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Datasets of project "Quaternary Environment of the Eurasian North"

Mostrando recursos 1 - 20 de 4.490

  1. 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...

  2. Physical properties of deep sea sediments

    Holler, Peter R
    Erstmals quantitativ bearbeitete Rutschungen aus dem Tiefseebereich des äquatorialen Ostatlantiks liegen auf Hängen von 0,4 Grad und 0,7 Grad - das ist sehr viel flacher als die für statische Rutschungsauslösung benötigte kritische Hangneigung (14 Grad bis 16 Grad ). Im Gegensatz zu Flachwassergebieten kann bei Wassertiefen von über 4000 m natürlich der Einfluß von Wellenwirkung und Tidenhub auf die Hangstabilität vernachlässigt werden. Die Sedimentationsraten sind in diesem Bereich zur Bildung eines Porenwasserüberdruckes vielfach zu niedrig. Nach den Hangstabilitätsanalysen bilden hier Erdbeben den wirksamsten Auslösemechanismus für die Rutschungen. Dies gilt auch für Rutschungen an den Kontinentalrändern von Nordwest- und Westafrika sowie...

  3. Stable oxygen isotope in opal and seawater

    Anders, Tania-Maria
    Sauerstoff-Isotopenuntersuchungen wurden an frischem Diatomeenopal aus der obersten Wassersäule, Diatomeen aus Kulturen, sowie an sedimentärem Diatomeenopal durchgeführt, um die Anwendbarkeit von d18O-Signalen aus marinen Diatomeen für paläozeanographische Fragestellungen zu untersuchen. Diatomeenopal ist, besonders aus Sedimentproben, schwierig anzureichern. Physikalische und chemische Verfahren müssen mehrfach angewendet werden, um Proben zu erhalten, die den für Sauerstoff-Isotopenmessungen erforderlichen Reinheitsgrad aufweisen. Die Ausgangskonzentration an Diatomeen im Probenmaterial wirkt sich hierbei erheblich auf den Erfolg der Reinigung aus. Verläßliche und reproduzierbare d18O-Werte können nur an sehr reinen Diatomeenproben bestimmt werden. Mittels mikroskopischer Untersuchungen (Durchlichtmikroskopie, Rasterelektronenrnikroskopie), Röntgendiffraktametrie und geochernischer Analysen am ICP-MS können z.T. Art und Menge von Verunreinigungen...

  4. Paleointensities of sediment core PG1111, Lama Lake, northern Central Siberia

    Nowaczyk, Norbert R; Harwart, Stefanie K; Melles, Martin
    High-resolution analyses of rock magnetic and sedimentological parameters were conducted on an 11 m long sediment core from Lama Lake, Northern Siberia, which encompasses the late Pleistocene and the Holocene epochs. The results reveal a strong link between the median grain size of the magnetic particles, identified as magnetite, and the oxidation state of the sediment. Reducing conditions associated with a relative high total organic carbon (TOC) content of the sediment characterize the upper 7 m of the core (~ Holocene), and these have led to a partial dissolution of detrital magnetite grains, and a homogenization of grain-size-related rock magnetic...

  5. Rock magnetic record from Lama Lake

    Nowaczyk, Norbert R; Harwart, Stefanie K; Melles, Martin
    An 11 m long sediment core ftorn Lama Lake, Northern Siberia, has been subjected to intense sedimentological, geochemical and rock magnetic analyses. According to a palynologic investigation the recovered sediments cover the whole Holocene and the late Pleistocene reaching back to about 17 ka. IRM acquisition experiments, hysteresis loop and back field as well as thermomagnetic measurements revealed magnetite in the pseudo-single domain range as the only remanence carrier. Sharp rock magnetic boundaries occur at 20 and 745 cm sub-bottom depth that are clearly linked to shifts in the median grain size of the magnetite. These boundaries are close to...

  6. 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...

  7. Geochemical investigations of sediment profiles in the Norwegian-Greenland Sea

    Voelker, Antje H L
    High-, i.e. 15-140-yr-resolution climate records from sediment cores 23071, 23074, and PS2644 from the Nordic Seas were used to recon:;truct changes in the surface and deep water circulation during marine isotope stages 1-5.1, i.e. the last 82 000 yr. From this the causal links between the paleoceanographic signals and the Dansgaard-Oeschger events 1-21 revealed in 0180-ice-core records from Greenland were determined. The stratigraphy of the cores is based on the planktic 0180 curves, the minima of which were directly correlated with the GISP2-0180 record, numerous AMS 14C ages, and some ash layers. The planktic d18O and dl3C curves of all three...

  8. Tab 6.3 Compilation of 14C ages from Greenland

    see references

  9. Tab 6.3 Compilation of 14C ages from Greenland

    see references

  10. Sedimentology on two cores from Scoresby Sund, Greenland

    Marienfeld, Peter
    Reconstruction of the postglacial palaeoenvironmental evolution was the main objective of marine geological investigations in the Scorcsby Sund fjord system. For this purpose, samples of marine sediments, taken on RV Polarstern cruises ARK-V/3b and ARK-VII/3b in 1988 and 1990, have been analysed. All investigated fjord sediments are paratills. However, remarkable changes in sediment fabric and composition occur with depth in cores. They are attributable to different modes of sediment deposition. Therefore, a subdivision of the postglacial palaeoenvironmental history into periods of considerably different sedimentary conditions is feasible. The change of sedimentary fades with time is interpreted by deposition under changing climatic...

