THE DEEP TENSOR CSMT SOUNDING WITH INDUSTRIAL POWER LINES AT THE EASTERN PART OF THE FENNOSCANDIAN (BALTIC) SHIELD (FENICS EXPERIMENT)

An international experiment FENICS (Fennoscandian electrical conductivity from results of soundings with Natural and Controlled Sources) on the deep tensor electromagnetic sounding of the Fennoscandian (Baltic) shield has been carried out at the summer 2007. According to data analysis the maximal distance of signals registration reached to 1300 km (observatory Barentsburg). The uniform primary database of the FENICS experiment is in progress. For the data treatment the program of synchronous spectral analysis of current and measured signals is developed. The programs of the forward and inversion problems solution for the deep soundings with taking into account the influence from ionosphere and displacement currents are developed. The inversion problem is solved on the basis of bimodal scheme with taking into account both (NS and EW) polarizations of the primary source. By results of tensor sounding the parameters of a "normal" geoelectrical section of the lithosphere are specified. On the basis of the experiment "FENICS" data it is made the preliminary modeling of the tectonic and physical conditions in lithosphere of the Fennoscandian (Baltic) shield at the transition zone "crust-mantle" and constructed the scheme of location of the low boundary of the "cold" lithosphere. Connected to the data, the boundary between pseudo-brittle and ductile conditions of substance is studied.