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Very high electrical conductivity beneath the Münchberg Gneiss area in Southern Germany: implications for horizontal transport along shear planes |
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| Authors: | Oliver Ritter Volker Haak Volker Rath Eckardt Stein & Manfred Stiller |
| Institution: | GeoForschungsZentrum, Telegrafenberg, D-14473;Potsdam, Germany. E-mail: -potsdam.de., Technische Universität Berlin, Institut für Angewandte Geophysik, Petrologie und Lagerstättenkunde, Ackerstrasse 71–76, D-13355;Berlin, Germany, Institut für Mineralogie, Technische Universität Darmstadt, Schnittspahnstrasse 9, D-64287;Darmstadt, Germany |
| Abstract: | New magnetotelluric data from the Münchberg Gneiss complex in Southern Germany reveal a zone of extremely high electrical conductivity. 1-D modelling of the data is justified in the period range 0.01 to 10 s. At least three layers are required to explain the steepness of the apparent resistivity curves, and the best-fitting models comprise four layers with successively higher conductivities. The layers of highest conductivity at depths between 2.2 and 3.6 km correlate with pronounced bands of high seismic reflectivity (profile DEKORP 85-4N). The Münchberg complex is today widely recognized as a tectonic klippe, consisting of rocks whose metamorphic and stratigraphic order is inverted rather than overturned. The material was transported into its present position by predominantly horizontal tectonic forces along shear zones. We interpret the high conductivity and high reflectivity as remnants of this transport process. |
| Keywords: | DEKORP85-4N electrical conductivity magnetotellurics Münchberg Gneiss complex shear zones Variscan orogeny |