## 1 Introduction
However, comprehensive geochemical investigations of other coal deposits in central and northeast Kazakhstan remain limited. The coal deposits in this region are primarily found in Carboniferous coal basins, which include the largest in Kazakhstan: the Karagandy, Tenyz-Korzhinkol, and Ekibastuz basins, covering a combined area of 4155 km\({}^{2}\) and containing the region's largest coal reserves, totaling 54.4 billion tons [20; 21]. The Carboniferous coals within these basins exhibit a wide range of total coal seams, varying from 6 to 80, with seam thicknesses ranging from 1.5 to 100 m. The Karagandy basin supports approximately 10 underground coal mines, including the active Lenin mine. In the southwest, the Ekibastuz basin produces coal from the Bogatyr mine, while the eastern Tenyz-Korzhinkol basin produces coal from the Saradyr mine [20; 21; 22]. Additionally, the Jurassic coals of this region, found in the Shubarkol and Maikuben coal basins (named after the mines), cover around 1470 km\({}^{2}\) and hold approximately 7.5 billion tons of coal reserves [21; 22; 23]. The Shubarkol mine contains two coal measures (Upper and Lower), with thicknesses ranging from 55 to 70 m. Meanwhile, the Maikuben mine within the Shoptykol formation includes three coal measures (I, II, and III), with a total thickness of approximately 260 to 290 m [21; 22; 23]. The Carboniferous coals are predominantly classified as hard coals, distinguished by high ash content, relatively low volatile matter, and variable sulfur levels, and they frequently exhibit coking properties [21; 22; 23]. In contrast, Jurassic coals are characterized as brown coals and exhibit a lower ash yield and higher volatile matter. Petrographically, the coals from both Carboniferous and Jurassic periods show distinct variations, primarily consisting of vitrinite, liptinite (mainly sporinite), and interinite. The thermal maturity of these coals, as evidenced by vitrinite reflectance measurements, rangesfrom approximately 0.5% to 1.3% across the five coal mines, with potential variations observed across different zones, as discussed by various authors [21; 22; 23]. Coals from these mines are utilized for power and heat generation, as well as steel manufacturing. These five coal mines are the primary focus of this study, aimed at a preliminary inorganic elemental assessment of coal, and will serve as the coal mines for more detailed investigations. This study presents the first report on the inorganic elemental composition of coal ash from five different coal deposits in Kazakhstan, dating to the Jurassic and Carboniferous periods. Although the results are preliminary and based on limited inorganic chemical analysis, they offer new insights into the distribution and modes of occurrence of major and trace elements. These insights could have potential industrial and environmental implications for the coals from these Jurassic and Carboniferous coal deposits. The aims of the present study are as follows: (a) to determine the elemental content of coal ashes from Jurassic and Carboniferous coals sampled at five coal mines; (b) to compare the major and trace element concentrations in coal ash from the five coal mines with the Clarke values of the Earth's crust and global coal ash, aiming to determine the enrichment or depletion of elements and evaluate their potential as a secondary source for recovering valuable elements; and (c) to determine the mode of occurrence and origin of elements for their industrial and environmental implications.