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Geology and petrology of Beypazari Granitoids : Yassikaya sector

Billur, Başak
Beypazari Granitoid is a low temperature and shallow-seated batholite intruded the Tepeköy metamorphic rocks of the Central Sakarya Terrane. Composition of the granitoid varies from granite to diorite. The granitoid is unconformably overlain by Palaeocene and Eocene rock units. Thus the age is probably Late Cretaceous. The Beypazari Granitoid comprises mafic microgranular enclaves. The granitoid mainly consists of quartz, plagioclase, orthoclase and minor amphibole, biotite, chlorite, zircon, sphene, apatite, and opaque minerals. Plagioclase shows sericitation whereas biotite and hornblende, chloritization. Holocrystalline and hypidiomorphic are characteristic textures of the granitoid. Geochemically, the Beypazari Granitoid is calc-alkaline, metaluminous and I-type. REE data indicate that it may have been generated from a source similar to the upper continental crust. The trace element data of the Beypazari Granitoid suggest a volcanic arc tectonic setting. The possible mechanism of Beypazari granitoid is the northdipping subduction of Neo-Tethyan northern branch under Sakarya continent during Late Cretaceous. The Beypazari Granitoid may be related with Galatean volcanic arc granitoids.