001 |
URL: https://archimer.ifremer.fr/doc/00221/33210/31708.pdf |
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| Rustic, Gerald Thomas. |
| The El Niño Southern Oscillation (ENSO) has been implicated in large-scale climate shifts of the past millennia, but paleoclimate records from the dynamically vital eastern equatorial Pacific Ocean (EEP) spanning the past millennium are sparse. This has limited our understanding of tropical Pacific dynamics, leaving questions regarding the source of ENSO variability unanswered. Here I seek to address some of these questions regarding relationship between ENSO and tropical Pacific mean state, and the relationship between the tropical Pacific and large-scale climate. Mean EEP sea surface temperature (SST) for the past millennium was reconstructed using Mg/Ca ratios in Globigerinoides ruber from a sub-centennially resolved sediment core collected near the... |
| Tipo: Text |
Palavras-chave: Eastern tropical pacific; ENSO; Foraminifera; Paleoceanography; Paleoclimate. |
| Ano: 2015 |
URL: https://archimer.ifremer.fr/doc/00495/60657/64154.pdf |
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| Gallagher, Stephen J; Sagawa, Takuya; Henderson, Andrew C. G.; Saavedra-pellitero, Mariem; De Vleeschouwe, David; Black, Heather; Itaki, Takuya; Toucanne, Samuel; Bassetti, Maria-angela; Clemens, Steve; Anderson, William; Alvarez-zarikian, Carlos; Tada, Ryuji. |
| The Japan Sea is directly influenced by the Asian monsoon, a system that transports moisture and heat across southeast Asia during the boreal summer, and is a major driver of the Earth's ocean‐atmospheric circulation. Foraminiferal and facies analyses of a 460 kyr record from IODP Expedition 346 Site U1427 in the Japan Sea reveal a record of nutrient flux and oxygenation that varied due to sea level and East Asian monsoon intensity. The East Asian summer monsoon (EASM) was most intense during MIS (Marine Isotope Stage) 5e, 7e, 9e and 11c when the Tsushima Warm Current flowed into an unrestricted well mixed normal salinity Japan Sea. Whereas East Asian winter monsoon (EAWM) conditions dominated MIS 2, 4, 6 and 8 when sea level minima restricted the Japan... |
| Tipo: Text |
Palavras-chave: Tsushima Warm Current; Pleistocene; Holocene; Paleoceanography; East Asian summer monsoon; East Asian winter monsoon. |
| Ano: 2018 |
URL: http://archimer.ifremer.fr/doc/00444/55591/57215.pdf |
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| Oppo, Dw; Linsley, Bk; Rosenthal, Y; Dannenmann, S; Beaufort, L. |
| A detailed record of planktic delta(18)O from a sediment core in the Sulu Sea, located between the South China Sea and the western Pacific warm pool, reveals that for the past 400 kyr (1 kyr = 1000 years), delta(18)O variability on orbital timescales is similar to that caused by changes in ice volume alone. This result indicates that in the Sulu Sea, temperature-driven changes in planktic delta(18)O on orbital times scales were generally compensated for by the effects of sea level and changes in seasonal monsoon intensity on the local freshwater budget, as well as by other changes in the tropical hydrologic cycle and their attendant effects on surface water delta(18)O. Increased freshening of the western tropical Pacific warm pool is reminiscent of La Nina... |
| Tipo: Text |
Palavras-chave: Sulu Sea; Tropical hydrography; East Asian monsoon; IMAGES; Suborbital climate variability; Sea level; Paleoceanography; Marginal and semienclosed seas; Climate dynamics. |
| Ano: 2003 |
URL: https://archimer.ifremer.fr/doc/00226/33680/32047.pdf |
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| Gueguen, Bleuenn; Rouxel, Olivier; Rouget, Marie-laure; Bollinger, Claire; Ponzevera, Emmanuel; Germain, Yoan; Fouquet, Yves. |
