Geochemical Features of Miocene Carbonatite/Carbothermalite-Fenite Complex in Western Anatolia: Evidences from Arıklı and Nusratlı Villages

Carbonatite-fenite complexes, associated with alkaline or ultra-alkaline magmatism, typically have high concentrations of rare earth elements (REE), niobium (Nb), thorium (Th) and uranium (U). Although most of these complexes form in intra-continental tectonic settings, in contrast to the majority, they can also develop in post-collisional settings. A few examples of such carbonatite intrusions were identified in China, Turkey, Italy and Spain. In Turkey, a few notable carbonatitic intrusions were identified in Central and Western Anatolia. These complexes are relatively young and some of them are covered by volcanic or volcano-sedimentary rocks. The recently identified carbonatite/carbothermalite (late stage metasomatic halo) intrusion is located at Arıklı and Nusratlı Villages in Çanakkale, NW Anatolia within Miocene volcanics. In Arıklı, a 10-meters-thick carbonatite dyke with stockwork veinlets and potassic fenite zone are clearly visible and cross-cutting relationships can be observed between the carbonatite and the host rocks. Two kilometers east of Arıklı, at the entrance of Nusratlı village, also a metasomatic aureole zone can be observed that consists of thin carbonatite veinlets. These veinlets predominantly constituted by  subhedral calcite, dolomite, and magnesite, forming a Mg-carbonatite composition and they contain small amounts of uranium (~4 ppm) and thorium (<1 ppm). However, the concentrations of these elements increase significantly in the adjacent fenite zone, reaching up to 372 ppm for U and 109 ppm for Th.  An approximately 7% increase in K₂O within the fenite zone has been calculated based on a comparison of the current and original composition of the host rock, using immobile elements as a reference. Overall, this carbonatite/carbothermalite system can be evaluated as late-stage phase of a carbonatitic intrusion which is product of Miocene post collisional magmatism in Western Anatolia.