Radiometric and seismic study of Chidvinskaya kimberlite pipe (Arkhangelsk diamondiferous province, North of the East European Craton, Russia)

Abstract

Surface geophysical measurements were carried out on Chidvinskaya diamond pipe of the Arkhangelsk diamondiferous province (North of the East European Craton, Russia). Geophysical measurements included a high-precision gamma-spectrometric survey, radon emanation survey in soil air, and microseismic sounding method. Radiometric measurements were used to found radioactivity anomalies of the surface layer over the Chidvinskaya pipe which could be a result of impact of the kimberlite body on a host medium. Deep structure of the kimberlite pipe and host medium was imaged by means of microseismic sounding method. Results indicate that the pipe appears as a high-velocity body. The host medium is low-velocity that is typical for rocks with excessive fissuring. Increased values of total gamma-ray radiation of near surface layer are observed within the pipe contour and exceeded the background values by 2-4 times. Anomalous radon emanation in the soil air was found at the pipe boundaries. According to the microseismic sounding data near-contact zone is a gas-penetrable structure with excessive fissuring. The results of the used methods are in good agreement with each other. The proposed complex of methods has allowed to identify the pipe distinctive feature.