This data collection provides digital access to data and publications of the KTB (German Continental Deep Drilling Program) project. KTB was a very detailed, long-term Earth science investigation on the structure, dynamics and formation of the Central European crust in Northeastern Bavaria, Germany (Harms, Kück 2016). With geophysical sounding and ultra-deep drilling it elucidated a crustal block at the border of a micro-continental collision zones amalgamated during the Caledonian and Variscan orogenies.
Major research themes were: i) the nature of geophysical structures and phenomena, ii) the crustal stress field and the brittle-ductile transition, iii) the thermal structure of the crust, iv) crustal fluids and transport processes, and v) structure and evolution of the central European Variscan basement.
KTB started in 1982 with pre-site selection studies and scientific objective definition followed in 1985 by site selection studies including shallow boreholes. From 1987 to 1990 a pilot borehole of 4000 m depth was drilled and fluid tests and borehole studies were conducted. In 1990 started drilling of a so-called superdeep main borehole of 9101 m depth that was reached in 1994. Again, the final drilling phase was concluded with large-scale fluid and seismic experiments.
The rocks drilled comprise metamorphic series of mafic volcanic, volcano-clastics as well as minor gabbroic to ultramafic rocks that are intercalated with leucocratic meta-sedimentary gneisses. They represent most likely a deeply subducted accretionary wedge mélange with a complex P-T-t history. The undisturbed bottom hole temperature is ~265°C.
Among the outstanding results are the following:
(1) A continuous profile of the complete stress tensor was obtained.
(2) Several lines of evidence indicate that KTB reached the present-day brittle-ductile transition.
(3) The drilled crustal segment is distinguished by large amounts of free fluids down to mid-crustal levels.
(4) The role of post-orogenic brittle deformation had been grossly underestimated.
(5) Steep-angle seismic reflection surveys depict the deformation pattern of the upper crust.
(6) High-resolution seismic images of the crust can be obtained with a newly developed technique of true-amplitude prestack depth migration.
(7) The electrical behavior of the crust is determined by secondary graphite (+/-sulfides) in shear zones. (after Emmermann und Lauterjung (1997)
The dataset presented in this compilation provides the input data used for the geological interpretation and for the model parameterization (Norden et al., 2022) of a 3D seismic survey in the area of the geothermal research platform Groß Schönebeck (carried out in 2017; Krawczyk et al., 2019), focussing on the deep Permo-Carboniferous geothermal targets. The geothermal research platform Groß Schönebeck is located about 50 km north of Berlin, on the southern edge of the Northeast German Basin, and is equipped with two deep wells, the E GrSk 3/90 and Gt GrSk 4/05 boreholes. In this data compilation we provide general data on the location of the boreholes and data on the applied methods and the interpretation of petrophysical properties (density, porosity, permeability, thermal properties) obtained by core analysis and well-log interpretation.
Because cores were available for the E GrSk 3/90 borehole only, most of the data is referring to the borehole that was drilled more or less vertically. The other borehole (Gt GrSk 4/05) is a deviated well, drilled as a geothermal production well. Further on, we provide the main interpreted structural reflector horizons of the geological model from surface to the assumed top of sedimentary Carboniferous (for discussion of the uncertainty of this boundary please consider the comments in Norden et al., 2022) and the horizons and 3D grid properties of a parameterized simulation grid for the deep geothermal target (sedimentary Rotliegend and Permo-Carboniferous volcanic rocks).