An integrative 3-D model of the deep lithospheric structure beneath Dolsk and Odra fault zones as a result of magnetotelluric data interpretation

Abstract

SUMMARY Long-period magnetotelluric soundings were carried out in the eastern part of the Fore-Sudetic Monocline in central Europe to determine the deep geoelectrical structure. It is an important area in the contact zone of the Palaeozoic terranes of Western Europe and the Proterozoic East European Craton. The research area includes the Dolsk fault zone and the Odra fault zone, which are essential geological boundaries of a regional nature separating crustal blocks of various origins. There were conducted 51 soundings on the quasi-regular mesh 150 km in SE and 225 km in NE. The research region is highly urbanized, and hence some of the data were strongly disturbed. Careful processing of data was required, and sometimes measurements had to be repeated at other locations. The collected data allow constructing 3-D models of the electrical conductivity distribution. A parallel version of the ModEM 3-D inversion code was used for modelling. The information contained in each used transfer function was also examined by performing a separate inversion of these functions. The obtained resistivity distribution models confirm the Dolsk and Odra faults' location as postulated previously by geologists. They also show that these very deep faults are reaching the lower crust. However, they do not clearly state how far the contemporary lowering of the Baltica reaches under cover of younger Palaeozoic sediments.