Electrical resistivity tomography to investigate geological structures of the earth's upper crust |
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| Authors: | Storz Storz & Jacobs |
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| Institution: | Institute of Geophysics and Geology, University of Leipzig, Talstrasse 35, D-04103 Leipzig, Germany.,; HGN Hydrogeologie GmbH, Niederlassung Torgau, PO Box 1330, D-04853 Torgau, Germany. E-mail: |
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| Abstract: | It is important to have detailed knowledge of the electrical properties of the earth's crust in order to recognize geological structures and to understand tectonic processes. In the area surrounding the German Continental Deep Drilling Project (KTB), we have used DC dipole–dipole soundings to investigate the electrical conductivity distribution down to a depth of several kilometres. We have adapted the electrical resistivity tomography (ERT) technique, a well-established near-surface method, to large-scale experiments. Independent transmitting and receiving units were used to realize the concept of simultaneous multichannel registration of the scalar electrical potential at 44 dipoles. The measured data yielded apparent resistivities which were inverted to a 2D resistivity model ranging from the surface down to a depth of 4 km. Two highly conductive structures with steep inclination were detected. They are expected to be major fault zones embedded in a metamorphic body. The rather low resistivity ( ρ < 10 Ωm) can be explained by the existence of graphitic minerals and/or electrolytic fluids. |
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