аномалії електропровідності conductivity anomalies 3D geoelectric model MT/MV methods Ukrainian Shield electrical conductivity anomalies geoelectromagnetic methods magnetotelluric sounding вуглеводні геоелектромагнітні методи 3D geoelectrical model 3D геоелектрична модель 3D геоэлектрическая модель Brusyliv fault zone Golovanivsky suture zone Kerch iron ore basi Zvizdal-Zaliska fault zone anomalies of conductivity anomalies of electrical conductivity anomalies of electro-conductivity anomalies of electroconductivity asthenosphere crust deep and audiomagnetotelluric sounding deep structure electromagnetic research experimental electromagnetic studies fault zones fluidization hydrocarbons