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  • 2005-2009  (5)
  • 1990-1994  (4)
  • 1
    In: Marine geology, Amsterdam [u.a.] : Elsevier Science, 1964, 262(2009), Seite 105-115, 1872-6151
    In: volume:262
    In: year:2009
    In: pages:105-115
    Description / Table of Contents: Studying the morphology and subsurface geometry of mud volcanoes provides insights into their activity. This paper describes the internal structure of the Håkon Mosby mud volcano (HMMV) in the southwestern Barents Sea and presents a conceptual model of its evolution. The lack of a mud edifice and the profuse gas flares suggest that in the recent past the mud volcano evolution was predominantly controlled by venting of gas-rich fluids and free gas. However, the analysis of high-resolution single-channel seismic (SCS) data reveals for the first time the existence of a pseudo-mud chamber at the top of the 3 km deep central conduit. It was once created at the seabed and is now a buried expression that acts as mud chamber. The pseudo-mud chamber is situated approximately 300 m below the seafloor, directly above the 330 ka Bear Island Slide (BIS) scar reflection and below glacigenic debris flow deposits that constitute the sediment on top. The sediment profiler data indicates a younger mud deposit above the debris flows, which points to a reactivation of the mud volcano. The reactivation was most likely triggered by the contrast in density between the gas-rich mud chamber and the high-density debris flow deposits. Three stages, i.e. initiation, sealing and reactivation, and a second active period define the evolution of this young mud volcano. Both, the morphology and size of the conduit as well as in-situ temperature gradients point towards a focused and rapid fluid flow.
    Type of Medium: Online Resource
    Pages: graph. Darst
    ISSN: 1872-6151
    Language: English
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  • 2
    ISSN: 1439-0264
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: Subcommissural organ (SCO) secretory activity of the goat (variations of Capra hircus, that live in arid conditions) was examined during the postnatal development, using specific antibodies against the Reissner's fibre (AFRU) and angiotensin II (AAGII). The SCO was strongly stained with the anti-glycoproteins that form the Reissner's fibre and lightly marked with the anti-angiotensin II. The AFRU-immunoreactivity (ir) was found in the ependymal and hypendymal cells and in the ventricular and peripheral secretory routes of the goat SCO. The amount AFRU increases at 6 months and decreases at adult age. In contrast, the anti-angiotensin II-ir was mainly found in the adult age, not being practically observed at one postnatal month. The AAGII-ir was mainly found in ependymal cells in which AFRU-ir was downregulated. In addition, we detected the presence of double immunostained for AFRU and AAGII in ependymocytes of the pre-commissural and subcommissural parts. In conclusion the present results may suggest a functional interrelation between AAGII and the secretory activity of the SCO of this kind of goat.
    Type of Medium: Electronic Resource
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  • 3
    Electronic Resource
    Electronic Resource
    Springer
    Il nuovo cimento della Società Italiana di Fisica 14 (1992), S. 961-975 
    ISSN: 0392-6737
    Keywords: Buoyancy-driven instability ; Non-Newtonian fluid flows ; Nonequilibrium thermodynamics ; irreversible processes
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Summary The possible bifurcations of a convective instability in viscoelastic fluid are studied. The viscoelastic behaviour is modelized by means of the Oldroyd type fluid whose parameters can be adjusted to suit a large class of polymeric fluids. We analyse in some detail bifurcations of codimension one (stationary or oscillatory convection) and codimension two for such kind of fluids. By a weak nonlinear analysis, the coefficients of the amplitude equations corresponding to the different bifurcations are also determined. It has been found that the nature of the convective solution depends crucially on both the viscoelastic parameters and the constitutive equation used to describe the fluid.
    Type of Medium: Electronic Resource
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  • 4
    Electronic Resource
    Electronic Resource
    Springer
    Journal of statistical physics 64 (1991), S. 1045-1058 
    ISSN: 1572-9613
    Keywords: Rayleigh-Bénard convection ; patterns ; defects ; Ginzburg-Landau equation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract The properties of the transition between two patterns with different symmetries are studied in an experiment on thermal convection in a fluid layer heated from below. The defect structure is also analyzed and it is found that the unstable phase is present in the defect cores. The experimental results are in agreement with a model of three coupled Ginzburg-Landau equations.
