Wenlock (Silurian) graptolitic shales from the Kocaeli Peninsula (Derince–Izmit), NWTurkey
Authors
Valeri Sachanski
Bulgarian Academy of Sciences, Geological Institute, Acad. G. Bonchev St. Bl. 24, 1113 Sofia
M. Cemal Göncüoglu
Middle East Technical University, Department of Geological Engineering, 06531 Ankara
Ibrahim Gedik
General Directorate of Mineral Research and Exploration, Department of Geological Research, 06520 Ankara
Keywords:
Wenlock, Graptolites, Dark shale, Izmit, Zonguldak Terrane, NW Turkey
Abstract
Alternating dark grey to black thin-bedded limestones and yellowish-grey calcareous shales in a recently discovered section in Izmit (Derince), eastern Kocaeli Peninsula, yielded graptolites of the middle part of the Wenlock – Cyrtograptus lundgreni Zone and possibly Upper Cy. rigidus-Cy. perneri Zone. This is the first record of graptolitic shale facies rocks in the Kocaeli Peninsula. The succession described is more akin to the Silurian of the Zonguldak Terrane than the shallow-marine carbonate facies of the Istanbul Terrane. It is therefore suggested that the contact between the Istanbul and Zonguldak terranes should be located to the west of Izmit (Derince).
