We investigated the distribution patterns and evaluated the average contents of trace elements in the k₇ seam of the Karaganda coal basin in Central Kazakhstan. This paper presents the results of studying the geochemistry of 34 elements in 85 samples of the k₇ seam. The study employed a suite of advanced high-resolution analytical methods, including atomic emission spectrometry with inductively coupled plasma (ICP–OES) and mass spectrometry with inductively coupled plasma (ICP–MS), along with their processing and interpretation. It was determined that the concentrations of trace elements in the k₇ seam are primarily associated with lithophile elements, revealing high concentrations of Li, V, Sc, Zr, Hf, and Ba. Additionally, increased concentrations of Nb, Ta, Se, Te, Ag, and Th were observed compared to the coal Clarke. Specific Nb(Ta)–Zr(Hf)–Li mineralization accompanied by a group of associated metals (Ba, V, Sc, etc.) was identified. The study revealed lateral and vertical heterogeneity of the rare elements’ distributions in coals, attributed to the formation dynamics of the coal basin. A correlation between Li and Al₂O₃ with a less positive relationship with K₂O suggests the affinity of certain elements (Li, Ta, Nb, and Ba) to kaolinite. Clay layers showed increased radioactivity, with Th—13.2 ppm and U—2.6 ppm, indicating the possible presence of volcanogenic pyroclastic rocks characterized by radioactivity. Taken together, these data reveal the features of the rock composition of the source area, which is considered a mineralization source. According to geochemical data, it was found that the source area mainly consists of igneous felsic rocks, indicating that the formation occurred under conditions of a volcanic arc. This study’s novelty lies in estimating the average trace elements in the k₇ seam, with elevated concentrations of certain elements that suggest promising prospects for industrial extraction from coals and coal wastes. These findings offer insights into considering coal as a potential source of raw material for rare metal production, guiding the industrial processing of key elements within coal. The potential extraction of metals from coal deposits, including from dumps, holds significance for industrial and commercial technologies, as processing critical coal elements can reduce disposal costs and mitigate their environmental impact.

Geochemical specialization of the Shubarkol deposit coals

A comprehensive assessment of the critical elements contained in coal is essential for understanding the geological processes that affect the enrichment of these elements, which can then be used to fully utilize coal in an economically and environmentally friendly manner. In order to understand the geology of an area and the impact of demolition rock on the formation and enrichment of trace elements, as well as rare earth elements (REE) in coals, we have presented a range of recent geochemical and mineralogical data from the k₇ coal seam in the Karaganda Formation of the Karaganda Coal Basin. The study revealed that the geochemical characteristics of coal-bearing deposits in the Karaganda Basin reflect the features of its geological evolution. Despite high tectonic activity and volcanic activity in the Paleozoic era, the specific composition of the rocks on the slopes and bases of coal-bearing valleys has determined the low potential for rare metals in the basin. It has been found that the coal in the Karaganda Basin is, in general, similar in terms of concentrations of most trace elements to the average for world coal. The main area of provenance of the trace elements was established using discriminant diagrams. It was established that the main source of the trace elements, including REEs in the basin coals, was the Tekturmas accretionary complex that represented the main upland (anticlinorium) during the coals’ formation. SEM studies identified micro-mineral forms that indicated the presence of trace elements of Zr, Ti, Se, and Fe in the samples of stratum k₇.

Purpose. Studying geological formations of the Atasu type deposits to identify prospecting criteria. Methodology. Analysis of literature and fund materials, comparative analysis of geological factors characteristic of stratiform ores, stage formation and metamorphism. Findings. The main features characteristic of the deposits of the Atasu type have been formed: their belonging to the lower strata of the Upper Famennian, Upper Devonian to the Visean stage of the Lower Carboniferous; complex composition of ferromanganese and polymetallic ores formed in three hydrothermal stages (sedimentary, metasomatic and vein ones), stratiform, lenticular, localized near volcanic edifices. Originality. The main geological criteria have been established that determine the belonging of the Uspensky ore belt in Central Kazakhstan deposits to the stratiform deposits of the Atasu type formed at different depths in continental rift valleys. The criteria include the age interval of the formation of ore deposits of the stratiform type, hydrothermal staging of mineralization (sedimentary, metamorphic, metamorphic (hydrothermal, dislocation multistage and dynamothermal)); localization of folded and post-folded subvolcanic intrusions near former volcanic edifices. Practical value. The main prospecting geological criteria (features) established for the Atasu type deposits can be used to form a feature space for predicting the areas of mineral deposits localization of the Uspensky ore belt of Central Kazakhstan formed in close time periods, in similar geological-geochemical, thermodynamic and geodynamic conditions.

