Seismic/Pressure/Gravity Magnetics Revisited
Proper two-dimensional and three-dimensional basin modeling relies on accurate seismic processing and interpretation, correct depth conversion of the identified sedimentary layers, reliable modeling of the thermal history of the basin, and understanding of the regional geodynamic setting. Seismic reprocessing using the common reflection surface (CRS) stack technique allows revised interpretation of the structural setting and the evolution of salt plugs in the area of the Glueckstadt Graben, located near the center of the North German Basin (NGB). Reprocessing of seismic data also provides an alternative view of the geodynamic origin of the basin. Reprocessing of data clearly demonstrates the capabilities of the CRS technique to improve the quality of low-fold data. The images display a considerably improved signal-to-noise ratio and much more detail than the common midpoint processing (CMP) of the 1980s. Moreover, a velocity model consistent with the data was built and used to perform prestack and poststack depth migrations. The image of a Jurassic salt plug indicates tectonics similar to observations in the Allertal region at the northern fringe of the inverted Lower Saxony Basin, where overthrusting plays a major role in the evolution of salt structures. Consequently, shortening of the Mesozoic strata was included in the revised interpretation. The reprocessing also provided new insights into the petroleum systems in this area, indicating possible new exploration targets. The results may lead to a new geologic understanding of the area. Instead of a two-story salt plug, steep reverse faults and associated salt structures similar to the features along the Allertal lineament may best explain the investigated seismic line. Furthermore, CRS processing leads to a new view of the shape of the Moho in the center of the NGB. This view supports the assumption that the origin of the NGB may be more related to metamorphic processes during basin initiation than to crustal stretching.