Geochemistry and zircon geochronology of granitoids in Tavşanlı zone (Eskişehir-Sivrihisar)

In this study, granitoid rocks outcropping in Sivrihisar and Günyüzü (Tekören, Kadıncık, Dinek, Karacaören) regions of the Tavşanlı Zone were investigated. Petrographic, geochemical and U-Pb zircon dating analyzes were performed on the rocks studied, and the composition, properties, which in turn, radiometric age data of those rocks were evaluated. Sivrihisar and Günyüzü granitoids, located within the study area of the Tavşanlı Zone, which extends for approximately 280 km in the east-west direction in Western Anatolia, appear to be characterized in a geodynamic environment associated with arc-like magmatism. In the classification diagrams prepared according to the results of the analysis, it was observed that they are in the composition of Monzonite/Syenite in the Sivrihisar intrusive rocks, Quartz/Monzonite and Granite in the Tekören, Kadıncık, Dinek and Karacaören stocks. It was observed that amphibole, plagioclase and accessory minerals played a crucial role in the formation of the rocks according to the tendencies of the main and trace element enrichments. The rocks in the study area display high SiO2 (51.6%-76.1%) and K (Potassium) contents. Based on the chondrite-normalized diagrams of the samples, light rare-earth elements are more enriched than heavy rare-earth elements. These enrichments can be explained by prior subduced slab contribution to batch melting zone. The U-Pb zircon age data of the rocks obtained from the Sivrihisar and Günyüzü region corresponds to the Middle Eocene-Late Cretaceous period between the era of 42.4 Ma and 78.4 Ma. Enclaves and aplitic dykes were also followed through the main plutonic bodies. These microgranular mafic enclaves likely reach 30 cm in diameter. According to the results of the analysis performed on the samples from the Sivrihisar and Günyüzü (Tekören, Kadıncık, Dinek, Karacaören) stocks, the processes of fractional crystallization, assimilation and magma mixing were main process for forming of the felsic magma.