Turkish Journal of Earth Sciences




The Biga Peninsula in northwestern Anatolia is a tectonic mosaic, comprising different tectonic units, representing the Sakarya Continent and oceanic assemblages of different origin and ages. The Çamlıca metamorphic association, a member of this orogenic mosaic in the westernmost part of the peninsula, is subdivided into three formations, from bottom to top; the Andıktaşı formation, the Dedetepe formation, and the Salihler formation. Eclogite-facies metamorphic rocks occur as tectonic slices within schist-marble intercalations of the Dedetepe formation. These slices, about 2 km long and 500 m wide, include two different rock types; (i) quartz-mica schists, and (ii) metabasite lenses with eclogite/blueschist paragenesis. Foliation in the Dedetepe formation of the Çamlıca metamorphic association generally dips SW and strikes NW-SE around Dedetepe hill and Çamlıca village. In contrast, eclogite-facies metabasite slices strike NE-SW with NW-dipping foliation. The eclogite-facies metabasite lenses are typically low-temperature eclogites that may represent tectonic slices of an accretionary complex associated with a subduction zone. Blueschists were produced by retrograde metamorphism from eclogite during late stage shearing. The host rocks record only a single-stage greenschist-facies metamorphism and were juxtaposed with the eclogite-facies metamorphic rocks along ductile-semi-brittle (?) strike-slip faults after the eclogite-facies metamorphism and during or after the low-grade metamorphism of the Çamlıca metamorphic unit. Age constraints on the metamorphic units and the age of the common cover units suggest that this juxtaposition by strike-slip tectonics occurred between the late Cretaceous and early Eocene.

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