ACCOUNTING THE EFFECT OF TERRAIN RELIEF DURING AEROMAGNETIC SURVEYING WITHIN LARGE MAGMATIC PROVINCES

(Dolgal A.S. Muravina O.M. Krivolutskaya N.A. Ponomarenko I.A. )

The problem of taking into account the influence of a sharply dissected relief of the earth’s surface during aeromagnetic surveys carried out in areas of intense magmatism is considered. The factors that have a significant effect on the accuracy of magnetic field reduction are listed. An original method is presented for assessing the influence of the upper part of the geological section, composed of intensely magnetized rocks, on the results of field observations. The method uses the decomposition of digital data on the magnetic field and elevations into empirical mode functions, followed by applying to the obtained components of the method of group accounting of arguments. The results of the reduction of medium-scale aeromagnetic survey in Eastern Siberia are presented.......

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  • 2020  № 4, pp. 2-8

BOREHOLE MAGNETOMETRY IN THE STUDY OF THE URAL SUPERDEEP BOREHOLE

(Igolkina G.V. )

Magnetometry studies of the superdeep well of the Ural SG-4 allowed us to obtain data on magnetic fields, magnetization and magnetic susceptibility of rocks at great depths in natural occurrence. The study of the magnetic properties of tuffs and tuffites revealed the relationship of magnetic parameters with their structural and textural features. Studies have made it possible to determine the spatial position of the magnetic bodies illuminated by the well, to calculate their elements of occurrence. It is established that the use of well magnetometry increases the reliability of structural constructions according to geological data and makes possible deep structural forecast.......

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  • 2020  № 4, pp. 9-15

CAPABILITIES OFFERED BY VSP WHEN PROCESSING AND INTERPRETING ONSHORE 2D/3D SEISMIC DATA

(Lensky V.A. Irkabaev D.R. Zhuzhel A.S. )

The fact that VSP is playing an increasingly bigger role during land seismic data processing and interpretation can be explained by the need to reach a new level of data processing and interpretation with more precise and detailed geological results. This level cannot be attained without accounting for certain aspects of wavefield imaging, evaluating its relationship with a geological medium and monitoring how this relationship changes during the processing stage. The methodology of such studies is only now beginning to be developed and capabilities offered by VSP are still not fully addressed by geophysicists working with seismic data. This paper looks at the most pertinent problems that can be solved through VSP to improve the quality of both processing and interpretation of land seismic data. A number of problems requires the elaboration of specialized techniques and practices of borehole observations involving different modifications, including VSP 2D and VSP 3D. The efficiency of utilising VSP data increases with a greater density of studied wells drilled within a seismic survey area. By analysing data areally, we can establish a relationship between variations in velocity characteristics as well as properties of reflections and variations in depositional environments, more thoroughly control the quality of land seismic data processing and substantiate the best possible criteria for structural and dynamic interpretation, which may vary across different parts of the survey area.......

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  • 2020  № 4, pp. 16-24

GPR AS A PROSPECTIVE METHOD FOR STUDYING THE RITMICAL STRUCTURE OF QUATERNARY DEPOSITS (FOR EXAMPLE, SAISARY LAKE IN YAKUTSK)

(Neradovskii L.G. )

The spectral analysis of GPR signals recorded on Saisary lake in Yakutsk was performed. Three periodic generations of time series of pulses were detected in the GPR signals. According to drilling data of the support well, they correspond to three rhythmic structures of sediments of different genesis. According to the drilling of the reference borehole, they correspond to three rhythmic structures of sedimentary deposits of different genesis. In silt-peat deposits and clay deposits of lake-swamp genesis with a thin- layer rhythmic structure to a depth of 2,0 m pulses follow each other with periods 0,41-0,20-0,15 m. In the transitional zone with the appearance of sandy material in lake-swamp deposits, the period of pulses repetition at the depth of 2,0-3,4 m increases to 0,67-0,34-0,22 m. Below 3,4 m, where the basal sandy thickness of alluvial genesis begins with thick-layer rhythmic structure of sands of different grains, the pulse period reaches the maximum values 0,84-0,43-0,31 m. The GPR method is recommended for use in permafrost studies in order to solve stratigraphy problems, as a promising auxiliary tool for rapid and non-destructive study of the rhythmic structures of Quaternary deposits.......

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  • 2020  № 4, pp. 25-33

THE RESULTS OF EXPERIMENTAL AND METHODOLOGICAL SURVEYS OF ELECTRICAL PROSPECTING AT THE SITE OF THE MSU IN ALEXANDROVKA (KALUGA REGION)

(Kulikov V.A. Ermolin E.Y. Melnikov A.V. Asoskov A.E. Polikarpova V.A. )

The results of experimental and methodological surveys which were conducted in the spring of 2019 at the “Alexandrovka”, the scientific and educational geophysical base of the Geological Faculty of Lomonosov Moscow State University in the Kaluga region is presented in the article. The testing work included several tasks. One of them consisted in comparing the results of measurements of induced polarization (IP) carried out in the time domain with the registration of the total decay of the IP field, with the results of frequency domain measurements by using the differential phase parameter (DPP). The question of the applicability of the empirical formula A.V. Kulikov (Kulikov A.V., 1978) for the calculation of DPP into apparent polarizability was raised repeatedly by many geophysicists, and this question remains open. The second task of the experimental surveys was to compare the results of geometric soundings performed with different arrays along the profile. At the last stage, along the profile, audiomagnetotellurics measurements were performed by using MTU-5A equipment and a joint inversion of the audiomagnetotellurics data and electrotomography data was applied. The result was compared with a priori geological information that is available for the area of the scientific and educational base.......

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  • 2020  № 4, pp. 34-42
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