  11. Marine ice-rafted debris records and age determinations along the northern Eurasian margin

    Knies, Jochen; Kleiber, Hans Peter; Matthiessen, Jens; Müller, Claudia; Nowaczyk, Norbert R
    Ice-rafted debris (IRD) (>2 mm), input in eight sediment cores along the Eurasian continental margin (Arctic Ocean), have been studied over the last two glacial/interglacial cycles. Together with the revised chronologies and new micropaleontological data of two cores from the northern Barents Sea (PS2138) and northeastern Kara Sea (PS2741) spanning Marine Isotope Stages (MIS) 6 to 1, the IRD data give new insights into the glacial history of northern Eurasian ice-sheets over the last 150 ka. The chronologies of the cores are based on stable isotope records, AMS 14C datings, paleomagnetic and biostratigraphic data. Extensive episodes of northern Barents Sea ice-sheet...

  12. (Table 3) Different core locations in the North Atlantic, Nordic Seas, and the northern Barents Sea and their AMS 14C dated IRD events corresponding to andror are similar in timing with the Heinrich Events 1-4 in the North Atlantic

    Knies, Jochen; Kleiber, Hans Peter; Matthiessen, Jens; Müller, Claudia; Nowaczyk, Norbert R

  13. Physical and chemical oceanography in the Arctic Ocean

    Bauch, Dorothea
    Data from sections across the Eurasian Basin of the Arctic Ocean occupied by the German Research Vessel Polarstern in 1987 and by the Swedish icebreaker Oden in 1991 are used to derive information on the freshwater balance of the Arctic Ocean halocline and on the sources of the deep waters of the Nansen, Amundsen and Makarov basins. Salinity, d18O and mass balances allow separation of the river-runoff and the sea-ice meltwater fractions contained in the Arctic halocline. This provides the basis for tracking the river-runoff signal from the shelf seas across the central Arctic Ocean to Fram Strait. The halocline has...

  14. Sediment composition of the Central Arctic Ocean

    Spielhagen, Robert F; Baumann, Karl-Heinz; Erlenkeuser, Helmut; Nowaczyk, Norbert R; Nørgaard-Pedersen, Niels; Vogt, Christoph; Weiel, Dominik
    The sediment composition of deep-sea cores from the central Arctic Ocean, the Fram Strait, and the Yermak Plateau was analyzed for several parameters to reconstruct the history of marine paleoenvironment and terrestrial glaciation in the last 200,000 years. Layers with high amounts of coarse, terrigenous ice-rafted debris (IRD) and often high contents of smectite were deposited during extensive glaciations in northern Eurasia, when ice sheets reached the northern continental margins of the Barents and Kara seas and discharged icebergs into the Arctic Ocean. Intercalated layers with relatively low IRD and smectite contents, but abundant planktic foraminifers in the coarse fraction...

  15. Activity and biomass of small benthic biota in the central Arctic Ocean

    Soltwedel, Thomas; Schewe, Ingo
    Sediment samples collected during the expedition "Arctic Ocean '96" with the Swedish ice-breaker ODEN were investigated to estimate for the first time heterotrophic activity and total microbial biomass (size range from bacteria to small metazoans) from the perennially ice-covered central Arctic Ocean. Benthic activities and biomass were evaluated analysing a series of biogenic sediment compounds (i.e. bacterial exoenzymes, total adenylates, DNA, phospholipids, particulate proteins). In contrast to the very time-consuming sorting, enumeration and weight determination, analyses of biochemical sediment parameters may represent a useful method for obtaining rapid information on the ecological situation in a given benthic system. Bacterial cell...

  16. (Table 2) Biogenic sediment compounds and bacterial abundances of surface sediments in the central Arctic Ocean

    Soltwedel, Thomas; Schewe, Ingo

  17. (Table 2) Biogenic sediment compounds and bacterial abundances of surface sediments in the central Arctic Ocean

    Soltwedel, Thomas; Schewe, Ingo

  18. Geochemistry of sediment core PS2456-4

    Spielhagen, Robert F; Siegert, Christine; Erlenkeuser, Helmut
    Sediment core PS2458 from the Laptev Sea continental margin (983-m water depth) stems from a position close to the paleoriver mouth of Lena and Yana rivers. It was dated by AMS-14C and analyzed in high resolution for oxygen isotopes of planktic foraminifers. Except the uppermost 100 cm and possibly the lowermost meter of the 8-m-long core, the sediments were deposited during the last deglaciation (14.5-8.0 cal-ka). According to 210Pb data, the uppermost 100 cm represents only the last 200 years. Planktic foraminifers are present throughout the dated deglacial interval, with the exception of a short time after ca. 13 cal-ka....

  19. Planktonic isotope record and clay mineralogy of sediment core PS2138-1

    Knies, Jochen; Vogt, Christoph
    Improved multiparameter records from the northern Barents Sea margin show two prominent freshwater pulses into the Arctic Ocean during MIS 5 that significantly disturbed the regional oceanic regime and probably affected global climate. Both pulses are associated with major iceberg-rafted debris (IRD) events, revealing intensive iceberg/sea ice melting. The older meltwater pulse occurred near the MIS 5/6 boundary (~131,000 yr ago); its ~2000 year duration and high IRD input accompanied by high illite content suggest a collapse of large-scale Saalian Glaciation in the Arctic Ocean. Movement of this meltwater with the Transpolar Drift current into the Fram Strait probably promoted...

  20. (Table 1) Age/depth fixpoints within MIS 5 in sediment core PS2138-1

    Knies, Jochen; Vogt, Christoph

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