Turkish Journal of Earth Sciences

Abstract: The İğdiş Dağı Igneous Complex (IIC) is one of the late-stage plutonic bodies within the Central Anatolian Crystalline Complex (CACC) which intrudes the Paleozoic-Mesozoic metamorphic basement and late Crateceous granitoids. Uppermost Crateceous (?)-Lower Paleocene olistostromal volcaniclastik rocks represent the oldest cover on the IIC. Petrographic and gechemical data indicate that the IIc mainly comprises quartz synite with well-defined alkaline and peralkaline over saturated trends. The analysed samples show humped patterns on chondrite- and ORG-normalized spidergrams with peaks at Rb, Th and Ce, and also negative Nb anomalies. These features are similar to patterns considered typical of post collisional A₂-type granitoids produced by crustal anatexis. A post-collision setting is also suggested by the distribution of data over different fields in chemically-basedtectonic discrimination diagrams employing Nb, Y and Rb. These characteristics are consistent with gechemical data from other CACC granitoids and the regional geology. The late-orogenic plutonic rocks of the CACC (granites and syenites) represent the melt products of continental crust during post-collisional uplift. This event followed crustalthickening that was related to the southward emplacement of ophiolitic nappes during the closure of the İzmir-Ankara-Erzincan Ocean.