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

Geology and genesis of the Silica-Listwaenite hosted Kaymaz gold deposit, Eskişehir, NW-Turkey: Implications from fluid inclusions and pyrite chemistry

The Kaymaz gold deposit comprises Damdamca, Karakaya, Küçük Mermerlik, and Kızılağıl ore zones within an area underlain by serpentinite and far-traveled Paleozoic-Mesozoic high-pressure metamorphic rocks. The Kızılağıl ore zone is hosted in silicified quartz schist, whereas the others are hosted in silica altered serpentinite. Pyrite-I, arsenopyrite, marcasite, magnetite, pentlandite, millerite, nickeline, bravoite, and fine-grained native gold and silver comprise the first stage, whereas pyrite-II and chalcopyrite represent the second ore stage. The Kaymaz gold deposit has been defined as a silica-listwaenite hosted gold deposit according to host rock relations and mineralogical properties. Gold, Ag, and As were found to be highly correlative in whole-rock silica-listwaenite analyses. Higher As content of the pyrite-I, coexisting native gold and silver together with the whole-rock analyses indicate that these metals were derived from the same source, possibly the Kaymaz granite. On the other hand, clathrate formations observed in some of the first stage fluid inclusions confirm that high Ni in the pyrite-I may have been derived from the serpentinites. However, a distinct lack of the separated carbonic phase and clathrate formations in the second stage fluid inclusions as well as their lower Th and salinities, reveal that higher Co in the pyrite-II possibly dissolved from the metabasites by meteoric solutions

Geochemical characteristics of iron ore deposits in central eastern Turkey: an approach to their genesis

<p>Economically the most important iron deposits of Turkey occur as: (1) skarn-hosted (SH)-type ore deposits, occurring along the contacts between syenitic-monzonitic intrusives and limestone or serpentine; (2) vein-type deposits, found between the serpentine and limestone (SLH); or (3) ore deposits that are entirely within the limestone (LH).</p> <p>Elemental associations are defined as: Fe+Ni+Cr+U+Bi+Rb+Mg+Ga for the SH-type ores; Fe+Cr+Mn+Nb+V for the SLH-type ores; and Fe+Ag+Au+Cr+Ba+As+Pb+Sb+Ni for the LH-type ores. Positive correlations between Fe, U, Bi, and Rb for the SH type indicate that late magmatic hydrothermal input was related to monzonitic intrusions. Chondrite-normalized rare earth element (REE) patterns of the 14 deposits show very weak light/heavy REE (LREE/HREE) fractionation. Similarities of REE patterns, particularly between the SH and LH types, may indicate a common source of REEs and Fe. Ce depletion in the LH ores indicates long-term fluid flow and interaction with marine sediments. Ni, Cr, and V enrichment of all deposits indicates that iron was scavenged from the serpentinized ultra-basic-basic rocks and transported along fracture zones by hydrothermal solutions driven by intrusions. The iron deposits were formed around the magmatic bodies, or tectonic contacts between the serpentine and the limestone.</p