Rare Earth Element Potentials of Red-Colored Eocene Kazmaca and Upper Eocene-Lower Miocene Incik and Bayindir Formations (Kirikkale, Türkiye)

The red-colored sedimentary rocks of the Kazmaca, Incik, and Bayindir formations, particularly the red mudstones, exhibit noteworthy enrichment in Rare Earth Elements (REEs) and uranium. These fine-grained units were deposited in low-energy lacustrine to shallow-marine environments, where redox-sensitive geochemical processes played a central role in elemental mobilization and accumulation. Mineralogical and geochemical analyses, including XRD, XRF, and ICP-MS, identified the uranium-bearing mineral Fourmarierite, confirming the presence of uranium mineralization. This finding is supported by elevated Cu/Al ratios, increased Fe concentrations, and trace-element distributions indicative of a redox-controlled diagenetic environment. The high Fe concentrations and Cu/Al ratios act as geochemical proxies for REE-hosting phases. The depositional setting, characterized by low dissolved oxygen levels, likely reflects a warm and humid paleoclimate that enhanced chemical weathering and facilitated the mobilization and subsequent precipitation of uranium and REEs. Notably, dark-colored mudstone interbeds within the sandstone sequences exhibit localized uranium accumulation, which may represent precursor zones for secondary REE mineralization. These findings underscore the importance of redox conditions and climatic factors in controlling REE and uranium enrichment in red bed sequences. The presence of Fourmarierite, in conjunction with distinctive geochemical signatures, suggests a significant potential for REE exploration in these formations.