    Type of Medium: Electronic Resource
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  • 5
    Electronic Resource
    Electronic Resource
    Springer
    The European physical journal 88 (1992), S. 93-94 
    ISSN: 1434-6036
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract We report on spiral type convection patterns obtained from a numerical treatment of a generalized Swift-Hohenberg equation.
    Type of Medium: Electronic Resource
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  • 6
    Electronic Resource
    Electronic Resource
    Springer
    Annali di matematica pura ed applicata 156 (1990), S. 243-251 
    ISSN: 1618-1891
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mathematics
    Notes: Summary In this paper we give several descriptions of padic semi-Fredholm operators in terms of the preservation of orthogonal sequences and compactoid sets.
    Type of Medium: Electronic Resource
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  • 7
    Publication Date: 2012-02-23
    Type: Conference or Workshop Item , NonPeerReviewed
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  • 8
    Publication Date: 2017-08-04
    Description: Studying the morphology and subsurface geometry of mud volcanoes provides insights into their activity. This paper describes the internal structure of the Håkon Mosby mud volcano (HMMV) in the southwestern Barents Sea and presents a conceptual model of its evolution. The lack of a mud edifice and the profuse gas flares suggest that in the recent past the mud volcano evolution was predominantly controlled by venting of gas-rich fluids and free gas. However, the analysis of high-resolution single-channel seismic (SCS) data reveals for the first time the existence of a pseudo-mud chamber at the top of the 3 km deep central conduit. It was once created at the seabed and is now a buried expression that acts as mud chamber. The pseudo-mud chamber is situated approximately 300 m below the seafloor, directly above the 330 ka Bear Island Slide (BIS) scar reflection and below glacigenic debris flow deposits that constitute the sediment on top. The sediment profiler data indicates a younger mud deposit above the debris flows, which points to a reactivation of the mud volcano. The reactivation was most likely triggered by the contrast in density between the gas-rich mud chamber and the high-density debris flow deposits. Three stages, i.e. initiation, sealing and reactivation, and a second active period define the evolution of this young mud volcano. Both, the morphology and size of the conduit as well as in-situ temperature gradients point towards a focused and rapid fluid flow.
    Type: Article , PeerReviewed
    Format: text
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  • 9
    Publication Date: 2020-02-12
    Description: The Gulf of Cadiz is characterized by pervasive mud volcanism. At least thirty mud volcanoes have been identified so far, and it is commonly believed that they result from sediment dewatering enhanced by tectonic forces within the accretionary prism. However, the geological processes that control the location of individual mud volcanoes are poor ly understood, mainly because of the lack of high-quality seismic data in the area. Recently acquired high-resolution 3D seismic data and geochemical sediment cores indicate that halokinesis controls the location of some mud volcanoes. The 3D seismic data at the Mercator Mud Volcano indicate localized development of a slightly asymmetrical anticline that was co ntinuously active for the past 800 ka assuming average sedimentation rates of 0.5 m/ka. The 3D seismic data show that the apex of the anticline is characterised by a rocky sea bed outcrop of unknown lithology, which is underlain by a chaotic seismic facies. The most plausible explanations for these observations is the presence of a salt diapir. This is corroborated by geochemical cores from the Mercator Mud Volcano which show very high chlorinity values of 4.5 mol/l and Na/Cl ratios of 1.0 indicating dissolution of evaporites (halite). Gypsum clasts within the mud volcano sediments are probably xenoliths transported to the surface from a deep source. Linear chlorinity gradients within hemipelagic sediments 220 m away and 50 m above the nearest mud flows indicate a salt source within 100 m suggesting that those particular mud flows have a high salt concentration. Together the seismic and geochemical observations imply that halokinesis is controlling the location of the Mercator Mud Volcano and that its fluid flow system is heavily influenced by the presence of ascending salt. Our observations imply that salt distribution on the northwest African margin extends at least 500 km further northward than previously known, and that petroleum plays for this area have to include the influence of salt. They also imply that halokinesis has to be considered as a driving force for other mud volcanoes in the areas.
    Type: info:eu-repo/semantics/conferenceObject
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