Rare earth element-bearing fluorite deposits of Turkey: An overview

Rare Earth Element (REE)-bearing fluorite deposits in Turkey occur in association with Cenozoic post-collisional alkaline-carbonatite systems and can be divided into three groups: (1) carbonatite-associated; (2) those associated with subalkaline to alkaline magmatic rocks of Cretaceous to Cenozoic age; and (3) those in sedimentary successions, typically in areas dominated by limestone. Some of these deposits show significant enrichment in the REE, especially the Kızılcaören deposit which has average REE grades of almost 30,000 ppm; others have very low REE contents but have potential fluorite resources. The homogenization temperature and salinity values of fluid inclusions in these deposits vary between 600 °C and 150 °C, and 10–65 wt% NaCl eq., respectively. The carbonatite-associated deposits have the highest bulk REE contents and are LREE-enriched. As a general feature, the REE contents of the fluorite deposits decrease with decreasing homogenization temperatures and salinity of the fluorite fluid inclusions. Fluorite ore chemistry indicates that a plot of Nb + Ta versus total REE differentiates the carbonatite- hosted from the alkali intrusive- hosted and carbonate- hosted deposits. Beyond the cooling and/or dilution of the fluids, REE and fluorite deposition was driven by changes in pH, instead of change in Eh, according to our geostatistical treatment. The chondrite-normalized rare earth element patterns of each group of deposits show some similar features, indicating that the REE in the fluorite are independent of their host lithology, but reflect the magmatic systems from which they were derived. Overall, the F-REE deposits of the Anatolides-Taurides in Turkey are considered to be largely related to the post-collisional magmatic systems, but with variable contributions of fluids from other sources.