Local radon anomaly in the Vychegda-Lokchim fault zone

When mapping fault zones of the Vychegda trough radon survey was conducted. The Vychegda- Lokchim, Pritiman, Keltmin, and Vishera faults were investigated. The Vychegda-Lokchim fault is located in the southwestern part of the Vychegda trough and is the borderline with the Kirov- Kazhim aulacogen. Emanation studies across the Vychegda-Lokchim fault were carried out in its northern and central sections. High values of the volume radon activity were observed in the course of research near the village of Chetdino. In this regard, we carried out additional work to localize the radon anomaly. Monitoring of radon activity was performed in summer and autumn for 3 days. Maximum values of the volume radon activity in the central part of the anomalous region reached12750 Bq/m3, minimum - 3300 Bq/m3. Measure-ments of volume radon activity in air give values of 35-130 Bq/m3. These values were compared with the indications of volume activity of the ra-dium industry near the settlement Vodny. As a result, the scheme of isolines of the anomalous radon zone was constructed. The anomaly has an elongated shape, located in the direction close to the strike of the Vychegda-Lokchim fault.Further detailed study of the "Chetdinskaya" anomalous zone is recommended, using the entire available complex of geophysical and geochemical methods.