Research Drilling Bayerhof (Bavaria)

In the vicinity of the German continental deep drilling (KTB, Upper Palatinate) single sediment deposits of Tertiary age are known. In the data set of the 3D-seismics, the Integrated Seismic Oberpfalz from 1989 (ISO89), these structures cause seismic travel time anomalies and are imaged by increased thicknesses of the weathering layer. Also in the area of the research drilling Bayerhof seismic velocities of about 1900 m/s indicate sediment deposits. 

The research drilling Bayerhof, that was performed in October / November 2000 by the Bavarian Geological Survey (Bayerisches Geologisches Landesamt)  and reached a final depth of 178 m, revealed limnic sediments until 153 m depth. Geophysical downhole measurements in the research drilling Bayerhof confirmed the lithostratigraphic and structural classification of the Tertiary beds, which consist of peat and lignite layers, and laminated lake sediments. Within the section of the lake sediments beside low densities, magnetic susceptibilities, and seismic velocities being typical for maar sediments especially the increasing content of uranium with anomalies up to 60 ppm is obvious. A detailed gravimetric survey above the Bayerhof structure confirmed the negative gravity anomaly that was expected already due to the drilling results. The diameter of the maar structure is about 450 m. 

K-Ar datings of basaltic tuff breccias and basalts from the vicinity of the maar done by cooperation between the Bavarian Geological Survey and the Institute for Mineralogy, Munich University, revealed an eruption age between 23.3 and 21.7 Ma before present.