|
|
|
| Registros recuperados: 49 | |
|
|
| Rogerson, M.; Cacho, I.; Jimenez-espejo, F.; Reguera, M. I.; Sierro, F. J.; Martinez-ruiz, F.; Frigola, J.; Canals, M.. |
| The eastern Mediterranean sapropels are among the most intensively investigated phenomena in the paleoceanographic record, but relatively little has been written regarding the origin of the equivalent of the sapropels in the western Mediterranean, the organic-rich layers (ORLs). ORLs are recognized as sediment layers containing enhanced total organic carbon that extend throughout the deep basins of the western Mediterranean and are associated with enhanced total barium concentration and a reduced diversity (dysoxic but not anoxic) benthic foraminiferal assemblage. Consequently, it has been suggested that ORLs represent periods of enhanced productivity coupled with reduced deep ventilation, presumably related to increased continental runoff, in close... |
| Tipo: Text |
Palavras-chave: Sapropel; Mediterranean; Sea level; Paleoceanography; Circulation. |
| Ano: 2008 |
URL: https://archimer.ifremer.fr/doc/00237/34825/33303.pdf |
| |
|
|
| 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 |
| |
|
|
| 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 |
| |
|
|
| 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 |
| |
|
|
| 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 |
| |
|
| |
|
|
| 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 |
| |
|
|
| 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 |
| |
|
|
| 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 |
| |
|
|
| 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 |
| |
|
|
| 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 |
| |
|
| |
|
|
| 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 |
| |
|
|
| 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 |
| |
|
|
| 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 |
| |
|
|
| 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 |
| |
|
|
| 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 |
| |
|
|
| 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 |
| |
|
|
| Bergue,Cristianini T.; Govindan,Abiraman. |
| The Eocene-Pliocene deep sea ostracodes from the ODP site 744A (Kerguelen Plateau) are herein studied under the taxonomic and paleoecologic aspects. 28 species are identified, being the genera Krithe, Cytherella and Dutoitella the most diversified. A faunal threshold was recorded in the Early Oligocene, which is tentatively explained under the knowledge of the paleoceanographical studies carried out not only in the Kerguelen Plateau but also in adjacent areas. The faunal turnover and variations in both richness and abundance possibly reflect the inception of psychrosphere and the influence of hydrological changes in the preservation of carapaces. Moreover, the influence of those changes on carbonate preservation is discussed as the cause of faunal... |
| Tipo: Info:eu-repo/semantics/article |
Palavras-chave: Cenozoic; Ostracodes; Paleoceanography; Paleozoogeography. |
| Ano: 2010 |
URL: http://www.scielo.br/scielo.php?script=sci_arttext&pid=S0001-37652010000300021 |
| |
|
|
| 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 |
| |
| Registros recuperados: 49 | |
|
|
|
