Magnetics of North Germany

This project looks at the spatial resolution and accuracy of regional anomaly data. These have increased considerably in recent decades, particularly with respect to aeromagnetic surveys. Based on two case studies, we have compared older measurements from aerial surveys carried out by Prakla-Seismos between 1965 and 1971, with a modern aerial survey carried out by Sander Geophysics in 2005 to look at information content in the short-wave range.

Findings

  • Short-wavelength anomalies (smaller than 5 km) exist in both datasets. In addition to more accurate positioning, the resolution of the anomalies is also better in the modern data.
  • Short-wavelength anomalies are associated with stratigraphic boundaries and where formations crop out on the surface. This correlates with well-known geology (e.g. outcrops of base Upper Cretaceous/Jurassic).
  • Field samples and samples from cores confirm the details in the literature: the total magnetisation in the upper Lower Cretaceous can be as high as 0.15 A/m. The remnant magnetisation of the rocks from the lower Upper Cretaceous (so-called 'Trümmererze') is roughly parallel to the present-day geomagnetic field.
  • 3D models of a salt dome as well as of a Jurassic outcrop provide good explanations for the observed anomalies in both surveys, after introducing a thin, higher magnetised horizon in the upper Lower Cretaceous, and/or higher magnetisation in the Upper Jurassic.
  • The stratigraphic interpretation of shallow lithologies can be improved by taking magnetic anomalies into consideration.

Project-relevant literature:

  • On the use of small amplitude magnetic anomalies for the improvement of geological models: case studies from Northern Germany. - Zeitschrift der Deutschen Gesellschaft für Geowissenschaften, 167(2-3): 131-148; DOI: 10.1127/zdgg/2016/0064.
    2016, SKIBA, P., GABRIEL, G., KRAWCZYK, C.M., KÖNIG, M., BÜCKER, C. & ROLF, C.

Project Management

Dr. Gerald Gabriel

Prof. Dr. Charlotte Krawczyk (now at GFZ)

Project Scientist

Peter Skiba

Duration

2010-2011

Funding

Dea Deutsche Erdöl AG

Partner

Dea Deutsche Erdöl AG
(Dr. C. Bücker, Dr. M. König)