Abstract
A comprehensive analysis by the methods of natural electromagnetic fields, earthquake converted waves, and deep seismic sounding provided detailed constraints on the section of the crust and sedimentary cover in Ciscaucasia and revealed areas of the maximum crustal permeability on the Scythian plate and suture and underthrusting zones in the North Caucasus fold system. Based on seismic and electric evidence, the connected porosity is estimated at 1.5–3%, with the background value being smaller than 0.1%. These junction zones of the Scythian plate and fold block structures of the Main Caucasus Ridge are characterized by a decrease in the electrical resistivity by more than an order of magnitude, a more than fivefold drop in converted wave amplitudes, and a decrease in the converted and longitudinal wave velocities by up to 6%.
This is a preview of subscription content, log in via an institution to check access.
Similar content being viewed by others
References
Atlas of North Caucasus Maps (1:1000000): Tectonic Map of the North Caucasus, Map of Residual Gravity Anomalies, Map of Magnetic Anomalies, and Service Map of North Caucasus Combustible Minerals, Ed. by N. I. Prutskii (Severo-Kavkazskii Regional’nyi Geol. Tsentr MPR Rossii, GUP, and “Tsentral’naya Geologo-S” emochnaya Ekspeditsiya,” Essentuki, 1998) [in Russian].
K. Bahr, “Geological Noise in Magnetotelluric Data: A Classification of Distortion Types,” Phys. Earth Planet Int. 66, 24–38 (1991).
M. L. Bazhenov and V. S. Burtman, Structural Arcs of the Carpathians-Caucasus-Pamirs Alpine Belt (Nauka, Moscow, 1990) [in Russian].
V. V. Belyavsky, “Invariant Curves of Magnetotelluric Sounding,” Geofiz. Zh. 20(5), 99–104 (1998).
V. V. Belyavsky, “Multiplicative Analysis of Magnetotelluric Data Measured on the Krasnaya Polyana Profile (the North Caucasus),” Razved. Okhr. Nedr, No. 4, 28–37 (2004).
V. V. Belyavsky, V. A. Bobrov, S. V. Goshovskii, et al., Geoelectric Models of Auriferous Deposits of the Ukrainian Shield and Donbass, Ed. by V. V. Belyavsky (Znannya, Kiev, 2004) [in Russian].
O. A. Bogatikov, Yu. V. Nechaev, and A. L. Sobisevich, “Cosmic Technologies in the Study of Geological Structures of Elbrus Volcano,” in Tectonics and Geodynamics of the Continental Lithosphere. Proc. XXXVI Tectonic Conf. (Geos, Moscow, 2003), Vol. 1, pp. 44–48 [in Russian].
T. G. Caldwell, H. M. Bibby, and C. Brown, “The Magnetotelluric Phase Tensor,” Geophys. J. Int. 158, 457–469 (2004).
J. L. Counil, J. L. le Mouel, and M. Menvielle, “Associate and Conjugate Directions Concepts in Magnetotellurics,” Ann. Geophys. 2(4), 115–130 (1986).
V. Druskin and L. Knizhnerman, “Spectral Approach to Solving Three-Dimensional Maxwell’s Diffusion Equations in the Time and Frequency Domains,” Radio Sci. 29(4), 937–953 (1994).
A. V. Egorkin, “Crustal Structure from Seismic Geotraverse Data,” in Deep Structure of the USSR Territory, Ed. by V. V. Belousov, N. I. Pavlenkova, and T. N. Kvyatkovskaya (Moscow, 1991), pp. 118–134 [in Russian].
A. V. Egorkin, V. V. Kun, and N. M. Chernyshev, “Attenuation of P and S Waves in the Crust and Upper Mantle of the West Siberian Plate,” Izv. Akad. Nauk SSSR, Ser. Fiz. Zemli, No. 2, 37–50 (1981).
Geoelectric Model of the Tectonosphere of the Eurasian Fold Belt and Adjacent Territories, Ed. by V. V. Belyavsky and S. N. Kulik (Znannya, Kiev, 1998) [in Russian].
V. V. Gordienko, “Implications of Deep Geoelectric Data for the Assessment of Tectogenesis Hypotheses,” Fiz. Zemli, No. 10, 54–63 (2002) [Izvestiya, Phys. Solid Earth 38, 846–854 (2002)].
G. V. Krasnopevtseva, Deep Structure of the Seismically Active Caucasus Region (Nauka, Moscow, 1984) [in Russian].
L. E. Levin and N. V. Kondorskaya, “Seismicity of the Central Mediterranean Belt of Eurasia in Relation to the Development of the Oil and Gas Complex,” Razved. Okhr. Nedr, No. 2, 28–31 (1998).
Seismically Active Fluid-Magmatic Systems of the North Caucasus, Ed. by N. P. Laverov (IFZ RAN, Moscow, 2005) [in Russian].
T. I. Shankland and H. S. Waff, “Partial Melting and Electrical Conductivity Anomalies in the Upper Mantle,” J. Geophys. Res. 33, 5409–5417 (1977).
A. G. Shempelev, V. Ya. P’yankov, V. A. Lygin, et al., “Geophysical Results from the Near-Elbrus Profile (Elbrus Volcano-Kavkazskie Mineralnye Vody),” Region. Geol. Metallogeniya, No. 25, 178–185 (2005).
Tectonic Layering of the Lithosphere and Regional Geological Studies, Ed. by Yu. M. Pushcharovskii (Nauka, Moscow, 1990) [in Russian].
L. L. Vanyan and N. I. Pavlenkova, “Low Velocity and Low Electrical Resistivity Layer at the Base of the Upper Crust under the Baltic Shield,” Fiz. Zemli, No. 1, 37–45 (2002) [Izvestiya, Phys. Solid Earth 38, 33–41 (2002)].
I. M. Varentsov, “A General Approach to the Magnetotelluric Data Inversion in a Piecewise-Continuous Medium,” Fiz. Zemli, No. 11, 11–33 (2002) [Izvestiya, Phys. Solid Earth 38, 913–934 (2002)].
B. G. Voblikov and A. F. Lopatin, “Tectonic Structure of Paleozoic Deposits in the Central and Eastern Ciscaucasia,” in Tectonics and Geodynamics (Stavropol, 2002), pp. 87–108 [in Russian].
M. R. J. Wyllie, A. R. Gregory, and L. W. Gardner, “Elastic Wave Velocities in Heterogeneous and Porous Media,” Geophysics 21, 41–70 (1956).
P. Zhang, R. G. Roberts, and L. B. Pedersen, “Magnetotelluric Strike Rules,” Geophysics 52, 267–277 (1987).
Author information
Authors and Affiliations
Additional information
Original Russian Text © V.V. Belyavsky, A.V. Egorkin, L.N. Solodilov, V.A. Rakitov, A.G. Yakovlev, 2007, published in Fizika Zemli, 2007, No. 4, pp. 4–14.
Rights and permissions
About this article
Cite this article
Belyavsky, V.V., Egorkin, A.V., Solodilov, L.N. et al. Some results of applying methods of natural electromagnetic and seismic fields in the North Caucasus. Izv., Phys. Solid Earth 43, 268–277 (2007). https://doi.org/10.1134/S1069351307040027
Received:
Issue Date:
DOI: https://doi.org/10.1134/S1069351307040027