MINERALOGY AND GEOCHEMISTRY OF TONSTEINS IN THE BEYSK COAL DEPOSIT OF THE MINUSINSK COAL BASIN

The relevance of the research is determined by the necessity for assessment of volcanic pyroclastic material impact on formation of geochemical background of rare elements in coal. The main aim is to study the mineralogical and geochemical features of tonsteins and enclosing coals of chernogorskaya suite in the Beysk coal deposit (Minusinsk coal basin). Objects of the research are tonsteins and enclosing coals of chernogorskaya suite in the Beysk coal deposit (Minusinsk coal basin). Methods: sampling of coal seams of chernogorskaya suite in the Beysk coal deposit; chemical composition is estimated with inductively coupled plasma mass-spectrometry, instrumental neutron activation analysis, x-ray fluorescence methods; mineral composition is defined with optical microscopy, petrographic analysis, scanning electron microscopy, x-ray diffractometry. Results. The paper studies mineralogical and geochemical characteristics of the tonsteins in chernogorskaya suite of the Beysk coal deposit (Minusinsk coal basin). Tonsteins of the Beysk deposit are divided into two types: 1. tonsteins of kaolinite (70-100 %) composition, 2. tonsteins of mixed composition. Few kaolinite seams contain P2O5 up to 20 %. Integrated mineral and geochemical analysis allow determining the composition of the initial ash material, which served as a source for formation of tonsteins. Tonsteins formed from felsic volcanogenic pyroclastics are predominant; tonsteins of intermediate volcanic ash are less widespread. Tonsteins formed from mafic and alkaline-base volcanic material are rare. Investigations show that volcanogenic pyroclastics played a significant role in accumulation of rare-earth elements, Zr, hf, Ta, Nb, Y, Th, and U in coals of chernogorskaya suite in the Beysk coal deposit. We also discussed possible sources of ashes that formed the tonsteins.