A re-evaluation of the Eskişehir Fault Zone as a recent extensional structure in NW Turkey

• Published in: Journal of Asian earth sciences 2007-10, Vol.31 (2), p.91-103
• Main Author: Ocakoğlu, Faruk
• Format: Article
• Language: English
• Subjects: Eskişehir Fault Zone; Eskişehir graben; Extension; Geomorphology; Plio-Quaternary landscape; Turkey
• ISSN: 1367-9120; 1878-5786
• DOI: 10.1016/j.jseaes.2007.05.002

The Eskişehir Fault Zone (EFZ), one of the major active structures within the Anatolian platelet, is investigated in a 100 km long sector between Bozüyük and Alpu, in vicinity of Eskişehir. The morphotectonic observations indicate that throughout the studied area the EFZ extends WNWwards as a ca. 15 km wide belt, and is composed of some 21 fault segments, 5–25 km long. These segments form a north-dipping southern set and two south-dipping northern sets, all together working both sides of the Eskişehir graben. The faults are dominantly normal in character with a slight right-lateral component in the westernmost areas. The estimated total vertical displacement on certain northern and southern fault segments exceeds 450 m. In order to estimate the initiation age of the EFZ a brief stratigraphic review is given. The generally horizontal Pliocene terrestrial deposits are separated from the Miocene succession by a low-angular unconformity, and are cut in turn by the EFZ. Sedimentological data show that neither the distribution of the Pliocene depositional environments and their paleocurrent directions, nor the preserved Pliocene basal unconformity surface have a genetic relation to the EFZ. These data strongly suggest that the EFZ is a younger post-Pliocene active normal fault zone with low rates of deformation.