DOI: 10.5880/gfz.dekorp-4n.001
title: Deep seismic reflection profile DEKORP 1985-4N from the Bavarian Forest up to the Franconian Forest, Southeast Germany

description: The 187 km long line 4N was recorded in 1985 as part of the DEKORP project, the German continental seismic reflection program, and served as a basis for a network of six seismic reflection lines KTB 8501 – 8506, which were performed to investigate the planned target area for the Continental Deep Drilling Program (KTB) in the Upper Palatinate. The aim of the survey 4N was to explore the crustal structure of the central Mid-European Variscides down to the Moho and the uppermost mantle with high-fold near-vertical incidence vibroseis acquisition and, in particular, to scan the suture between the Moldanubian Zone and the northward adjacent Saxothuringian Zone. Details of the experiment, first results and interpretations were published by DEKORP Research Group (1987, 1988). The Technical Report of line 4N 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 Saxothuringian represents the infill of a Cambro-Ordovician basin. The Moldanubian contains blocks of pre-Variscan crust and their Palaezoic cover. During the Variscan orogeny the Moldanubian crust was thrust towards the NW over the Saxothuringian foreland. Both units were welded together by a low-pressure metamorphism accompanied by polyphase deformation (DEKORP Research Group, 1987, 1988). The SE-NW striking line 4N runs along the western border of the Bohemian Massif perpendicular to the main tectonic trend (SW-NE). The profile starts in the Bavarian Forest and runs across the Upper Palatinate Forest. Shortly before the NE-trending Erbendorf Line, which separates the Moldanubian unit from the Saxothuringian unit, the profile runs through the area of the KTB drill site. In the Saxothuringian DEKORP 4N runs through the Fichtel Mountains, the Muenchberg Gneiss Complex and ends in the Franconian Forest. In the Bavarian Forest the line 4N traverses DEKORP 4Q nearly perpendicularly. Farther northwest the profile crosses KTB 8501 – 8503, which were arranged parallel to strike of the orogenic belt, as well as the DEKORP 3-D survey ISO 1989 around the KTB drill hole. In the Muenchberg Gneiss Complex the 4N profile is intersected by DEKORP 3B/MVE (East), which runs along the southern margin of the Saxothuringian belt in a SW-NE direction.
description: 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: Federal Ministry of Education and Research BMBF). DEKORP was administrated by the former Geological Survey of Lower Saxony (NLfB), Hanover (now: 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. Automatically 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.