Radioactive elements in sediments and altered rocks of the Kikhpinych long-lived volcanic center

Abstract

Data on the concentration of radioactive elements in mineral sediments and hydrothermally altered rocks of the long-lived Kikhpinych volcanic center are presented. High concentrations of uranium (up to 31 g/t) and thorium (up to 46 g/t) relative to the average values for the dacites of Kamchatka and the Uzon-Geyser depression are found in white kaolinite clays of mud pots and in dacites of the Yuzhnoe Kikhpinych thermal field transformed into kaolinite clays. In this field and in the Severnoe thermal field (in the crater of Staryi Kikhpinych Volcano) high values of volume radon activity (VA Rn > 1000 kBq/m3) were recorded in subsoil air. These high concentrations of uranium and thorium in fresh mineral sediments and anomalous values of VA Rn in subsoil air of hydrothermally altered rocks are considered to have resulted from the mass transfer of radioactive elements by fluid flows of the hydrothermal system.