REE AND THORIUM MINERALOGY IN FLUORITE DEPOSITS IN KULUNCAK-MALATYA, TURKEY

In this study, we examined the occurrence of rare earth elements (REEs) in fluorite deposits in Kuluncak-Malatya, Turkey. A literature has reported thorium-rich britholite veinlets in carbonatite bodies with fluorite and apatite in Kuluncak area. This area is located in the Anatolide-Tauride terrane and used to be a back arc basin before the closure of the ancient ocean related with the Assyrian suture zone. Alkaline magmatism is observed in the area to form one of the biggest iron deposits in Turkey and other base metal deposits. The carbonate-hosted fluorite deposits were found in Kuluncak at the contact of Cretaceous limestone and Eocene syenitic rock. In the contact zone, anomalous radioactivity was observed, especially in the fluorite ore. Fluorite- and phlogopite-rich carbonate samples showed anomalous contents of thorium and REEs, especially of lanthanum and cerium. Thorium and REE contents in the samples were in the ranges of 0.00-0.25% ThO₂ and 0.03-1.46% REO, respectively, other than the maximum of 2.48% ThO₂ and 1.78% REO. Unlike the Cretaceous limestone, the syenitic rock was 2-3 times more enriched with light REEs (LREEs) and thorium compared to the average of the lithosphere. The intrusion of syenitic rock should thus be responsible for the enrichment of REEs and thorium in carbonate-hosted fluorite deposits. We observed various minerals with significant contents of REEs, thorium, uranium, and niobium. The most common REE minerals were REE fluorocarbonates, such as parisite and synchisite. We also observed some REE preferentially incorporated into a specific type of mineral.