Electromagnetic measurements in the vicinity of the KTB drill site. Part I: The MV results across a 2-D array

Macro-anisotropy of the electrical conductivity of the crust: a magnetotelluric study of the German Continental Deep Drilling site (KTB)

“…Similar models of mid‐crustal conductive layers with zones of enhanced conductance in an E–W direction were derived for profiles west of the FL (Hofer 1990) and along the Czech–German border (Cerv et al . 1993a).…”

“…The striking feature is the divergence of the curves of the two polarizations towards long periods. In addition, it is seen that at site F101, which is further to the NE on the profile, the splitting of the apparent resistivity curves appears at longer periods (0.1 s) than for to site G106, where curves separate at 0.02 s. Cerv et al . (1993a) found a similar behaviour of the apparent resistivity and phase curves at stations east of the Czech–German border.…”

“…However, the large induction vectors (up to 0.4) may be due to E–W‐striking high‐conductivity structures in the middle crust that terminate the anisotropic upper layer at depth. A number of studies (Eisel 1990; Tauber 1993; ERCEUGT Group 1992; Cerv et al . 1993a) place this layer at about 10 km depth.…”

“…While the FL seems to represent a major boundary in terms of MT impedance responses, a very similar pattern of IV data is observed along profiles west of the FL (Hofer 1990). MT and magnetovariational (MV) measurements along the Czech–German border (Cerv et al . 1993a,b) revealed the same southward orientation of the induction vectors east of the KTB region.…”

“…The 2‐D models derived from the IV data by different authors (Jensen et al . 1988, 1990; Eisel 1990; Tauber 1993; Cerv et al . 1993a) and based on different data sets all incorporate a mid‐crustal layer of enhanced conductivity.…”