MINERALOGY, GEOCHEMISTRY AND GENESIS OF RARE METAL ZR-NB-HF-TA-REE-GA MINERALIZATION OF THE SEAM XXX OF MINUSINSK BASIN

The relevance of the research is caused by the demand for assessment of volcanic pyroclastic material influence on formation of rare elements geochemical background in coal. The main aim of the research is to identify mineral and geochemical characteristics of coals and surrounding rocks in the seam XXX of Minusinsk coal basin. Objects: coals and surrounding rocks in the seam XXX of Minusinsk coal basin. Methods: sampling of the seam XXX of Minusinsk coal basin; chemical composition is identified with inductively coupled plasma mass-spectrometry (ICP-MS), inductively coupled plasma atomic emission spectrometry (ICP-AES), instrumental neutron activation analysis (INAA): mineral composition is investigated with optical microscopy, petrographic methods, scanning electron microscopy, X-ray diffractometry. Results. The detailed mineral and geochemical investigations of rare-metal Zr-Nb-Hf-Ta-REE-Ga mineralization in the seam XXX-XXXa, Izykh coal deposit, Minusinsk basin were carried out. In coal ash maximum content of Zr is 1,4 %, Nb – 0,26 %, Hf – 164 ppm, Ta – 21,2 ppm, ∑REE – 0,8 %, Ga – 226 ppm. The ore matter is predominantly concentrated in the fine mineral phases, composed mainly of Zr-Nb-Ti-Fe oxides, complex Nb-Zr-P silicates, rare-earth phosphates (monazite, xenotime). The connection between the anomalous concentrations of rare metals and the intraformational seam was established. The main mineral in the intraformational seam is kaolinite (68,9 %), quartz (11,0 %), K-feldspars (7,0 %), and albite (5,6 %) occur less often. This seam has volcanogenic pyroclastics genesis, and its composition is pantellerite-comendite. The intraformational seam enriched with similar rare-metal mineralization was found earlier in coals of Kemerovskaya suite (Kuznetsk coal basin). Complex Zr-Nb-Hf-Ta-REE-Ga mineralization associated with the volcanogenic pyroclastics in coals of both Kuznetsk and Minusinsk basins is an evidence of possible global felsic and alkaline volcanic activity during coal formation and expands the prospects of revealing further such mineralization in Permian coals of other basins.