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Datasets with PANGAEA technical keyword @ORFOIS

Mostrando recursos 1 - 20 de 2.760

  1. Sedimentological analysis of sediments from Amundsen and Bellingshausen Seas, Southern Ocean

    Hillenbrand, Claus-Dieter

  2. Sedimentology of sites 14-141, 41-366, 47-397 and 79-544B

    Stein, Ruediger
    Along the N-S-transect of DSDP-Sites 5446, 397, 141, and 366, oxygen and carbon isotopes, flux rates of calcium carbonate, terrigenous matter, and biogenic opal, clay minerals and the size distribution of terrigenous partictes were determined in order to assess the ties between atmospheric and oceanic surface and deep-water circulation off northwest Africa during the late Neogene. During the last 9 m.y., both the paleoceanography in the eastern Atlantic and west African paleodimates were intimately correlated with the evolution of the polar ice sheets as reflected in the benthos d18O curves of the 4 DSDP-Sites. These records make it possible to distinguish...

  3. Sedimentology on cores off the South Orkney Plateau

    Grünig, Sigrun
    Grab samples and cores for sedimentological studies were retrieved along a N-S transect of the South Orkney Plateau margin. On the basis of morphology, the margin has been subdivided into shelf, upper continental slope, and a lower slope region cut by basins and ridges. Grain size, Sand component, and clay mineralogy were determined as well as water, organic carbon and carbonate contents. In addition, vane shear strength, magnetic intensity and the proportion of ice-rafted debris were measured, dating was done by detailed magnetic stratigraphy, the biofluctuation of the radiolarian Cycladophora davisiana and 230-Thorium analyses. Sediment facies distribution is controlled by numerous factors...

  4. Compilation of the results of EU-project BOFS

    BODC; Lowry, Roy K; Machin, P; Cramer, Ray N

  5. Compilation of scientific results of the EU project BENGAL

    Pfannkuche, Olaf; Rabouille, Christophe; Bassinot, Franck C; Galeron, Joelle; Rice, Anthony L; Bett, Brian J; Vangriesheim, Annick; Hall, Per; Brey, Thomas; Christiansen, Bernd; Springer, Barbara; Ragueneau, Olivier; Gooday, Andrew J; Wolff, George A; Grandel, Sibylle; Vanreusel, Ann; Lampitt, Richard Stephen; Duineveld, Gerard C A; Reyss, Jean-Louis; Megalovasilis, Pavlos; Dell'Anno, Antonio; Varnavas, Soterios; Grehan, Anthony J; Patching, John W; Roberts, Dai; Lamont, Peter; Danovaro, Roberto; Kiriakoulakis, Kostas; Turnewitsch, Robert; Witbaard, Rob; Cosson-Sarradin, Nathalie; Priede, Imants G; Popova, E E

  6. Compilation of sedimentation rates and smear slide analysis of DSDP sites

    Thiede, Jörn; Ehrmann, Werner
    A history of Mesozoie and Cenozoic palaeoenvironments of the North Atlantie Oeean has been developed based on a detailed analysis of the temporal and spatial distribution of major pelagie sediment facies, of hiatuses. of bulk sediment accumulation rates, and of concentrations and fluxes of the main deep-sea sediment components. The depositional history of the North Atlantic can be subdivided into three major phase: (a) Late Jurassie and Early Cretaceous phase: clastic terrigenous and biogenic pelagic sediment components accumulated rapidly under highly productive surface water masses over the entire occan basin; (b) Late Cretaceous to Early Miocene phase: relatively little terrigenous...

  7. Alkenone analyses of sediment cores from the western Arabian Sea

    Budziak, Dörte
    Records of total organic carbon (TOC) and C37 alkenones were used as indicators for past primary productivity in the western and eastern Arabian Sea. Data from GeoB 3005, an open ocean site in the western Arabian Sea upwelling area, are compared with similar records of GeoB 3007 from the Owen Ridge, Ocean Drilling Program (ODP) Site 723 from the continental margin off Oman and MD 900963 from the eastern Arabian Sea. TOC/C37 alkenone records together with other proxies used to reconstruct upwelling intensity, indicate periods of high productivity in tune with precessional forcing all over the Arabian Sea. Based on...

  8. Stable isotopes of foraminifers, mineralogy and ages of sediment core GeoB1523-1

    Rühlemann, Carsten; Diekmann, Bernhard; Mulitza, Stefan; Frank, Martin
    Today the western tropical Atlantic is the most important passage for cross-equatorial transfer of heat in the form of warm surface water flowing from the South into the North Atlantic. Circulation changes north of South America may thus have influenced the global thermohaline circulation system and high northern latitude climate. Here we reconstruct late Quaternary variations of western equatorial Atlantic surface circulation and Amazon lowland climate obtained from a multiproxy sediment record from Ceará Rise. Variations in the illite/smectite ratio suggest drier climatic conditions in the Amazon Basin during glacials relative to interglacials. The 230Thex-normalized fluxes and the 13C/12C record...

