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Publication . Article . 2010

Tomographic P wave velocity and vertical velocity gradient structure across the geothermal site Groß Schönebeck (NE German Basin): Relationship to lithology, salt tectonics, and thermal regime

Klaus Bauer; Inga Moeck; Ben Norden; Alexander Schulze; Michael E Weber; Holger Wirth;
Open Access
Published: 25 Aug 2010
Country: Germany
[1] Seismic wide-angle data were collected along a 40-km-long profile centered at the geothermal research well GrSk 3/90 in the Northeast German Basin. Tomographic inversion of travel time data provided a velocity and a vertical velocity gradient model, indicative of Cenozoic to Pre-Permian sediments. Wide-angle reflections are modeled and interpreted as top Zechstein and top Pre-Permian. Changes in velocity gradients are interpreted as the transition from mechanical to chemical compaction at 2–3 km depth, and localized salt structures are imaged, suggesting a previously unknown salt pillow in the southern part of the seismic profile. The Zechstein salt shows decreased velocities in the adjacent salt pillows compared to the salt lows, which is confirmed by sonic log data. This decrease in velocity could be explained by the mobilization of less dense salt, which moved and formed the salt pillows, whereas the denser salt remained in place at the salt lows. We interpret a narrow subvertical low-velocity zone under the salt pillow at GrSk 3/90 as a fault in the deep Permian to Pre-Permian. This WNW-ESE trending fault influenced the location of the salt tectonics and led to the formation of a fault-bounded graben in the Rotliegend sandstones with optimal mechanical conditions for geothermal production. Thermal modeling showed that salt pillows are related to chimney effects, a decrease in temperature, and increasing velocity. The assumed variations in salt lithology, density, and strain must thus be even higher to compensate for the temperature effect.
Subjects by Vocabulary

Microsoft Academic Graph classification: Graben Inversion (geology) Sedimentary rock Geology Petrology Mineralogy Evaporite Lithology Fault (geology) geography.geographical_feature_category geography Geothermal gradient Salt tectonics


Institut für Erd- und Umweltwissenschaften, Paleontology, Space and Planetary Science, Earth and Planetary Sciences (miscellaneous), Atmospheric Science, Earth-Surface Processes, Geochemistry and Petrology, Soil Science, Water Science and Technology, Ecology, Aquatic Science, Forestry, Oceanography, Geophysics, 550 - Earth sciences