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1 Acta Geophysica Polonica

1 2002

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Electrical conductivity anomalies in the crust and upper mantle of the Ukraine

Kulik S., Burakhovich T., Khazan Y.

Acta Geophysica Polonica

2002

Vol. 50, nr 4

547-565

A wide range of tectonic structures exists on the territory of the Ukraine. Observations of geomagnetic induction vectors revealed anomalously high conductivity of many of them. A quasi-3D geoelectrical model of the Earth's crust and upper mantle of the Ukraine is based upon a thin-sheet approximation inside a regional cross-section of the electric conductivity. As the initial data we used induction vectors measured over the whole Ukrainian territory (about 2500 measurement points) for periods of geomagnetic variations ranging from 150 up to 2000 seconds. After removing the influence of the known distribution of the subsurface conductance (sediments), the residual vectors have been analyzed as being caused by the Earth's crust and upper mantle sources. The model demonstrates that values of the local conductance reduced to thin-sheets range from 0.5 to 20 kS in the Earth's crust and from 2 to 6 kS in the upper mantle. Both, the nature and the origin, of these high conductivity zones are different for different regions. Some possibilities including a contribution of the percolation process in two-phase media are discussed.