Geoelectrical structure across the Bohemian Massif and the transition zone to the West Carpathians

Abstract

Geoelectrical methods of magnetotelluric (MT) and geomagnetic deep soundings (GDS) were employed to infer the electrical conductivity structure at depths of specific regions of the Bohemian Massif (BM) and in the transition zone between the BM and the West Carpathians (WCP). Transfer functions between components of temporal variations of the natural electromagnetic field induced in the Earth by external sources were estimated and converted to electrical conductivity (resistivity) profiles. While the results from other regions of the BM are noted in references, the emphasis here is placed on the new analysis of MT/GDS data at field stations along the regional almost 500-km long Deep Seismic Sounding profile No. VI traversing the country from NW to SE. Inversion of its results suggests a complex geoelectrical structure, characteristic for each geological unit, with layers of increased electrical conductivity at crustal and uppermost mantle depths. The results also indicate strong fields of anomalous induction marking geoelectrical inhomogeneities at the eastern margin of the BM and in the foreland of the WCP.