Consulta: subjectFacets:"Carbonate"
Registros recuperados: 9
Data/hora: 02/06/2024 11:36:12

Seasonal variations of downward particle fluxes in front of a reef pass (Moorea Island, French Polynesia)
Provedor de dados: 5
Autores: Schrimm, M; Heussner, S; Buscail, R.
Downward particle fluxes off the Taotoi Pass, a typical Polynesian lagoon pass, have been measured over an annual cycle by means of an array of three mooring lines deployed at 40 m depth on the external sandy plain seawards of the Tiahura reef. Each line was equipped with two hand-operated sediment traps located 1.5 and 10 m above the bottom. During the 1-year survey, the traps were deployed for seven periods of 2-3 weeks. One line equipped with an automated trap was further deployed at 400 m depth on the deep fore-reef slope to collect deep settling particles over two consecutive 6-month periods. For all periods investigated, fluxes on the external plain were highest in front of the pass, and decreased by half on either side (up- and downstream with...
Tipo: Text
Palavras-chave: Flux particulaire; Exportation de carbone; Récif corallien; Carbone organique; Carbonate; Particle flux; Carbon export; Coral reefs; Organic carbon; Carbonate.
Ano: 2002
URL: http://archimer.ifremer.fr/doc/00322/43320/42934.pdf

Reconstruction of productivity signal and deep-water conditions in Moroccan Atlantic margin (similar to 35 degrees N) from the last glacial to the Holocene
Provedor de dados: 5
Autores: El Frihmat, Yassine; Hebbeln, Dierk; Jaaidi, E. L. Bachir; Mhammdi, Nadia.
In order to assess the changes in sea-surface hydrology and productivity signal from the last glacial to the Holocene; a set of isotopic, geochemical and microgranulometric proxies was used for this study. Former studies revealed that the reconstruction of paleoproductivity from ocean sediment gives different results depending the measurement used. The comparison between our productivity proxies (total organic carbon, carbonate and planktonic delta C-13) as well as previous results in nearby location indicates that the planktonic delta C-13 responds better to marine productivity changes and represents therefore a suitable proxy for paleoproductivity reconstruction in our studied area. The productivity signal reveals two main enrichments during the Young...
Tipo: Text
Palavras-chave: Paleoproductivity; Larache margin; Late quaternary; Total organic carbon; Carbonate; Planktonic delta C-13.
Ano: 2015
URL: https://archimer.ifremer.fr/doc/00352/46274/46045.pdf

Hydrothermal carbonate chimneys from a continental rift (Afar Rift): Mineralogy, geochemistry, and mode of formation
Provedor de dados: 5
Autores: Dekov, V.m.; Egueh, N. M.; Kamenov, G. D.; Bayon, G.; Lalonde, S.v.; Schmidt, M.; Liebetrau, V.; Munnik, F.; Fouquet, Yves; Tanimizu, M.; Awaleh, M. O.; Guirreh, I.; Le Gall, B.
Carbonate chimney-like deposits up to 60 m high are scattered or arranged in rows at the shores of a desiccating hypersaline and alkaline lake from a continental rift setting (Lake Abhé, Afar Rift, Djibouti). The chimneys formed sub-aqueously in the lake water body at a higher water level than observed today. Alternating calcite and low-Mg calcite + silica concentric layers compose the chimney structures. Mineralogical and geochemical investigations of the chimneys, lake water, and hot spring (hydrothermal) fluids suggest that the chimneys are a result of rapid carbonate precipitation during the mixing of hydrothermal fluids with lake water. In contrast to the hot spring fluid, lake water is enriched in HREE and possesses a pronounced positive Ce anomaly,...
Tipo: Text
Palavras-chave: Carbonate; Chimney; Continental rift; H-C-O-Ca-Sr-Nd-Pb-Th-U-isotopes; Hydrothermalism.
Ano: 2014
URL: http://archimer.ifremer.fr/doc/00206/31762/30172.pdf

Atlantic Meridional Overturning Circulation during the Last Glacial and Deglacial: Inferences from the Atlantic Tropical Thermocline Temperature and Seawater Radiocarbon Activity
Provedor de dados: 5
Autores: Huang, Enqing.
This thesis aims to investigate variations of the last glacial and deglacial Atlantic Ocean circulation, with emphasize on the Atlantic deepwater ventilation rate during the Last Glacial Maximum (LGM). The highlights of the thesis are as the followings: (1) the modern frontal zone between the North Atlantic and the South Atlantic central waters off NW Africa shifted to the south during the last glacial and deglacial time periods. (2) The radiocarbon-based circulation age of the deep Atlantic (&gt; 1500 m) was estimated to be less than 400 years during the LGM, which was equal to or less than its pre-bomb value. Therefore, the LGM deep Atlantic was inferred to be well ventilated. (3) The abyssal Atlantic (below 2500 m) prior to the LGM was more depleted in...
Tipo: Text
Palavras-chave: Climate change; Ocean circulation; Atlantic Ocean; Glacial; Deglacial; Thermocline; Radiocarbon; Global carbon cycle; Foraminifera; Carbonate; Trace elements; Deep ocean ventilation rates.
Ano: 2013
URL: https://archimer.ifremer.fr/doc/00493/60446/63891.pdf