| Ferromanganese (Fe-Mn) crusts are potential archive of the Ni isotope composition of seawater through time. In this study we aim at (1) understanding Ni isotope fractionation mechanisms and metal enrichment processes in Fe-Mn deposits, (2) addressing global vs. local control of Ni isotope composition of these deposits. Two Fe-Mn crusts from the North Pacific Ocean (Apuupuu Seamount, Hawaii) and two Fe-Mn crusts from the South Pacific Ocean (near Rurutu Island, Austral archipelago of French Polynesia) were characterized for their elemental geochemistry and Ni isotope composition. Geochemical analyses were performed at millimeter intervals in order to provide time-resolved record of Ni isotopes. Chronology and growth rates were determined using cosmogenic... |
| Tipo: Text |
Palavras-chave: Ferromanganese crusts; Nickel isotopes; Paleoceanography; Pacific Ocean; Biogeochemical cycling. |
| Ano: 2016 |
URL: http://archimer.ifremer.fr/doc/00341/45255/44696.pdf |
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| Dannenmann, S; Linsley, Bk; Oppo, Dw; Rosenthal, Y; Beaufort, L. |
| We have generated a new high-resolution record of variations in planktonic foraminiferal oxygen isotopes (delta(18)O) and Mg/Ca from a sediment core (IMAGES 97-2141) in the Sulu Sea located in the Philippine archipelago of western tropical Pacific. This record reveals distinct, suborbital-scale delta(18)O changes, most notably during Marine Isotope Stage 3 (MIS3) (similar to30,000 to 60,000 years B.P.). The amplitudes of these delta(18)O fluctuations (0.4 to 0.7parts per thousand) exceed that which can be attributed to sea level changes and must be due to changes in sea surface conditions. In the same interval, variations in planktonic foraminifera Mg/Ca suggest that suborbital surface ocean temperature variations of 1 to 1.5degreesC in the Sulu Sea were... |
| Tipo: Text |
Palavras-chave: Paleoceanography; Isotope stage 3; SE Asian Monsoon; Mg/Ca; Oxygen isotopes; Millennial-scale climate change; Paleoceanography; Climate dynamics. |
| Ano: 2003 |
URL: https://archimer.ifremer.fr/doc/00226/33681/32046.pdf |
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| Hines, Sophia Katharine Vizza. |
| Glacial-interglacial cycles, occurring at a period of approximately 100,000 years, have dominated Earth's climate over the past 800,000 years. These cycles involve major changes in land ice, global sea level, ocean circulation, and the carbon cycle. While it is generally agreed that the ultimate driver of global climate is changes in insolation, glacial cycles do not look like insolation forcing. Notably, there is a highly non-linear warming response at 100,000 years to a relatively small forcing, implicating a more complicated system of biogeochemical and physical drivers. The ocean plays a pivotal role in glacial-interglacial climate through direct equator-to-pole transport of heat and its role in the carbon cycle. The deep ocean contains 60 times more... |
| Tipo: Text |
Palavras-chave: Paleoceanography; Oceanography; Climate change; Glacial cycles; Ocean circulation; Ocean dynamics. |
| Ano: 2018 |
URL: https://archimer.ifremer.fr/doc/00493/60447/63892.pdf |
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| Crosta, X; Shemesh, A. |
| [1] Oceanic nutrient cycling in the Southern Ocean is supposed to have an important impact on glacial-interglacial atmospheric CO(2) changes and global climate. In order to characterize such nutrient cycling over the last two climatic cycles we investigated carbon and nitrogen isotopic ratios of diatom-bound organic matter (delta(13)C(diat) and delta(15)N(diat)- respectively) in two cores retrieved form the Atlantic and Indian sectors of the Antarctic Ocean. The two cores show the same isotopic patterns. The delta(13)C(diat) values are depleted during glacial periods and enriched during interglacial periods, indicating lower productivity during cold times. The delta(15)N(diat) values are enriched during glacial periods and depleted during interglacial... |
| Tipo: Text |
Palavras-chave: Southern Ocean; Paleoceanography; Geochemistry; Diatoms. |
| Ano: 2002 |
URL: https://archimer.ifremer.fr/doc/00223/33402/31859.pdf |
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| Registros recuperados: 49 | |
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