International Journal of Earth Sciences

, Volume 98, Issue 3, pp 571–583 | Cite as

Intrusion versus inversion—a 3D density model of the southern rim of the Northwest German Basin

  • Filiz Bilgili
  • Hans-Jürgen Götze
  • Roman Pašteka
  • Sabine Schmidt
  • Ron Hackney
Original Paper

Abstract

An unsolved problem of regional importance for both the evolution and structure of the Northwest German Basin is the existence or non-existence of the so-called Bramsche Massif. Explaining the nature of this massif and the cause of a related strong, positive Bouguer anomaly (Bramsche Anomaly) is critical. In the study described here, we tested an existing “intrusion model” against a newer “inversion model” in the southern Northwest German Basin. In the intrusion model, the strongly-positive Bouguer anomaly represents the gravity effect of an intrusion at depths between 6 and 10 km. More recent interpretations invoke tectonic inversion rather than intrusion to explain increased burial and the low level of hydrocarbon maturity found in boreholes. We tested these different interpretations by constructing 3D forward density models to 15 km depth. The intrusion model was updated and adjusted to incorporate recent data and we also modelled pre-Zechstein structures using different scenarios. The final model has a very good fit between measured and modelled gravity fields. Based on currently available seismic and structural models, as well as borehole density measurements, we show that the positive Bouguer anomaly cannot be modeled without a high-density, intrusive-like body at depth. However, further in-sight into the crustal structures of the Bramsche region requires more detailed investigations.

Keywords

3D gravity modelling Bramsche anomaly Geotectonic Atlas Northwest German Basin Geoinformation system 

Supplementary material

531_2007_267_MOESM1_ESM.tif (17.5 mb)
Fig. A-1: Model I. Left: Map view of measured and modelled Bouguer gravity. Right: statistics for the difference between measured and modelled gravity. The upper part shows a map of the differences between the measured and the calculated anomaly (residual map) and the lower part shows a histogram of these differences, their standard deviation (6.91×10-5 m/s2) and the correlation coefficient between both fields (0.67). (TIF 17.5 mb)
531_2007_267_MOESM2_ESM.tif (2.7 mb)
Fig. A-2: Model II. Left: Map view of measured and modelled Bouguer gravity. Right: statistics for difference between measured and modelled gravity (residual map, histogram, correlation coefficient of 0.55, standard deviation of 7.85×10-5 m/s2). (TIF 2.73 mb)
531_2007_267_MOESM3_ESM.tif (2.7 mb)
Fig. A-3: Model III. Left: Map view of measured and modelled Bouguer gravity. Right: statistics for difference between measured and modelled gravity (residual map, histogram, correlation coefficient of 0.85 and standard deviation of 4.85×10-5 m/s2). (TIF 2.74 mb)

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Copyright information

© Springer-Verlag 2007

Authors and Affiliations

  • Filiz Bilgili
    • 1
  • Hans-Jürgen Götze
    • 1
  • Roman Pašteka
    • 2
  • Sabine Schmidt
    • 1
  • Ron Hackney
    • 1
  1. 1.Department of GeophysicsUniversity Kiel, Inst. for GeosiencesKielGermany
  2. 2.Department of Applied and Environmental GeophysicsComenius UniversityBratislavaGermany

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