Purpose. To study the features of the paleotectonic development of the area and to construct paleotectonic reconstruction of the deposit formation to establish the nature of impurity elements accumulation in the coals and enclosing rocks of the Shubarkol deposit, as well as to increase the mineral resource potential of coals. Methodology. 25 samples of coal and mudstone from the Shubarkol deposit were analyzed. The samples were studied by instrumental neutron- activation analysis (INAA) at the Nuclear Geochemical Laboratory of National Research Tomsk Polytechnic University. Findings. An analysis of geological-structural and paleotectonic formation conditions of the Jurassic coal deposit was carried. The factors of formation of coal and carbon-containing rocks enriched with impurity elements and the conditions needed for its leaching and transportation to the coal seam were analyzed. It was found that the coals in individual samples have average concentrations of Ce, Ba, Sr, Sc, Zn that are higher than the clarke, and Sm, Ce, U, Cr, Yb, Ba, Sr, Nd, As, Sc, Zn, Eu, La in the composition of mudstone have average values that are higher than in coals, and higher than the clarke. It was established that one of the sources of rare-metal mineralization of coals (peat) in the Mesozoic and Cenozoic times were the rock massifs of the Kokchetau uplift in the north and northwest, the Kaptyadyr, Arganatinsk and Ulutau mountains in the west. They form the chain of the Kokchetau-North Tien Shan ancient folded structure and the Central Kazakhstan (Devonian) volcanic-plutonic belt in the east. They surround the sedimentation basin and serve as suppliers of clastic material during the coal-bearing strata formation due to tectonic processes of the Mesozoic-Cenozoic time. Originality. The paleotectonic development of the Shubarkol deposit area during the coal-bearing formation has been reconstructed. It has been established that the Sarysu-Teniz uplift in the Permian-Triassic is separated into an independent block, to which the studied deposit is spatially and genetically related. It has been established that the distribution of elements in the coals of the Shubarkol deposit is determined by the peculiarities of metallogeny, geochemistry of the framing area and the mechanisms of the elements entering the coal seams. Practical value. A purposeful analysis of materials for the peculiarities of high concentrations of impurity elements accumulation in coal in connection with deep fault zones at the Shubarkol deposit serves as an objective justification of the possibility of their integrated use, ensuring the development of the countrys coal industry.

The article presents the results of studying the mineralogical and geochemical features of coals and clay interlayers of the Shubarkol deposit. There were analyzed 71 samples of clay layers and 49 samples of coal using the instrumental neutron activation analysis (INAA), powder X-ray diffractometry, and scanning electron microscopy. A comprehensive analysis of the geochemical and mineralogical characteristics of coals and their enclosing clay interlayers was carried out. A variety of geochemical criteria made it possible to establish the facts of the rare earth elements (REE) migration, and the latest data of mineralogy made it possible to establish the ways of their transportation to the paleobasin in the syn- and epigenetic periods of the Shubarkol deposit formation. The data of the paleoclimate and water composition of the paleobasin of peat formation are presented for the first time. Among other things, the analysis made it possible to identify a number of independent sources and various mechanisms of REE accumulation in the sediments of the Shubarkol deposit. The main patterns of the REE distribution that are expressed in the predominance of light lanthanides over heavy lanthanides, were established, and the role and composition of the rocks surrounding coal deposits in the concentration of REE were considered. Aluminosilicates, sulfides, and sulfates with inclusions of microparticles of rare and rare-earth REE elements were found in coals and clay interlayers.