Deep seismic reflection profile DEKORP 1984-2S across the Franconian Platform, South Germany

DEKORP 2S was the first profile carried out in 1984 as part of the DEKORP project, the German deep seismic reflection program. The seismic line has a length of 250 km and was the first and only DEKORP line to be acquired using explosives as source energy. The objectives of the experiment were to explore the deep crustal structure of the Saxothuringian Zone and of its transitions into the adjacent Moldanubian and Rhenohercynian Zones of the Variscan Belt, to obtain evidence about vertical tectonic processes during the Variscan orogenesis, to understand the causes of observed gravity and magnetic anomalies and to recognize and define the Variscan front to the north. In addition, the survey contributed to the International Lithosphere Program (ILP) and the former European Geotraverse (EGT). Details of the experiment, preliminary results and interpretations may be obtained from DEKORP Research Group (1985) or Meissner et al. (1987). The Technical Report of line 2S gives complete information about acquisition and processing parameters. The European Variscides, extending from the French Central Massif to the East European Platform, originated during the collision between Gondwana and Baltica in the Late Palaeozoic. Due to involvement of various crustal blocks in the orogenesis, the mountain belt is subdivided into distinct zones. The external fold-and-thrust belts of the Rhenohercynian and Saxothuringian as well as the predominantly crystalline body of the Moldanubian dominate the central European segment of the Variscides. Polyphase tectonic deformation, magmatism and metamorphic processes led to a complex interlinking between the units. The SE-NW striking DEKORP 2S line runs perpendicular to the Variscan strike direction and crosses the tectonic boundaries between the Moldanubian, Saxothuringian and Rhenohercynian units, which are predominantly covered by Permian and younger sediments (DEKORP Research Group, 1985). Extending from the Danube river to the Taunus Mountains line 2S crosses the Franconian Platform passing through the Noerdlinger Ries, where the impact excavated crystalline basement slivers of the Moldanubian zone, the Spessart Mountains, a part of the Mid German Crystalline High and the NE trending Hessian Through (DEKORP Research Group, 1985). Ending beyond the northeast branch of the Rhine Graben within the Taunus Mountains the profile is extended by line 2N to the northwest.

The German Continental Seismic Reflection Program DEKORP (DEutsches KOntinentales Reflexionsseismisches Programm) was carried out between 1984 – 1999 as the German national reflection seismic program funded by the Federal Ministry of Research and Technology (BMFT), Bonn [now: the Federal Ministry of Education and Research (BMBF)]. DEKORP was administrated by the former Geological Survey of Lower Saxony (NLfB), Hannover [now: the State Authority for Mining, Energy and Geology (LBEG)]. In 1994 the DEKORP management was taken over by the Helmholtz Centre Potsdam GFZ German Research Centre for Geosciences. The aim of DEKORP was to investigate the deep crustal structure of Germany with high-resolution near-vertical incidence (mostly vibro)seismic acquisition, supplemented by wide-angle seismic and other target-oriented piggy-back experiments, all complemented by optimized methods of data processing and interpretation. The DEKORP project was closely linked with the KTB (German continental deep-drilling program) and was an equivalent to many other deep-seismic programs world-wide such as COCORP, BIRPS, LITHOPROBE, ECORS, CROP, BELCORP, IBERSEIS and many more. The DEKORP-Atlas (Meissner & Bortfeld, 1990) gives a detailed overview about most of the different campaigns and results. In sum, the resulting DEKORP database includes approximately 40 crustal-scale 2D-seismic reflection lines covering a total of ca. 4 700 km and one 3D-seismic reflection survey covering ca. 400 km². Each DEKORP survey is provided with all datasets that are necessary for either a re-processing (i.e. raw unstacked field records in SEGY) or a re-interpretation (i.e. finally processed sections in SEGY or PNG). The raw data are sorted by records or by CDPs. The final data are available as unmigrated or migrated stacks without or with coherency enhancement. Automatical line-drawings are also included. All data come with additional meta information for each domain (source, receiver, CDP) like coordinates, elevations, locations and static corrections combined in ASCII-tables for geometry assignment. Furthermore, all metadata originating from paper copies are made available as scanned files in PNG or PDF, e.g. field and observer reports, location maps in different scales, near-surface profile headers and others. The DEKORP datasets provide unique and deep insights into the subsurface below Germany covering the earth’s crust from the surface to the upper mantle and are increasingly requested by academic institutions and commercial companies. Fields of applications are geothermal development, hazard analysis, hydrocarbon/shale gas exploration, underground gas storage, tunnel construction and much more.