Three-dimensional electromagnetic modeling of the Trans-European Suture Zone (EMTESZ 3-D)

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During the EMTESZ project (Electromagnetic Study of the Trans-European Suture Zone) several magnetotelluric (MT) transects across the Northeast German and the Polish Basin were realized. They were interpreted in a two-dimensional (2-D) manner, and this is certainly justified for most of the data in the NE German – S Swedish part of the study area. In the central part of the Polish Basin, however, a clear indication for three-dimensionality, mainly from induction vectors exists: real vectors at long periods point predominantly perpendicular to the profiles. Thus 2-D modeling can only be regarded as a first step in interpretation, which may even yield a false image of conductivity structures at depth. In the meanwhile, 3-D inversion codes have become more accessible and computing performance (considering memory and execution time) allows now for more realistic model geometries. It is thus an objective of this proposal to apply such – freely available – codes to the data set, particularly to the inverted basin area of the Czaplinek block and salt dome. We expect to get a clearer image of the highly conductive zone – interpreted as an alum shale layer – in the basin, and particularly of the good conductor in the uppermost mantle. 3-D conductance studies will complement this approach. The 3-D inversion will principally be carried out by our Polish project partners with close interaction/guidance from our side and in cooperation with the Russian partners, who will supply the conductance maps of the entire study area. Keywords: Trans-European Suture Zone, electromagnetics, 3-D conductivity models, 3-D inversion