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Abstract

The high reflectivity of the upper and middle crust of the Oberpfalz, both for near vertical and wide-angle reflections, was one reason for selecting this area as site for the German Continental Deep Drilling Program KTB. A peculiarity in the middle crust beneath the KTB site is the so-called Erbendorf-Body (EB) giving rise to extremely strong wide-angle reflections. It deserves special interest because its position right on the border between the Saxothuringian and Moldanubian zones of the Vari scan fold belt, the unusual high p-wave velocities (over 7.0 km/s) in its lower part at 11 to 14 km depth, and associated dipping reflectors suggest a possible lower crustal origin of the EB. A specially designed and so far unique wide-angle 3D-survey was carried out as part of the program "Integrated Seismics Oberpfalz 89" for investigating the spatial extent, the velocity distribution and the internal structure of the EB. The first results show clearly that the EB ist not a local phenomenon beneath the DEKORP4 line, but that it exists, yet with remarkable complexities, beneath the whole covered area between the Franconian Line and the Falkenberg granite complex. The wide-angle shots were also recorded by four 3-component geophones in the KTB pilot hole at 3195 to 3295 m depth and provided convincing evidence for s-wave splitting in the upper crust SE of the KTB location. This anisotropy effect seems to be related to the overall strike and dip of rock foliation in the zone of Erbendorf-VohenstrauB (ZEV).