  9. Vertical flux and lithologic material in the Ross Sea

    Collier, Robert W; Dymond, Jack R; Honjo, Susumu; Manganini, Steven J; Francois, Roger; Dunbar, Robert G
    As part of the USJGOFS-AESOPS program, we deployed an array of moored sediment traps and determined the composition and vertical flux of particulate matter through the water column of the continental shelf environment of the Ross Sea. We deployed two moorings, with two traps each. One mooring was located in the southcentral Ross Sea along the line of AESOPS process studies; the other mooring was located in the northcentral Ross Sea. The flux in the southern Ross Sea was generally double that in the north, and there was a significant increase in flux into the deep traps indicating horizontal transport...

  10. Geochemistry, fluxes and nitrogen isotopic composition data of traps LP1 and EBC2-1 and cores GeoB4242-4 and Geo4301-1

    Freudenthal, Tim; Neuer, Susanne; Meggers, Helge; Davenport, Robert; Wefer, Gerold
    We compare total and biogenic particle fluxes and stable nitrogen isotope ratios (d15N) at three mooring sites along a productivity gradient in the Canary Islands region with surface sediment accumulation rates and sedimentary d15N. Higher particle fluxes and sediment accumulation rates, and lower d15N were observed in the upwelling influenced eastern boundary region (EBC) compared to the oligotrophic sites north of Gran Canaria [European Station for Time-Series in the Ocean, Canary Islands (ESTOC]] and north of La Palma (LP). The impact of organic matter degradation and lateral particle advection on sediment accumulation was quantified with respect to the multi-year flux...

  11. Geochemistry and soil characteristics of sediment core GeoB4234

    Freudenthal, Tim; Wagner, Thomas; Wenzhöfer, Frank; Zabel, Matthias; Wefer, Gerold
    Stable isotopes of sedimentary nitrogen and organic carbon are widely used as proxy variables for biogeochemical parameters and processes in the water column. In order to investigate alterations of the primary isotopic signal by sedimentary diagenetic processes, we determined concentrations and isotopic compositions of inorganic nitrogen (IN), organic nitrogen (ON), total nitrogen (TN), and total organic carbon (TOC) on one short core recovered from sediments of the eastern subtropical Atlantic, between the Canary Islands and the Moroccan coast. Changes with depth in concentration and isotopic composition of the different fractions were related to early diagenetic conditions indicated by pore water...

  12. Pore-water chemistry of abyssal Arabian Sea surface sediments

    Grandel, Sibylle; Rickert, Dirk; Schlüter, Michael; Wallmann, Klaus
    Benthic fluxes and pore-water compositions of silicic acid, nitrate and phosphate were investigated for surface sediments of the abyssal Arabian Sea during four cruises (1995-1998). Five sites located in the northern (NAST), western (WAST), central (CAST), eastern (EAST), and southern (SAST) Arabian Sea were revisited during intermonsoonal periods after the NE- and SW-Monsoon. At these sites, benthic fluxes of remineralized nutrients from the sediment to the bottom water of 36-106, 102-350 and 4-16 mmol/m**2/yr were measured for nitrate, silicic acid and phosphate, respectively. The benthic fluxes and pore-water compositions showed a distinct regional pattern. Highest fluxes were observed in the...

  13. X-ray fluorescence measurements and bulk organic carbon analyses of ODP Hole 175-1075A

    Jahn, Britta; Schneider, Ralph R; Müller, Peter J; Donner, Barbara; Röhl, Ursula
    Records of organic matter accumulation, organic carbon isotopic composition and iron content covering the last 1.7 Ma are presented for the Congo Fan Ocean Drilling Program (ODP) Site 1075, and are compared with their counterparts from ODP Site 663 in the equatorial upwelling region. They are discussed with regard to variations in African precipitation and Congo River discharge and in the context of changes in trade-wind-driven marine productivity for the tropical Atlantic at periodicities typical of Milankovitch forcing. On the Congo Fan, elevated total organic carbon mass accumulation rates (TOC MAR) and Fe intensities occur predominantly during interglacial periods when...

  14. Sedimentologic and magnetic data of sediment cores on the western slope of the Mid-Atlantic Ridge

    Franke, Christine; Hofmann, Daniela; von Dobeneck, Tilo
    The relative paleointensity (RPI) method assumes that the intensity of post depositional remanent magnetization (PDRM) depends exclusively on the magnetic field strength and the concentration of the magnetic carriers. Sedimentary remanence is regarded as an equilibrium state between aligning geomagnetic and randomizing interparticle forces. Just how strong these mechanical and electrostatic forces are, depends on many petrophysical factors related to mineralogy, particle size and shape of the matrix constituents. We therefore test the hypothesis that variations in sediment lithology modulate RPI records. For 90 selected Late Quaternary sediment samples from the subtropical and subantarctic South Atlantic Ocean a combined paleomagnetic...

