Gürsel SUNAL, Thomas ZACK, ARAL I. OKAY, Mehmet Korhan ERTURAÇ, Gültekin TOPUZ

The Early Eocene Ekmekçi granodiorite porphyry in the Karacabey region (Sakarya Zone, NW Turkey)

The Ekmekçi granodiorite porphyry is a unit in the E-W trending, postcollisional Eocene magmatic rocks of northernAnatolia. It occurs as a relatively small stock, but represents a link between plutonic and volcanic rocks. This Early Eocene granodioriteporphyry intruded into the Upper Triassic rocks of the Karakaya complex in the Sakarya Zone. In this study we present geochemicaland zircon U-Pb LA-ICP-MS age data to contribute to understanding the Early Tertiary postcollisional tectonic setting of NW Anatolia.The granodiorite porphyry includes plagioclase, quartz, hornblende, K-feldspar, biotite, and minor zircon, apatite, sphene, and opaqueminerals. The stock displays medium-K calc-alkaline I-type and metaluminous affinity. Similar to other Eocene magmatic rocks, itdisplays characteristic features of subduction-related magmatism, such as enrichment in large-ion lithophile elements relative to highfield strength elements and enrichment of light rare earth elements relative to heavy rare earth elements with a lack of significant Euanomalies. They are characterized by homogeneous initial Sr and Nd isotopic compositions of 0.7044–0.7049 and 0.51255–0.51260,respectively. Zircon U-Pb data indicate that the Ekmekçi granodiorite porphyry was emplaced at 5.1 ± 1 Ma (2s Ypresian). Geochemically,the Ekmekçi granodiorite porphyry is similar to mafic volcanic rocks rather than the plutonic rocks of the same age. It was emplaced tothe north of the İzmir-Ankara-Erzincan Suture (northern plutonic belt of NW Anatolia) and can be correlated with southern plutonssuch as Orhaneli, Topuk, Tepeldağ, Gürgenyayla, and Sivrihisar in the Anatolide-Tauride block in terms of age.

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