The profile 2S was recorded in 1984 as part of the DEKORP project, the German deep seismic reflection program. The focus of the DEKORP project was on deep crustal and lithospheric structures and therefore originally not on structures at shallower depths. From today's perspective, however, this depth range is of great interest for a wide range of possible technical applications (including medium-depth and deep geothermal projects). The original data is published by Stiller et al. (2020). The northernmost 50 km of the 250 km long profile 2S were reprocessed on behalf of the Hessian Agency of Nature Conservation, Environment and Geology (HLNUG). The focus of the reprocessing was on improving the resolution / mapping of geological structures down to a depth of 6 km (approx. 3 s TWT) to describe the prolongation of faults and geological structures in more detail than in previous studies.
In order to achieve these goals and in view of the fact that today's processing and evaluation methods have been improved considerably compared to the 1990‘s, a state-of-the-art reprocessing was implemented. In comparison with the original processing (Stiller et al. (2020)), more sophisticated processing steps like CRS (Common Reflection Surface) instead of CDP (Common Depth Point) stacking, turning-ray tomography and prestack time and depth migration were carried out.
The reprocessing results of the DEKORP 2S survey comprise all datasets newly achieved in addition to the datasets from the original processing (Stiller et al. (2020)), i.e. (1) the migrated CRS image gathers as unstacked data, and (2) the pure CRS stack, the poststack-time as well as prestack-time and prestack-depth migrated sections as stacked data. Moreover, (3) all velocity models used for the different versions including (4) the separate first-break tomography inversion, are contained.
All reprocessed data come in SEGY trace format, the final sections additionally in PDF graphic format. A reprocessing report is included as well as again all meta information for each domain (source, receiver, CDP) like coordinates, elevations, locations and static corrections combined in ASCII-tables for geometry assignment purposes.
The DEKORP 2 survey, consisting of the three segments 86-2Q, 86-2N and 84-2S, starts in the sub-Variscan foredeep of the Münsterland Basin and ends in the Moldanubian region at the Danube. The central part crosses the Rhenish Massif (Rhenohercynian), the Spessart Mountains of the Mid-German Crystalline High (Saxothuringian) and the meteorite impact location of the "Nördlinger Ries". DEKORP '84-2S, was the first DEKORP line and the only one which mainly used explosives as the seismic source. The 250 km long, SE-NW striking profile extends from the Rhenohercynian Taunus Mountains to the Danube thereby crossing the Spessart Mountains, the Hessian Trough and the "Nördlinger Ries". The profile DEKORP 2S is the southern continuation of DEKORP 2N, which intersects at profile km 246.08. The reprocessed datasets contain a sub-section of the entire 2S profile with a total length of 50 km of full CDP fold, covering the profile’s northern part through the state of Hesse.
The DEKORP '84-2S profile is of particular interest to investigate the seismic resolution of the Rhenohercynian Taunus Mountains including the Taunus ridge, as well as the Tertiary Hessian Trough, the Permian Wetterau nappe and a small part of the crystalline Spessart Mountains.
The seismic sections of 2S show clearly visible, predominantly SE-dipping reflectors indicating flat-and-ramp tectonics and a differentiation into a highly reflective lower crust and a less reflective upper crust. Due to the use of explosive shots with relatively large spacing as the seismic source, less new information could be achieved for the uppermost crust compared to the original processing and to other DEKORP (vibroseis) surveys. A clear Moho reflection is visible throughout the whole profile section at a depth of ca. 26 to 28 km.
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.