Patterns of manifestation of faults of the Pechora-Kolvinsky aulacogen in the radon field

Abstract

The article presents results of an express radon survey on the territory of the Pechora-Kozhvinsky and Kolvinsky megswells, which are part of the Pechora-Kolvinsky aulacogen. Radon studies were carried out along profiles across the large structure-forming faults, identified on the basis of seismic data. The results show that faults in the radon field correspond to areas with increased values of the radon volumetric activity. In the course of radon studies, main patterns of the manifestation of faults in the radon field were established. The faults may correspond to the maxima of volume activity of radon against the background of low values or to zones with a minimum concentration of radon. In addition, areas with abnormal radon concentrations not associated with known fractures were identified. The systems faults are characterized by wider radon anomalies or alternation of maxima and minima of radon volumetric activity along the profile. The maximum radon concentration is recorded in the fault zones that are closest to the surface, as well as in faults along which large amplitudes of vertical displacements are noted. Similar levels of radon concentration are observed within the normal faults and thrust faults, covered by sedimentary rocks. Most of the studied faults, according to the relative indicator of radon activity, belong to the group of high radon activity. The concentration of radon in the soil air within the faults varies both in the transverse and longitudinal directions. In some areas, the radon volumetric activity of at the same level at different times. This proves the existence of a constant radon flux. The main factors affecting the formation, transport to the surface, and accumulation of radon in the soil are the composition and depth of the basement, the internal structure of fault zones, the degree of porosity and fracturing of rocks and modern geodynamics of the region. Thus, radon survey as an additional method to other geophysical methods can be used to map faults and identify various blocks that differ in fluid-geochemical features.