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  • 2015-2019  (3)
  • 1995-1999  (2)
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  • 1
    Electronic Resource
    Electronic Resource
    Power Spectra Analysis of Aeromagnetic Data and KTB Susceptibility Logs, and their Implication for Fractal Behavior of Crustal Magnetization (1998)
    Springer
    Pure and applied geophysics 151 (1998), S. 147-159 
    Details
    ISSN: 1420-9136
    Keywords: Key words: Magnetic anomaly, power spectrum, fractal parameter.
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences , Physics
    Notes: Abstract. —Power spectra analysis of aeromagnetic data from the southeast North Sea, where the depth to the top of the magnetic sources is reasonably well constrained, indicates that the scaling factor or spectral exponent (β) in an area with thick sediment cover is likely to be significantly different from the expected value of -3. This is consistent with the results from analyzing the KTB susceptibility data, which show that the magnetic scaling factor changes with burial depth. For sources shallower than about 1 km, a β value of -2.3 is roughly consistent with previous similar investigations. For sources deeper than a few kilometers, the β value could be as low as -1.0. Therefore, the depth estimation using power spectra analysis of magnetic data should be treated with caution, especially if there is no independent constraint on the source depth or the scaling factor (for instance from susceptibility logs in boreholes).
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s000240050109
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    Paper (German National Licenses)
    Fulltext
  • 2
    Electronic Resource
    Electronic Resource
    Deep Structure of the Swiss Alps: Results of NRP 20. O.A. Pfiffner, P. Lehner, P. Heitzmann, St. Mueller, and A. Steck (editors). (1998)
    Springer
    Surveys in geophysics 19 (1998), S. 207-209 
    Details
    ISSN: 1573-0956
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences , Physics
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1006582025632
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    Paper (German National Licenses)
    Fulltext
  • 3
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    Unknown
    The crustal structure in the transition zone between the western and eastern Barents Sea (2018)
    Wiley
    In:  Geophysical Journal International, 214 (1). pp. 315-330.
    Details
    Publication Date: 2021-02-08
    Description: We present a crustal-scale seismic profile in the Barents Sea based on new data. Wide-angle seismic data were recorded along a 600 km long profile at 38 ocean bottom seismometer and 52 onshore station locations. The modeling uses the joint refraction/reflection tomography approach where co-located multi-channel seismic reflection data constrain the sedimentary structure. Further, forward gravity modeling is based on the seismic model. We also calculate net regional erosion based on the calculated shallow velocity structure. Our model reveals a complex crustal structure of the Baltic Shield to Barents shelf transition zone, as well as strong structural variability on the shelf itself. We document large volumes of pre-Carboniferous sedimentary strata in the transition zone which reach a total thickness of 10 km. A high-velocity crustal domain found below the Varanger Peninsula likely represents an independent crustal block. Large lower crustal bodies with very high velocity and density below the Varanger Peninsula and the Fedynsky High are interpreted as underplated material that may have fed mafic dykes in the Devonian. We speculate that these lower crustal bodies are linked to the Devonian rifting processes in the East European Craton, or belonging to the integral part of the Timanides, as observed onshore in the Pechora Basin.
    Type: Article , PeerReviewed
    Format: text
    DOI: 10.1093/gji/ggy139
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    OceanRep: Article in a Scientific Journal - peer-reviewed
  • 4
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    Unknown
    Seismic explosion sources on an ice cap – technical considerations (2015)
    Elsevier
    In:  Polar Science, 9 (1). pp. 107-118.
    Details
    Publication Date: 2017-05-01
    Description: Controlled source seismic investigation of crustal structure below ice covers is an emerging technique. We have recently conducted an explosive refraction/wide-angle reflection seismic experiment on the ice cap in east-central Greenland. The data-quality is high for all shot points and a full crustal model can be modelled. A crucial challenge for applying the technique is to control the sources. Here, we present data that describe the efficiency of explosive sources in the ice cover. Analysis of the data shows, that the ice cap traps a significant amount of energy, which is observed as a strong ice wave. The ice cap leads to low transmission of energy into the crust such that charges need be larger than in conventional onshore experiments to obtain reliable seismic signals. The strong reflection coefficient at the base of the ice generates strong multiples which may mask for secondary phases. This effect may be crucial for acquisition of reflection seismic profiles on ice caps. Our experience shows that it is essential to use optimum depth for the charges and to seal the boreholes carefully.
    Type: Article , PeerReviewed
    Format: text
    Format: text
    DOI: 10.1016/j.polar.2014.11.002
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    OceanRep: Article in a Scientific Journal - peer-reviewed
  • 5
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    Unknown
    Crustal composition of the Møre Margin and compilation of a conjugate Atlantic margin transect (2016)
    Elsevier
    In:  Tectonophysics, 666 . pp. 144-157.
    Details
    Publication Date: 2019-09-24
    Description: Highlights • The basement at the mid-Norwegian Møre Margin is dominantly felsic in composition. • A lower crustal body is interpreted as a mixture of continental blocks and eclogite. • The thickness of the outer lower crustal body is twice as thick on the East Greenland Margin. • The thinning during this first phase of post-Caledonian extension was highest for proto Norway. Abstract The inner part of the volcanic, passive Møre Margin, mid-Norway, expresses an unusual abrupt thinning from high onshore topography with a thick crust to an offshore basin with thin crystalline crust. Previous P-wave modeling of wide-angle seismic data revealed the presence of a high-velocity (7.7–8.0 km/s) body in the lower crust in this transitional region. These velocities are too high to be readily interpreted as Early Cenozoic intrusions, a model often invoked to explain lower crustal high-velocity bodies in the region. We present a Vp/Vs model, derived from the modeling of wide-angle seismic data, acquired by use of Ocean Bottom Seismograph horizontal components. The modeling suggests dominantly felsic composition of the crust. An average Vp/Vs value for the lower crustal body is modeled at 1.77, which is compatible with a mixture of continental blocks and Caledonian eclogites. The results are compiled with earlier results into a transect extending from onshore Norway to onshore Greenland. Back-stripping of the transect to Early Cenozoic indicates asymmetric conjugate magmatism related to the continental break-up. Further back-stripping to the time when most of the Caledonian mountain range had collapsed indicates that the thinning during the first phase of extension was about 25% higher for proto Norway than proto Greenland.
    Type: Article , PeerReviewed
    Format: text
    DOI: 10.1016/j.tecto.2015.11.002
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    OceanRep: Article in a Scientific Journal - peer-reviewed
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