This study focuses a comprehensive mineralogical and geochemical study of rare-metal (Zr-Nb-Hf-Ta-REE-Ga) mineralization in the Permian coal seam XXX-XXXa of the Izykh Coalfield, Minusinsk Basin, southern Siberia. A link is demonstrated between the accumulation of rare metals in the coal with a volcanogenic rock parting up to 45 cm thick separating the coal seams. The floor of seam XXX is also characterized by the presence of pyroclastic material, which affects the level of accumulation of rare elements in the coal of the seam. Coals and intra-seam rock partings in seam XXX-XXXa have abnormally high concentrations of Zr, Nb, Hf, Ta, REE and Ga. In coal ash samples, the contents of some elements are highly evaluated, e.g., 1.4% Zr, 0.26% Nb, 164 ppm Hf, 17.9 ppm Ta, 0.8% REE, 0.13% Y, and 226 ppm Ga. The concentration of rare elements is higher in the coal and coal ash of the XXX coal seam than in the XXXa coal seam. The accumulation of anomalous concentrations of Zr-Nb-Hf-Ta-REE and Ga is mostly specific for the rock parting between the XXX and XXXa seams, as well as for the coals in contact with this parting. Zirconium, Nb, Y, and REE form more contrasting halos near the parting compared to Ta, Hf, and Ga. This is explained by the different mobility of the elements under weathering and diagenetic conditions. Other ore elements are concentrated to a greater extent in the coal in the near-contact zone, as well as at a distance from the partings. Ore material is concentrated primarily in the fine-dispersed mineral phase represented mainly by Zr-Nb-Ti-Fe oxides, complex Nb-Zr-P silicates, and REY-bearing phosphates (monazite, xenotime). Volcanogenic pyroclastics of acidic and alkaline composition (rhyolite-pantellerite) influenced the accumulation of rare metals in coal. Volcanic ash, transported from a distant source, served as the raw material for the formation of the rock interlayer in coal. The composition of this volcanic ash is believed to correspond to a pantelleritic tuff. These findings are comparable to those reached in earlier work on the altered ash in the coal seam XI of the Kuznetsk Coal Basin, which has similar geochemical features and is also of Permian age. Complex Zr-Nb-Hf-Ta-REE-Ga mineralization in the coals of the Kuznetsk and Minusinsk basins, associated with volcanogenic pyroclastics, indicates a wide manifestation of active acid and alkaline volcanism during the formation of coal deposits and the possibility of identifying similar mineralization in Permian coals of East and North Asia.

中文翻译：

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俄罗斯米努辛斯克盆地伊济赫煤田 XXX 煤层稀有金属 (Zr-Nb-Hf-Ta-REE-Ga) 煤的矿物学和地球化学：对北亚更广泛的稀有金属矿化的影响


本研究重点对西伯利亚南部米努辛斯克盆地伊济赫煤田的二叠纪煤层 XXX-XXXa 中的稀有金属 (Zr-Nb-Hf-Ta-REE-Ga) 矿化进行全面的矿物学和地球化学研究。煤中稀有金属的积累与分隔煤层的厚达 45 厘米的火山岩之间存在联系。 XXX煤层底板的另一个特点是存在火山碎屑物质，影响煤层煤中稀有元素的富集水平。 XXX-XXXa煤层煤及层内岩缝中Zr、Nb、Hf、Ta、REE、Ga含量异常高。粉煤灰样品中某些元素含量评价较高，如Zr 1.4%、Zr 0.26%。 % Nb、164 ppm Hf、17.9 ppm Ta、0.8% REE、0.13% Y、226 ppm Ga。XXX煤层的煤和煤灰中稀有元素的浓度高于XXXa煤层。 Zr-Nb-Hf-Ta-REE 和 Ga 异常浓度的积累主要针对 XXX 和 XXXa 煤层之间的岩石分界以及与该分界接触的煤。与 Ta、Hf 和 Ga 相比，锆、Nb、Y 和 REE 在分界附近形成更具对比性的光晕。这是由于元素在风化和成岩条件下的不同迁移率来解释的。其他矿石元素更大程度地集中在近接触区以及距分理处一定距离的煤中。矿石材料主要集中在细分散矿物相中，主要由 Zr-Nb-Ti-Fe 氧化物、复合 Nb-Zr-P 硅酸盐和含 REY 的磷酸盐（独居石、磷钇矿）代表。酸性和碱性成分的火山碎屑岩（流纹岩-潘氏沸石）影响煤中稀有金属的积累。 从遥远的地方运来的火山灰是形成煤中岩石夹层的原材料。据信这种火山灰的成分相当于潘氏凝灰岩。这些发现与早期对库兹涅茨克煤盆地 XI 煤层蚀变灰分的研究结果相当，后者具有相似的地球化学特征，也属于二叠纪时代。库兹涅茨克盆地和米努辛斯克盆地煤中复杂的 Zr-Nb-Hf-Ta-REE-Ga 矿化与火山碎屑岩相关，表明在煤矿床形成过程中存在广泛的活性酸性和碱性火山活动，并有可能识别类似的矿床。东亚和北亚二叠纪煤炭的矿化。