Reef Carbonate Productivity During Quaternary Sea Level Oscillations
Provedor de dados: 5
Autores: Husson, L.; Pastier, A. -m.; Pedoja, K.; Elliot, M.; Paillard, D.; Authemayou, C.; Sarr, A. -c.; Schmitt, A.; Cahyarini, S. Y.
Global variations in reef productivity during the Quaternary depend on external parameters that may alter the global chemical balance in the oceans and atmosphere. We designed a numerical model that simulates reef growth, erosion, and sedimentation on coastlines undergoing sea level oscillations, and uplift or subsidence. We further develop a probabilistic evaluation that accounts for variable vertical ground motion, erosion, and foundation morphologies. Absolute sea level change appears primordial, as productivity must have increased by an order of magnitude since the onset of the glacial cycles, approximate to 2.6 Ma. But most important is relative sea level change, i.e., eustasy modulated by uplift or subsidence, that rejuvenates the accommodation space...
Tipo: Text
Palavras-chave: Coral reefs; Sea level; Carbonate; Modeling; Paleoclimate.
Ano: 2018
URL: https://archimer.ifremer.fr/doc/00638/74993/75789.pdf

Sea surface temperature, productivity, and terrestrial flux variations of the southeastern South China Sea over the past 800000 years (IMAGES MD972142)
Provedor de dados: 5
Autores: Shiau, Liang-jian; Yu, Pai-sen; Wei, Kuo-yen; Yamamoto, Masanobu; Lee, Teh-quei; Yu, Ein-fen; Fang, Tien-hsi; Chen, Min-te.
Variations in sea surface temperature (SST), productivity, and biogenic components such as total organic carbon (TOC), carbonate, and opal contents measured from IMAGES (International Marine Global Changes Study) core MD972142 provide information about long-term paleoceanographic changes during the past similar to 870000 years in the southeastern South China Sea (SCS). MD972142 U-37(k)-SSTs varied from 25 to 29 degrees C, paralleling the glacial to interglacial changes. MD972142 biogenic components show relatively high carbonate and opal, and low TOC contents in interglacial stages, and low carbonate and opal and high TOC contents in glacial stages, and these variations appear to be sensitive to regional terrestrial sediment input and productivity. Our...
Tipo: Text
Palavras-chave: Total organic carbon; Carbonate; Opal; Productivity; Sea surface temperature; South China Sea; Monsoon; IMAGES.
Ano: 2008
URL: https://archimer.ifremer.fr/doc/00237/34817/33682.pdf

Sedimentation adjacent to atolls and volcano-cored carbonate platforms in the Mozambique Channel (SW Indian Ocean)
Provedor de dados: 5
Autores: Counts, John; Jorry, Stephan; Leroux, Estelle; Miramontes, Elda; Jouet, Gwenael.
Recently acquired data from the Iles Eparses (southwestern Indian Ocean) reveal new information about the geomorphology, depositional processes, and sedimentary deposits on the slopes of atolls and atoll-like platforms. The deposits discussed here lie on the deepwater flanks of isolated, inactive volcanos that are capped by shallow, relatively flat carbonate platforms 45–210 km2 in area. Much of the slope geomorphology is controlled by the underlying volcanic edifice. Steep (~25–35°) upper slopes consist of outcrops of volcanic basement, smooth banks, failure scarps, and channels. Sedimentary features seen in the lower slope and proximal basin (2000–3500 m deep) consist of channels, levees, lobes, and mass transport deposits (MTDs). In places, channels...
Tipo: Text
Palavras-chave: Atoll; Carbonate; Indian Ocean; Slope; Deepwater sediments.
Ano: 2018
URL: https://archimer.ifremer.fr/doc/00450/56136/57802.pdf

Shallow rocky bottom benthic assemblages as calcium carbonate producers in the Alboran Sea (southwestern Mediterranean)
Provedor de dados: 5
Autores: Cebrian, E; Ballesteros, E; Canals, M.
Zonation patterns and species composition of the different assemblages encountered along the bathymetric axis are considered in order to quantify the biomass and calcium carbonate content of communities thriving in rocky bottoms of La Herradura (southwestern Mediterranean) between 0 and 50 m depth. Algal biomass is lower but total biomass is slightly higher to values recorded in other Mediterranean areas due to the high biomass of suspension feeders. Since most of the animals and algae with high biomass have calcareous skeletons, the calcimass is rather high (1 100 to 2400 g . CaCO3.m(-2)) when compared to other temperate and Mediterranean sites. A tentative estimate of yearly carbonate production yields 1 000 g . CaCO3.m(-2).y(-1) for the rocky bottoms of...
Tipo: Text
Palavras-chave: Carbonate; Fonds rocheux; Communautés benthiques; Production; Mer Méditerranée; Calcium carbonate; Rocky bottoms; Benthic assemblages; Production; Mediterranean Sea.
Ano: 2000
URL: http://archimer.ifremer.fr/doc/00324/43565/44062.pdf

Geochemical and sedimentology of core sediments and the influence of human activities: Qusier, Safaga and Hurghada Harbors, Red Sea Coast, Egypt
Provedor de dados: 20
Autores: Mohamed, A.W.
The grain size distribution and arameters, major and trace elements, carbonate, total phosphorus, organic carbon and total organic matter has been assessed for core sediments collected in the intertidal area of Qusier, Safaga and Hurghada harbors in July 2002. Mud is the dominant fraction in almost all samples of Qusier core and some samples of Safaga and Hurghada cores. The reason for the high mud content of all Qusier core samples and some samples of Safaga and Hurghada cores is due to the terrigenous flux of wadies, phosphate deposits, landfill and dredging in these areas. Metals concentrations in the core sediments vary between sites within a wide range for Cu, Zn, Pb, V, Ni and Cd. Concentration of metals in the sediments at the top of cores is the...
Tipo: Journal Contribution
Palavras-chave: Trace elements; Carbonate; Anthropogenic impacts; Remediation Environments Grain size Marine environment Marine pollution Organic matter Marine environment Organic matter Environment http://aims.fao.org/aos/agrovoc/c_4610 http://aims.fao.org/aos/agrovoc/c_5387 http://aims.fao.org/aos/agrovoc/c_2593.
Ano: 2005
URL: http://hdl.handle.net/1834/1248