MINERALOGY AND GEOCHEMISTRY OF TONSTEINS IN COALS OF CHERNOGORSKOE DEPOSIT OF THE MINUSINSK BASIN

Abstract

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 of the research is to study the mineralogical and geochemical features of tonsteins and enclosing coals of сhernogorskaya suite in the Chernogorskoe coal deposit (Minusinsk coal basin). Objects of the research are tonsteins and enclosing coals of сhernogorskaya suite in the Chernogorskoe coal deposit (Minusinsk coal basin). Methods: sampling of coal seams of сhernogorskaya suite in the Chernogorskoe 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, scanning electron microscopy, x-ray diffractometry. Results. The paper studies mineralogical and geochemical characteristics of the tonsteins in chernogorskaya suite of the Chernogorskoe coal deposit (Minusinsk coal basin). Kaolinite is predominant in the composition of the studied tonsteins. Quartz, feldspar, and phosphates are found in smaller amounts. 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 felsic alkali-type volcanic genesis are less widespread. Tonsteins formed from intermediate and mafic volcanic material are rare. On the basis of the identified tonsteins, the sequence of changes in the composition of the pyroclastic material received during peat accumulation was restored. The study found that the pyroclastic material had a significant impact on accumulation of a group of lithophilic rare metals, including abnormally high concentrations of REE, Zr, Hf, Nb, Y, and Th.

Keywords

• coal
• tonstein
• geochemistry
• volcanogenic pyroclastics
• minusinsk basin