We investigate rare earth element geochemistry, microthermometric characteristics, and radiogenic isotope systematics of fluorites and stable isotope compositions of gangue minerals from several fluorite deposits in central Turkey. In the deposits, fluorite is the main ore mineral and it is accompanied by quartz, calcite, and minor pyrite and barite. Veins are represented by three different fluorite types based on their color. Total REY contents of fluorites are highly variable, ranging from 24 to 693 ppm. LREE concentrations of fluorites of all colors are similar but medium and heavy REE abundances of green fluorites are nearly an order of magnitude greater than in both host rocks and purple and yellow fluorites, indicating multiple sources for crystallization. REEs show significant fractionation and purple fluorites with relatively low HREE contents were likely precipitated at an earlier stage. As crystallization continued, green fluorites were nucleated because of ion exchange of LREEs with the host rock/minerals. Fluid inclusions yielded a wide range of homogenization temperatures from 86 °C to 292 °C and salinities from 0 to 20 wt.% NaCl equiv. The 87 Sr/ 86 Sr ratios of fluorites, varying from 0.707627 to 0.709380, overlap with the range of host rocks. 143 Nd/ 144 Nd values suggest two populations: purple fluorites with less radiogenic and green fluorites with more radiogenic Nd isotope ratios. The Sr-Nd isotope systematics of Bayındır fluorites are consistent with that of the Bayındır syenite, indicating that hydrothermal solutions progressively reacted with the host rock until equilibrium was established. δ 18 O values of quartz are slightly higher than the magmatic range. δ 13 C and δ 18 O of calcites fall into the range of marine carbonates. δ 34 S values of barites indicate derivation from diverse reservoirs changing from marine to terrestrial sources. In contrast, sulfur in pyrites points to a magmatic origin. Therefore, is it suggested that magmatic fluids to some extent contributed to the precipitation of fluorite veins.

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In this study uranium and thorium contents and depositional characteristics of Çayirhan bituminous shales (ÇBS), west of Ankara (central Anatolia), are investigated. Samples used were collected from boreholes opened by Park Holding Ltd. A total of 25 samples were taken from bituminous shale levels in boreholes drilled at 6 different locations in the study area. The Hirka formation which hosts bituminous shale deposits is a volcano sedimentary sequence and all lithofacies indicate that a lacustrine environment where the water level was continuously changed. In addition to hydrocarbon generation potential, bituminous shales also accumulate significant amount of radioactive elements such as uranium and thorium. The average uranium and thorium concentrations of ÇBS (1.83/2.62 ppm) are much lower than averages of UC, NASK and PAAS (uranium: 2.70/2.66/3.10 ppm; thorium: 8.50/12.30/14.60 ppm). Low uranium contents in comparison to those of similar lacustrine environments might be attributed to that waters of depositional environment of ÇBS contain low concentration of dissolved uranium and redox conditions were of oxic and dioxic character. Correlation data indicate that U and Th have a similar source and are associated predominantly with clays and phosphates and dominantly with organic material. Radioactive elements in the basin might be derived from Paleozoic granites and metamorphites (e.g. gneiss, schist) which comprise the basement and volcanism which was active in the region throughout the Miocene period. These elements are probably associated with uraniferous phosphate minerals (e.g. autunite, torbernite) which occur in granite, gneiss and schist. ÇBS with average TOC content of 10.96 % shows very good/perfect source rock potential. Positive correlations between Gamma‐Ray values and U, Th and K concentrations imply that radioactivity might be originated from these three elements.