  15. Alkenone and foraminifera records from sediment samples off Namibia

    Mollenhauer, Gesine; Eglinton, Timothy I; Ohkouchi, Naohiko; Schneider, Ralph R; Müller, Peter J; Grootes, Pieter Meiert; Rullkötter, Jürgen
    Radiocarbon stratigraphy is an essential tool for high resolution paleoceanographic studies. Age models based on radiocarbon ages of foraminifera are commonly applied to a wide range of geochemical studies, including the investigation of temporal leads and lags. The critical assumption is that temporal coupling between foraminifera and other sediment constituents, including specific molecular organic compounds (biomarkers) of marine phytoplankton, e.g. alkenones, is maintained in the sediments. To test this critical assumption in the Benguela upwelling area, we have determined radiocarbon ages of total C37-C39 alkenones in 20 samples from two gravity cores and three multicorer cores. The cores were retrieved from...

  16. Bulk geochemistry and grain-size composition of surface sediments from the SW Atlantic

    Frenz, Michael; Höppner, René; Stuut, Jan-Berend W; Wagner, Thomas; Henrich, Rüdiger
    Surface sediments from the South American continental margin surrounding tbe Argentine Basin were studied with respect to bulk geochemistry (Caeo) and C ) and grain-size composition (sand/silt/clay relation and terrigenous silt grain-size distribution). The grain-size distributions of the terrigenous silt fraction were unmixed into three end members (EMs), using an end-member modelling algorithm. Three unimodal EMs appear to satisfactorily explain the variations in the data set of the grain-size distributions ofterrigenous silt. The EMs are related to sediment supply by rivers, downslope transport, winnowing, dispersal and re-deposition by currents. The bulk geochemical composition was used to trace the distribution of...

  17. Analysis of minerals from Arctic Ocean sediments

    Vogt, Christoph
    The Arctic Ocean System is a key player regarding the climatic changes of Earth. Its highly sensitive ice Cover, the exchange of surface and deep water masses with the global ocean and the coupling with the atmosphere interact directly with global climatic changes. The output of cold, polar water and sea ice influences the production of deep water in the North Atlantic and controls the global ocean circulation ("the conveyor belt"). The Arctic Ocean is surrounded by the large Northern Hemisphere ice sheets which not only affect the sedimentation in the Arctic Ocean but also are supposed to induce the...

  18. Planktic foraminifera analyses of surface sediments and satellite data in the Canary Islands region

    Meggers, Helge; Freudenthal, Tim; Nave, Silvia Osorio; Targarona, Jordi; Abrantes, Fatima F; Helmke, Peer
    The Canary Islands region occupies a key position with respect to biogeochemical cycles, with the zonal transition from oligotrophic to nutrient-rich waters and the contribution of Saharan dust to the particle flux. We present the distribution of geochemical proxies (TOC, carbonate, d15N, d13Corg, C/N-ratio) and micropaleontological parameters (diatoms, dinoflagellates, foraminifera, pteropods), in 80 surface-sediment samples in order to characterise the influence of coastally upwelled water on the domain of the subtropical gyre. Results of the surface-sediment analyses confirmed the high biomass gradient from the coast to the open ocean inferred from satellite data of surface chlorophyll or SST. The distribution of...

  19. Chemical composition of bottom sediments from the Kara Sea and estuaries of the Ob and Enisey Rivers

    Gurvich, Evgeny G; Isaeva, Alexandra B; Dyomina, L V; Levitan, Mikhail A; Muravyov, K G
    Data obtained during Cruse 49 of R/V Dmitry Mendeleev and of post-cruise studies.

  20. Carbon and alkenone analysis on sediment core MD97-2151

    Zhao, Meixun; Huang, Chi-Yue; Wang, Chia-Chun; Wei, Ganjian
    We report 150 kyr records of U37K' sea-surface temperature (SST) and carbonate content with 150-200-year sampling resolution from the southern South China Sea (SCS) in the northern margin of the Western Pacific Warm Pool (WPWP) using IMAGES Core MD972151. The glacial/interglacial SST change is about 5 °C for Termination II (23.5 to 28.5°C) and 4°C for Termination I (24 to 28°C). The simultaneous rise of sea level and U37K' SST during Termination I suggests that sea-level change has played an important role in the SCS SST variability by influencing the exchange of tropical ocean warm surface water with the SCS...

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