GEOPHYSICAL RESEARCH, 2020, vol. 21, no. 1, pp. 5-23. https://doi.org/10.21455/gr2020.1-1
UDC 550.37; 551.243; 551.254; 551.164
Abstract References Full text (in Russian)
STUDYING OF THE METAMORPHIC STRATUM SUBSURFACE STRUCTURE BY THE GEORADAR METHOD (THE NORTHERN LADOGA REGION)
P.N. Aleksandrov(1), Yu.A. Morozov(2), A.L. Kulakovskij(2), M.A. Matveev(2), A.I. Smulskaya(2), Yu.F. Sokolova(2)
(1) Geoelectromagnetic Research Center of the Schmidt Institute of Physics of the Earth RAS, Moscow, Troitsk, Russia
(2) Schmidt Institute of Physics of the Earth, Russian Academy of Sciences, Moscow, Russia
Abstract. The results of studying the subsurface structure of consolidated metamorphic strata using georadar profiling conducted in the metaterrigeneous Paleoproterozoic Ladoga complex of the southeastern part of the Baltic Shield are presented. In the areas with a detailed study by geological methods of the fractured-folded structure, three methodological problems were solved: 1) the identification of consolidated crystalline rocks of the Ladoga complex under the cover of loose deposits; 2) depth tracking of surface elements of faults and folded structure; 3) an assessment of the possible causes and factors that determine the properties contrast of the rock structure elements visible in radargrams by dielectric constant and/or electrical conductivity. The possibility of determining by georadar method the position of the consolidated rocks surface hidden under loose deposits is shown. A fairly high degree of compliance of the structure mapped on the surface with the style of the structural pictures on the profiles is obtained. Based on the analytical study of the composition of rocks and the processes of their mineral-material transformations during folded and fracture deformations in the profiling areas, the role of a number of structural-material factors in the manifestation of the increased conductivity and dielectric permittivity of some rocks in creating the corresponding section contrast is assessed, which is fundamentally important for interpretation of received radargrams.
Keywords: georadar profiling, electrical conductivity, structure of metamorphic strata, cover-basement system, Northern Ladoga region.
References
Aleksandrov P.N., Teoreticheskie osnovy georadarnogo metoda (The theoretical basis of the georadar method), Moscow: Physmatlit, 2017, 120 p.
Biske N.S., Kolodey V.A., Raman spectroscopy of graphite from deposits and ore occurrences of the Ladoga region, Geology and Minerals of Karelia, 2014, no. 17, pp. 103-109.
Escola P., The problem of mantled gneiss domes, Quart. J. Geol. Soc. London, 1949, vol. 104, pt. 4, pp. 461-476.
Leonov M.G., Morozov Yu.A., Nikitin A.V., Posthumous tectonics and the exhumation mechanisms of exhumation of granitic plutons: the case of the Transbaikal region and the Tien Shan, Geotectonics, 2008, no. 2, pp. 3-31.
Luodes H., Ground penetrating radar and assessment of natural stone. Espoo: Geological Survey of Finland, 2015, 46 p.
Morozov Yu.A., On the role of transpression in the structure formation of the Baltic shield, Geotectonics, 1999, no. 4, pp. 37-51.
Morozov Yu.A., Gaft D.E., On the nature of granite-gneiss domes of the Northern Ladoga, in Structure and Petrology of Precambrian Complexes, Moscow: Institute Physics of the Earth USSR Academy of Sciences, 1985, pp. 3-121.
Morozov Yu.A., Kulakovsky A.L., Matveev M.A., Smulskaya A.I., On vertical structural zoning in a metamorphogenic crust (as exemplified by the Northern Ladoga), in Problems of tectonics of continents and oceans, Moscow: GEOS, 2019, vol. 2, pp. 67-73.
Morozov Yu.A., Matveev M.A., Smulskaya A.I., Kulakovskij A.L., Two genetic types of pseudotachylytes, Doklady Earth Sciences, 2019, vol. 484, pt. 2, pp. 129-133.
Starovoitov A.V. Interpretation of georadar data. Training Manual, Moscow: MSU Publishing, 2008, 192 p.
Velikoslavinsky D.A., Metamorphic zones in the North Ladoga area and temperature estimation of metamorphism of kyanite and andalusite types of regional metamorphism, in Metamorphic belts of the USSR, Leningrad: Nauka, 1971, pp. 61-69.
Vladov M.L., Sudakova M.S., Georadiolokation. From the physical basis to promising direction. Training manual, Moscow: GEOS, 2017, 240 p.