Th geochemistry of radioactive elements was examined in the Kuznetsk, Minusinsk, Tunguska, and Gorlovo Paleozoic coal basins in Siberia. Quantitative analytical techniques (INAA, delayed neutron analysis, and XRF) were used to study 2600 samples of coals and their host rocks. The average U and Th concentrations in the coals are 2 and 3 ppm, respectively. The lateral and vertical variability of the distribution of radioactive elements was examined on the scale of coal basins, deposits, and individual coal seams. It was deterinined that elevated U and Th concentrations in coals are often related to rock blocks enriched in radioactive elements in the surroundings of the basins or are correlated with volcanic activity during coal accumulation. High concentrations of these elements in coal seams are restricted to zones near the tops of the seams and the soil zones, the boundaries of partings, or to beds enriched in pyroclastic material. Using the f-radiography method, it was determined that the main mechanism of U accumulation in coals is its sorption on the organic matter. Thorium is contained in both the mineral and the organic constituents of coals. An increase in the ash contents of coals with clarke radioactivity is associated with an increase in the contents of U and Th in the mineral matter.
|Состояние||Опубликовано - мая 2005|
ASJC Scopus subject areas
- Geochemistry and Petrology