Yazarlar
- Çimen, Okay(2)
- Dönmez, Cahit(1)
Yayınlar
- MakaleAçık Erişim2026Geological Formation Environments of Rare Earth Elements: Examples from Around the World and Turkiye
Çimen, Okay; Dönmez, Cahit
Rare earth elements (REEs) are critical raw materials used in strategic fields such as defense, energy, electronics, lasers, and sensor technologies, and particularly in the production of permanent magnets including NdFeB and SmCo types. Since the early 2000s, the global supply of rare earth elements has become dominated by China for mining, beneficiation, and separation processes, as non-Chinese producers have lost competitiveness due to high capital requirements and the costs imposed by environmental regulations. This review addresses the geological formation environments, deposit types, and global reserve-resource distributions of REEs within an integrated framework. REE mineralization occurs within primary geological sources such as carbonatites, alkaline magmatic systems, and iron oxide copper-gold (IOCG) deposits, as well as in secondary sources including ion-adsorption clays, placers, and lateritic formations. Primary sources are generally enriched in light REEs and are characterized by high-cost production processes, whereas heavy REEs are predominantly obtained from secondary sources. Globally, REE reserves are estimated to be approximately 90-120 Mt, while potential resources are on the order of similar to 480 Mt, with China occupying a leading position in terms of both reserves and resources. In Europe, Greenland, Sweden, Finland, Norway, Germany, and Turkiye are among the regions with significant REE potential. In Turkiye, the principal REE areas defined at the deposit scale are the Eski & scedil;ehir-K & imath;z & imath;lcaoren (Beylikova) and Malatya-Kuluncak districts. These districts are associated with alkaline magmatism and display enrichment particularly in Nd and Pr (beyond La and Ce), rendering them strategically important for NdFeB permanent magnet production. Recent studies conducted by Eti Maden indicate that the Eski & scedil;ehir-K & imath;z & imath;lcaoren area hosts a large-scale resource of approximately 694 Mt with total REE grades of1.5-1.8%. The Eski & scedil;ehir-K & imath;z & imath;lcaoren area is related to the extensional tectonic regime of Western Anatolia, whereas the Malatya-Kuluncak area is associated with post-collisional alkaline magmatism of Late Cretaceous-Early Paleocene age developed within the Central Anatolian Crystalline Complex. The presence of similar alkaline systems across Turkiye indicates significant potential for REE exploration and critical mineral strategies. This synthesis provides a comprehensive geological reference framework for the development of REE exploration strategies, the diversification of global supply chains, and evaluation of Turkiyes'REE potential.
- MakaleAçık Erişim2026Scopus SJRQ4Petrography, geochemistry and formation of the Sarıçimen (Van, eastern Türkiye) Fe-Ni-Co laterite deposit
Çimen, Okay
The Sarıçimen Fe-Ni laterite deposit is located in eastern Türkiye (Van province) and represents one of the important Ni and Co-enriched lateritic mineralizations formed in the ophiolitic occurences. This study aims to decipher the petrographic and geochemical signatures of the laterite horizon in order to better figure out the processes controlling Fe-Ni-Co mineralization and the genesis of the deposit. In this study, field and petrographic observations, and whole-rock geochemical data have been used to characterize the mineralogical and geochemical evolution of the lateritic horizon. Petrographic studies indicate that the protolith of the laterite zone is mostly composed of serpentinized ultramafic rocks including relics of Cr-spinel and chromite grains. This lateritic zone is characterized by hematite-and magnetite-rich zones formed above saprolitic levels that may have been derived from the weathering of ultramafic parent rocks. Whole rock geochemical analyses indicate that Fe₂O₃ and SiO₂ are the dominant oxides, and Ni concentrations vary between 0.33 and 1.01 wt.%. Also, Co values are ranging between 330 ppm and 600 ppm in the laterite samples investigated here. More importantly, correlation analyses exhibit a positive relationship between Ni and Fe₂O₃ and this may be attributed to a close association with Fe-oxide minerals during the lateritization. In contrast, a negative correlation between Ni and SiO₂ may indicate the presence of silica depletion during chemical weathering. The geochemical trends investigated here reveal that the laterite zone developed through intense lateritic weathering of ultramafic rocks, which is characterized by the removal of relatively mobile elements such as Si and Ca and the residual enrichment of Fe, Ni, and Co. The presence of Cr-spinel relics once again confirms the ultramafic origin of the parental rocks. Overall, the Sarıçimen deposit represents a Fe-Ni-Co laterite derived from nearby ultramafic sources within the ophiolitic sequence. The occurrence of Fe-Ni-Co laterite deposits at both the southwestern and northeastern segments of the Southern Neotethys Suture Zone suggests that this tectonic belt may represent a promising metallogenic area for lateritic Fe-Ni-Co mineralization in the southern Türkiye.
