A magnetotelluric profile across the German Deep Drilling Project (KTB) area: Two- and three-dimensional modeling results

Previous interpretations of magnetotelluric data from the vicinity of the G erman Deep Drilling Project (KTB) revealed two major structures: a midcrust al layer of increased conductivity and large, regional extent and a highly anisotropic upper crust. Nevertheless, a satisfactory combination of both s tructures explaining all measurements has not yet been achieved, mostly due to incomplete and qualitatively poor data. Simplified superposition of bot h structures could not yield an explanation of the observations. On the bas is of a carefully processed new data set we apply different modeling approa ches to verify the existence of both structures. Models calculated with a t wo-dimensional modeling program, which allows for general anisotropy, as we ll as a full three-dimensional code show that an anisotropic upper crust is overlaying a regional cast-west striking high-conductivity structure. Neve rtheless, this continuous conductive midcrustal layer with a conductance de creasing from north to south must be replaced by a quasi-anisotropic one, a t least in the region of the KTB. The final model may still be oversimplifi ed, considering the complexity of the true but unknown geology in this part icular area, but it demonstrates which major electrically effective structu res could be resolved.