Deep seismic reflectivity patterns in specific tectonic units of Western and Central Europe

Abstract

SUMMARY A systematic comparative study of the reflectivity of the continental crust is undertaken—made possible by the expanded data basis of deep seismic reflection profiles in Europe. The reflectivity is not at all the same but can change dramatically from one seismic line to the next. Different seismic reflectivity patterns—independent of applied techniques—are observed. Correlations between these seismic patterns and specific tectonic units can be found. While lamellae and bands of reflections in the lower crust are widespread in post‐orogenic extensional areas, ‘crocodiles’ seem to represent compressional zones that are occasionally accompanied by seismic duplex structures. The ‘fishbone’ pattern—many ‘minicrocodiles’—is characteristic for the old London‐Brabant Massif. The ‘ramp and flat’ structure displays the thin‐skinned tectonics of the North Variscan Deformation Front over a length of 2000 km. Diffraction clusters in the lower crust accompanied by a dipping reflection in the upper crust can be observed close to thick‐skinned deformation fronts. Diffractions are also present in rift areas, for example in the North Sea. Some regions show a decreasing reflectivity with depth. The reflections are concentrated in the upper crust and no Moho reflections can be observed. These areas can be correlated to areas with Precambrian crust.

Fine crustal structure and deformation beneath the Great Xing’an Ranges, CAOB: Revealed by deep seismic reflection profile

“…The fact that the continental crust exhibits significant differences in reflectivity has been observed from the collected seismic data (Sadowiak et al, 1991). These large scale differences are independent of data acquisition and processing parameters (Trappe et al, 1988).…”

Results of the DEKORP 1 (BELCORP-DEKORP) deep seismic reflection studies in the western part of the Rhenish Massif

“…The concept of the London-Brabant Massif as an old block with poor reflectivity is supported by two more observations: one is the general observation that old shields are thicker than young crusts and often less reflective (Meissner & Wever 1989;Sadowiak, Wever & Meissner 1991). The other is the generally poor reflectivity of the BELCORP line (Bouckaert, Fock & Vandenberghe 1988), which lies in the centre of the London-Brabant Massif and shows only short diffuse reflections with varying dips and low strength (Meissner 1989).…”

Adaptation of seismic skeletonization for other geoscience applications

“…To this end, mapping the event or discontinuity structure along with a seismic attribute analysis (Taner et al 1972) is routinely done on reflection seismic data in seismic industry. In some cases, statistical methods (Sadowiak et al 1991; Trappe et al 1988) are applied to understand the reflectivity patterns. Present 2‐D grid skeletonization yields both the event map and some of its attributes.…”