Reprocessed deep seismic reflection profile DEKORP 1988-9N across the Northern Upper Rhine Graben, Southwest Germany

Abstract

The profile 9N was recorded in 1988 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 lower 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. (2019). The profile 9N was 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 improved considerably compared to the 1990‘s, a state-of-the-art reprocessing was implemented. In comparison with the original processing (Stiller et al. (2019), 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 reprocessed DEKORP-9N survey comprises all datasets newly achieved in addition to the datasets from the original processing (Stiller et al. (2019)), i.e. (1) as unstacked data the raw data, the CRS processed data and the migrated image gathers, and (2) as stacked data the pure CRS stack, the poststack-time as well as prestack-time and prestack-depth migrated sections. Moreover, (3) all velocity models used for the different versions including (4) the separate first-break tomography inversion as well as (5) several attribute analyses (RMS amplitude, instantaneous frequency and phase, Q-factor and others) 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 9 survey was shot across the Tertiary Upper Rhine Graben, which intersects both the Saxothuringian and Moldanubian regions obliquely. Since the Eocene the Rhine Graben represents an active rift system. The 92 km long, E-W trending DEKORP'88-9N profile crosses the northern part of the Upper Rhine Graben. It starts in the crystalline Odenwald, crosses the Tertiary and Quarternary fill of the Rhine Graben and ends in the late Palaeozoic sequences of the Saar-Nahe Basin in the west. There it crosses the Permian rhyolitic Donnersberg intrusion.

The DEKORP'88-9N profile is of particular interest to investigate the seismic resolution of the base of the cenozoic graben fill, the prolongation of faults in the sediments of the Northern Upper Rhine Graben, the transition to the crystalline Odenwald at the eastern border fault, the transition to the Saar-Nahe basin in the west and the transition from the crystalline Odenwald to the Buntsandstein Odenwald in the east of the profile. The additional attribute analyses were carried out to possibly detect previously unknown faults or fracture zones.

The seismic sections of 9N show different crustal structures on both sides of the graben and some indications of dipping reflections in the mantle on the western side, which could refer to the genesis of the Upper Rhine Graben. An important new feature is the presence of a Permo-Triassic layer in the Upper Rhine Graben, which is significantly thicker than previously mapped (> 600 m) and thus the upper edge of the basement is situated over 600 m deeper than in the original data.

The reprocessing of the DEKORP'88-9N profile was funded by the HLNUG in cooperation with the Agency for Geology and Mining of the state of Rhineland-Palatinate.

Additional Information

The German Continental Seismic Reflection Program DEKORP (DEutsches KOntinentales Reflexionsseismisches Programm) was carried out between 1984 - 1997 and funded by the Federal Ministry of Education, Science and Technology (BMFT), now Federal Ministry of Education and Science (BMBF). The data was originally processed in the DEKORP Processing Centre (DPC) at the Institute of Geophysics of the Technical University Clausthal. DEKORP was founded in 1983 with the aim to investigate the deep crustal structure of Germany with high-resolution near-vertical incidence seismic methods. It was closely associated with the deep drilling project KTB (German continental deep-drilling program). One of the main research topics of DEKORP were deep seismic studies to investigate the lithospheric structure beneath Germany. The DEKORP profiles cover approx. 450 km in the state of Hesse and mostly cross areas for which there is only insufficient geological data (i.e. only few deep boreholes).

As a governmental agency the HLNUG archives and publishes the data for future applications and usages, such as the search for a repository for nuclear waste in Germany, an expansion of the geophysical database, possibilities for modelling using gravimetric and magnetic data as well as an improvement of the 3D underground model of the state of Hesse. Therefore, the results are directly linked to the new geological 3D model of the state of Hesse, developed by the Technical University of Darmstadt (Hessen3D 2.0 project, BMWi-FKZ: 0325944).

The reprocessed DEKORP datasets provide up-to-date unique and deep insights into the subsurface below Germany covering the earth’s crust from the surface to the upper mantle. Fields of applications are geothermal development, hazard analysis, hydrocarbon/shale gas exploration, underground gas storage, tunnel construction and much more.

Authors

• Homuth, Benjamin;HLNUG Hessian Agency of Nature Conservation, Environment and Geology, Wiesbaden, Germany
• Stiller, Manfred;GFZ German Research Centre for Geosciences, Potsdam, Germany
• Schmidt, Bernd;Landesamt für Geologie und Bergbau Rheinland Pfalz, Mainz, Germany

Contact

• Stiller, Manfred; GFZ German Research Centre for Geosciences, Potsdam, Germany; ➦
• Homuth, Benjamin; HLNUG Hessian Agency of Nature Conservation, Environment and Geology, Wiesbaden, Germany; ➦
• Schmidt, Bernd; Landesamt für Geologie und Bergbau Rheinland Pfalz, Mainz, Germany; ➦

Contributors

Bär, Kristian; Weinert, Sebastian; Agafonova, Tatiana; Kaerger, Lauretta; DMT Petrologic GmbH & Co. KG

Keywords

DEKORP, Deutsches Kontinentales Reflexionsseismisches Programm, deep crustal structures, crustal-scale seismic survey, near-vertical incidence seismic reflection, Vibroseis acquisition, reprocessing, CRS processing, prestack migration, attribute analyses, Northern Upper Rhine Graben, Variscan orogenic belts, Odenwald, Saar-Nahe Basin, rift system, Mohorovičić discontinuity, sedimentary graben fill, geothermal resources, seismic risks

GCMD Science Keywords

• EARTH SCIENCE > SOLID EARTH > TECTONICS > EARTHQUAKES > SEISMIC PROFILE
• EARTH SCIENCE > SOLID EARTH > TECTONICS > PLATE TECTONICS
• In Situ/Laboratory Instruments > Profilers/Sounders > SEISMIC REFLECTION PROFILERS