Geochemistry of radioactive elements (U, Th) in coal and peat of northern Asia (Siberia, Russian Far East, Kazakhstan, and Mongolia)

Geochemistry of radioactive elements in more than 5000 coal and peat samples of Northern Asia has been investigated by quantitative methods, such as the instrumental neutron-activation analysis, the method of delayed neutrons, and the X-ray-fluorescence analysis. The average U content in the coals of deposits and basins of the region ranges from 0.6 to 32.8 ppm and, for Th, from 0.8 to 9.2 ppm. Within the boundaries of basins, deposits and some coal beds lateral and vertical changes of the distribution of radioactive elements have been studied. The high concentrations of U and Th in coal deposits are spatially related to rock blocks within the basin frames, which are enriched in elements, or are connected with a volcanism of a period of coal formation. A consistent changing of the role of pyroclastic material in the radioactive elements accumulation was determined in the direction from the West to the East. (C) 2011 Elsevier B.V. All rights reserved.