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EVAREST

The EVAREST project − Evaluation of residual fields from the joint modelling of potential field data − is concerned with the evaluation of structural models at depths of 0.5 − 5 km by jointly considering gravimetric and magnetic anomalies using 3D forward modelling. The aim was to enhance the reliability of the interpretation. The area of investigation (38 km x 32 km) was in north Germany.

Findings

  • The main sources of the gravity anomalies are at depths of 0.5 to 5 km.
  • The sources of the magnetic field anomalies are divided into two groups: a) long-wave anomalies, primarily caused by deep crustal structures and b) short-wave anomalies with amplitudes that correspond to the order of magnitude of the data accuracy.
  • The joint interpretation of gravimetric and magnetic anomalies provides additional information on the geology of the area of investigation, which can help improve the structural models.
  • The gravimetric model requires the implementation of density gradients or larger changes in geometry. The magnetic model reveals that thin magnetised horizons can enable the maximum depths of the sources of local anomalies to be estimated.
  • Density gradients are associated with considerable variations within the individual horizons, but can still provide new information on geological developments within the region. Larger changes in geometry would necessitate a critical examination of the seismic interpretation.
  • Filtered data confirm that the salt dome rim-synclines often give rise to local magnetic anomalies. The joint consideration of gravimetric and magnetic anomalies in this case improves the existing structural model.
[Translate to Englisch:] Modelle Gravimetrie und Magnetik
Forward modelling of band-pass filtered, gravimetric and magnetic anomalies. Left: gravimetric model with density variations defined by a depth-dependent function via a Voxel-Cube (colour-coded). The best results are produced with a fixed geometry. Right: magnetic model, with identical geometry, in which all horizons down to the Lower Cretaceous reveal moderate susceptibilities.

Project Management

Dr. Gerald Gabriel

Project scientist

Peter Skiba

Duration

2012-2013

Funding

RWE Dea and LIAG

Partner

RWE Dea
(Dr. C. Bücker, Dr. M. König)