Geology & Geochemistry of Combustible Minerals No. 1–2 (189–190) 2023, 26–40
Ihor KUROVETS, Ihor HRYTSYK, Oleksandr PRYKHODKO, Pavlo CHEPUSENKO, Stepan MYKHALCHUK, Svitlana MELNYCHUK, Roman-Danylo KUCHERInstitute of Geology and Geochemistry of Combustible Minerals of National Academy of Sciences of Ukraine, Lviv, Ukraine, e-mail: email@example.com
An analysis was made as to the usage of geological-geophysical methods for studying of low-amplitude tectonic dislocations in coal-enclosing massifs. As a result of geophysical researches conducted at coal fields, mine fields and mine workings of the Lviv-Volyn Coal Basin, the methods of field observations by means of natural electromagnetic and electric fields were worked and their results were processed for prediction and diagnostics of tectonic dislocations with a break of continuity and zones of unstressed state. To raise the efficiency of the methods of electromagnetic fields it is recommended to carry out measurements at wide frequency range (from 5 to 50 hz) with orientation of the antenna according to the world sides (azimuthal surveying) and at narrow frequency range (5; 12.5; 17 khz) with the southern orientation of the antenna (frequency sensing). According to azimuthal surveying one can calculate the vector of maximum intensity of electromagnetic radiation. It was ascertained that over distinctive dislocation one can observe the variation in the direction and absolute value of vectors. Displacement of the anomaly of electromagnetic radiation intensity at different frequency range by profile indicates the direction of dipping of the area of displacement of dislocations with a break of continuity. The method of natural electromagnetic impulse field of the Earth fixes both the dislocations, distinguishes by geological-geophysical methods before, and new low-amplitude dislocations and stressed zones.Tectonic dislocations, that are displayed only in Paleozoic deposits, are distinguished by contrast anomalies of electromagnetic radiation in electromagnetic field, but dislocations with a break of continuity that cut the Mesozoic thickness and in most cases are accompanied by zones of rock fracturing in the Cretaceous deposits: by wide destructive anomalies. Plots over worked-out lavas with stressed deformational state are characterized by strongly differential abnormal values of the intensity of natural impulse electromagnetic field of the Earth. The method of natural electric field allows us to detect zones with water-bearing fracturing rocks in the upper part of the geological section. Methods of natural impulse electromagnetic field of the Earth and natural electric field may be used both independently and in the complex with other geophysical methods for detection and tracing of tectonic dislocations and dynamically-unstressed zones. Thus, the optimum apparatus-methodical complex for detection and diagnostics of low-amplitude dislocations with a break of continuity of coal-enclosing series by electromagnetic methods (NIEMF, NEF) was formed and effective methods of field observations, processinf and interpretation of data were developed.
low-amplitude tectonics, natural electric field, impulse electromagnetic field of the Earth, coal-bearing rocks, geophysical profiles
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