Results of geophysical researches of the West Timan fault

The territory of the Komi Republic in structural and tectonic terms is a complex intersection node of various structures of different age of the East European platform Volga Ural anteclise, Mezen syneclise, Timan, Pechora syneclise, and the Northern Urals. The West Timan deep fault is considered to be the boundary of the Russian and Pechora plates. The West Timan deep fault is a boundary between the Epicarelian Russian and Epibaikal Timan Pechora plates, extending over 800 km. The fault is expressed by an overthrust, where the Riphean of the Timan Pechora plate is pushed over the Russian plate. According to seismic data, it is established that the jointing occurs along the foldthrust zone bounded by the West Timan and Central Timan faults, the distance between which varies widely.The southern and middle segments of the West Timan fault are considered. Based on the materials of potential fields, various areas of the West Timan fault can be identified in the study area: the southern part (Beloborsk block), the central part (Nivshera block), the northern part (Sindor block). Beloborsk block: the axial part of the regional minimum of the gravitational field, the axial part of the minimum of the magnetic field. Nivshera block: the boundary area between two gravitational minima, the axial part of the maximum of the magnetic field. Sindor block: the inflection zone of positive values of the gravitational field, the gradient zone between positive and negative values of the magnetic field.Based on the interpretation of seismic materials, the location of the West Timan fault was clarified. The nature of the seismic recording does not always allow to identify the exact location of the displacers, only the difference in the recording in individual blocks is clearly marked. The boundary area sometimes covers 5 km.Within the study area, six pedestrian magnetic exploration profiles were worked out. “Beloborsk”, “Ozyag”, “Troitsk”, “Nivshera”, “Meshchura”, “Sedyudorsk”, passing through different parts of the West Timan fault. Summarizing the detailed magnetic investigation, it can be said that the West Timan fault in the magnetic field cannot be traced by a clear zone, both in the gradient sections of the field and within the regional maxima and minima. In some cases, it can only be traced over a series of dikes of basic and ultrabasic rocks, but they may not be located in the frontal fault zone. Express radon survey across the West Timan fault was carried out along nine profiles that cross the West Timan fault: Beloborsk, Ust Nem, Ust Kulom, Ozyag, Troitsk, Nivshera, Sindor, "Meshchura", "Sedyudor" (from South to North).According to the results of Express emanation survey, it is noted that the West Timan fault in the study area is characterized by increased VRA values that vary in the range of 400 2150 Bq/m3.The average VRA values of the Beloborsk block are 500 Bq/m3, Nivshera 400 Bq/m3, Sindor 300 Bq/m3. The maximum concentration of radon in the soil air was registered in the Nivshera block.ity of radon of the Beloborsk block is KQ = 2.6, Nivshera block KQ = 2.8, Sindor block KQ (south) = 2.0, KQ (north) = 5.6. The West Timan fault is also characterized by the variability of radon activity in both longitudinal and transverse directions.Thus, with insufficient seismic study and low differentiation of potential fields, the emanation radon survey can be used as an additional method for detecting and tracing tectonic disturbances. In practical terms, attention should be paid to the Sindor block, where a sharp gradient area is marked in the magnetic field, against which a series of dikes stands out. This zone is also characterized by a high KQ.