Biostratigraphy of upper paleozoic-mesozoic radiolaria from Karaburun (İzmir)

In this study, it was aimed to contribute to the geological evolution of the region by conducting detailed paleontological studies in the units containing pre-Neogene, well preserved radiolaria fossils in the Karaburun Peninsula, located in the Bornova Flysch Zone of the Izmir-Ankara Suture Zıne in the western Turkey. It is still contradictive whether the Bornova Flysh Zone is paleogeographically related with the northern or southern margin of the Izmir-Ankara suture zone. Radiolarian assemblages are important to understand relation between Bornova Flysh Zone, which is covering the Karaburun Peninsula, and the Izmir-Ankara Ocean in a paleogeographic perspective. Altough, there are many studies about Mesozoic carbonate platforms in Karaburun Peninsula, Mesozoic and Upper Paleozoic aged radiolarian cherts has been poorly surveyed. In this study, four measured sections with well preserved radiolarian assemblages were recovered in Karaburun Peninsula within Bornova Flysh Zone, which is related with Izmir-Ankara Suture Zone in western Turkey; Ildır measured section, Karareis measured section, Kalecik measured section and Gerence measured section. Ildır measured section which is represented by coarse to fine grained, greenish brown sandstone, claystone and black chert alternation thinly bedded with 10 meters total thickness, is located in west of the Karaburun Peninsula, in the Ildır village. Karareis measured section within 30 centimeters thick layer black cherts is located Gerence bay, western Karaburun peninsula. Both Ildır and Karareis measutred sections identified as Dikendağı formation by Çakmakoğlu and Bilgin (2006) and contain Upper Paleozoic (Devonian) aged based on radiolarian assemblages as Bisphaera solidispinosa Won 1997a, Trilonche minax Hinde 1899, Inaequalientactinia typica Won, 1991, Ornatoentactinia beljaevorum Afanasieva 2000a, Trilonche davidi (Hinde 1899), Bientactinosphaera symphypora Foreman, Moskovistella mira Afanasieva 1997b. Kalecik measured section within Bornova melange (Erdoğan, 1990), which is located in northern part of the Karaburun Peninsula and near the Kalecik town, is represented by red bedded cherts as a block with thickness of approximately 15 meters and contains Upper Bathonian-Tithonian aged (UAZ 7-11) radiolaria species including Transhsuum brevicostatum gr. (Ozvoldova), Tritraps exotica (Pessagno), Angulobracchia biordinalis, Tritraps cf. casmaliaensis (Pessagno), Emiluvia bisellea n.sp. Danelian, Acanthocircus subobloyngus minor n.ssp. Baumgartner. Bornova melange consist of olistostromal levels including limestone clasts and blocks with a sandstone mudstone dominated matrix, and radiolarites and generally altered basic volcanic rocks, ultrabasic rocks and limestone blocks of various age (Çakmakoğlu and Bilgin, 2006). Lastly Gerence measured section is located just southeast of the Ildır village, west of the Karaburun Peninsula, and is represented by discontinuous red bedded cherts with thickness of approximately 35 meters, containing middle Triassic aged radiolaria genus and species as Triassospongosphaera multispinosa (Kozur et Mostler, 1979), Triassospongosphaera erici Feng n. sp , Eptingium manfredi Dumitrica, Eptingium nakasekoi Kozur et Mostler, 1994, Astrocentrus pulcher Kozur ve Mostler 1979a. The middle Triassic to late Jurassic and Devonian ages obtained from these well-dated sections indicate the presence of pelagic sedimentary environments developed in two different periods on the Karaburun Peninsula.