Exploring rare earth elements in Northern Kazakhstan: The potential of ion-adsorption clays and coals as unconventional sources

IF 1.4 4区地球科学 Q3 GEOCHEMISTRY & GEOPHYSICS

Acta Geochimica Pub Date : 2025-10-13 DOI:10.1007/s11631-025-00828-0

Medet Junussov, Maxat K. Kembayev, Manshuk Kokkuzova, Akmaral Baisalova, Zamzagul T. Umarbekova, Rustem Abirov, Sayat Erbolatuly Rais, Abylay Amantayev

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Abstract

This study presents the first integrated mineralogical and geochemical investigation of unconventional rare earth elements (REEs) in ion-adsorption clay (IAC) from the weathered granitic complex of Souktal and coal-derived samples from Saradyr and Bogatyr mines in Kazakhstan. Six representative samples were analyzed using mineralogical, geochemical, and petrographic methods, along with CIA/CIW (chemical index of alteration/weathering), and elemental ratios to assess weathering intensity and provenance. Results show that REEs in IAC samples are primarily adsorbed onto kaolinite and likely apatite under mildly acidic conditions (pH 4.8–5.0), with high CIA/CIW values (> 93.2) indicating advanced weathering. In coal ash, REEs are mainly hosted in organic matter and phosphate minerals, showing a strong correlation with organic carbon, while CIA/CIW values (> 62.8) indicate moderate to high weathering intensity. Provenance analysis indicates felsic sources for IAC and mixed mafic–intermediate for coal-derived samples. Although Coutl values (1.1–1.7) are promising, total REEs concentrations remain below 10 ppm, suggesting subeconomic potential. The findings reveal that all samples from the studied deposits are characterized by high weathering under arid climatic conditions, exhibiting an enrichment pattern similar to underdeveloped global analogs. This reflects a complex interplay between weathering intensity, regolith development, coalification dynamics, sediment source, hydrology, and organic-phosphate host phases in controlling REEs distribution. REEs enrichment in both IAC-type and coal-hosted deposits is influenced by arid-zone supergene processes and coastal plain diagenetic pathways. Future research should target deeper weathered regoliths in IAC systems and surrounding coal seam rocks, using advanced analytical and stratigraphic tools to clarify REEs speciation and the influence of paleoclimate and tectonics on their accumulation in North Kazakhstan.

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在哈萨克斯坦北部勘探稀土元素：离子吸附粘土和煤作为非常规资源的潜力

本文首次对来自哈萨克斯坦Souktal风化花岗岩杂岩和Saradyr和Bogatyr煤矿煤源样品的离子吸附粘土（IAC）中的非常规稀土元素（ree）进行了矿物学和地球化学综合研究。采用矿物学、地球化学和岩石学方法对6个代表性样品进行分析，并结合CIA/CIW（蚀变/风化化学指数）和元素比来评估风化强度和物源。结果表明：在温和酸性条件下（pH 4.8 ~ 5.0），稀土元素主要吸附在高岭石上，也可能吸附在磷灰石上，且CIA/CIW值较高（> 93.2），表明风化作用较强；在煤灰中，稀土元素主要赋存于有机质和磷矿物中，与有机碳具有较强的相关性，而CIA/CIW值（> 62.8）显示出中~高风化强度。物源分析表明，IAC的物源为长英质硅质，煤源样品为镁质-中间物混合。虽然col值（1.1-1.7）很有希望，但总稀土浓度仍低于10ppm，表明具有亚经济潜力。研究结果表明，所有样品均具有干旱气候条件下的高度风化特征，其富集模式与不发达的全球类似物相似。这反映了风化强度、风化层发育、煤化动力学、沉积物来源、水文和有机磷酸盐寄主相在控制稀土分布中的复杂相互作用。iac型和煤型矿床的稀土富集均受干旱区表生作用和海岸平原成岩作用途径的影响。未来的研究应瞄准IAC系统和周围煤层岩石中更深的风化风化层，利用先进的分析和地层学工具来澄清北哈萨克斯坦地区稀土的形态以及古气候和构造对其聚集的影响。

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来源期刊

Acta Geochimica GEOCHEMISTRY & GEOPHYSICS-

CiteScore

2.80

自引率

6.20%

发文量

1134

期刊介绍： Acta Geochimica serves as the international forum for essential research on geochemistry, the science that uses the tools and principles of chemistry to explain the mechanisms behind major geological systems such as the Earth‘s crust, its oceans and the entire Solar System, as well as a number of processes including mantle convection, the formation of planets and the origins of granite and basalt. The journal focuses on, but is not limited to the following aspects: • Cosmochemistry • Mantle Geochemistry • Ore-deposit Geochemistry • Organic Geochemistry • Environmental Geochemistry • Computational Geochemistry • Isotope Geochemistry • NanoGeochemistry All research articles published in this journal have undergone rigorous peer review. In addition to original research articles, Acta Geochimica publishes reviews and short communications, aiming to rapidly disseminate the research results of timely interest, and comprehensive reviews of emerging topics in all the areas of geochemistry.