During several student excursions of the FU Berlin, geoelectric investigations were carried out in the SW of the German Continental Deep Drilling (KTB) site across the Franconian Lineament (Fränkische Linie), which separates the sedimentary (Mesozoic) foreland from the crystalline nappe of the Zone Erbendorf-Vohenstrauss (ZEV). A strong negative self- potential anomaly was found to run parallel to the fault zone, reaching values of up to -800mV. A DC-geoelectric sounding was conducted along profile I, displaying a very good shallow conductor. Graphite, perhaps associated with pyrite, is the most plausible explanation for this anomaly (which is also expressed in VLF and Slingram soundings).
Another anomaly of similar dimensions is observed near Großensees.