The arkosic sandstones with olistostromes within the "Karakaya Complex" in NW Anatolia to the south of Geyve include a thin layer of green chert with radiolaria. Based on the composition of Albaillellids, the radiolarian assemblage corresponds to the Neoalbaillella ornithoformis assemblage, and its age is assigned to the Changxingian (Late Permian). This is the first finding of synsedimentary radiolarian cherts within the Karakaya units and the indication of latest Permian rifting of the Karakaya basin within the Midian carbonate platform and its pre-Permian basement in the Sakarya Composite Terrane.
GÖNCÜOĞLU, M. CEMAL; KUWAHARA, KIYOKO; TEKİN, U. KAĞAN; and TURHAN, NECATİ (2004) "Upper Permian (Changxingian) Radiolarian Cherts within the Clastic Successions of the "Karakaya Complex" in NW Anatolia," Turkish Journal of Earth Sciences: Vol. 13: No. 2, Article 6. Available at: https://journals.tubitak.gov.tr/earth/vol13/iss2/6