Comment on ‘Rockfall avalance deposits associated with normal faulting in the NW of the Çankırı basin: implications for the post‐collisional tectonic evolution of the Neo‐Tethyan suture zone’ by G. Seyitoğlu, N. Kazancı, L. Karadenizli, Ş. Şen, B. Varol, and T. Karabıyıkoğlu
Authors: Kaymakçı Nuretdin 
Published: December 2004

ABSTRACT
Seyitoğlu et al. (2000) described their interpretation, based on a single fault surface and rockfall avalanche deposits previously mapped as a W‐vergent thrust klippen above the Neogene successions in the Hançılı Basin, that in central Anatolia there was a single extensional basin throughout the Miocene – Early Pliocene. It was later fragmented by a structural high of Neo‐Tethyan ophiolitic basement bounded by an E‐vergent thrust fault in the east along the western margin of the Çankırı Basin and a west‐dipping normal fault in the west along the eastern margin of the Hançılı Basin, into two sub‐basins –Çankırı and Hançılı basins – subsequent to the activity along the Kırıkkale–Erbaa splay of the North Anatolian Fault Zone in the Late Pliocene (Fig. 1b). They also concluded that the crustal extension commenced in the Early Miocene and continued until the Early Pliocene without a break. They further claimed that their contention is supported by the recent works of Kaymakçı (2000) and Kaymakçıet al. (2000).

(a) Neotethyan sutures and microcontinents involved in the evolution of Turkey (modified from Şengör et al., 1984).

(b) Simplified geological outline of the Çankırı and Hançılı basins. ESFZ: Ezinepazarı–Sungurlu Fault zone; NAFZ: North Anatolian Fault Zone; STFZ: Sivritepe Fault Zone; YFFZ: Yağbasan–Faraşlı Fault Zone (modified from Kaymakçıet al., 2000). (c) Generalized stratigraphic column for the Çankırı and Hançılı basins. Note there are no contact relationships between the lithologies of the Çankırı and Hançılı basins.

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The western Margin of the Çankırı Basin lies within the İzmir–Ankara–Erzican Suture Zone, along which the Kırşehir Block in the south and the Sakarya Continent in the north collided during northward subduction of the intervening Neotethyan ocean crust under the Pontides during the Late Cretaceous to Early Tertiary (e.g. Şengör and Yılmaz, 1981;Görür et al., 1984; Koçyiğit et al., 1995; A. A. Dellaloğlu et al., unpublished report). The late Tertiary stratigraphy of Turkey has not been established yet because of insufficient fossil records and the predominance of continental sediments. The established stratigraphy is mostly based on superposition and/or palynomorphs (e.g. Koçyiğit et al., 1995) and therefore there are numerous points of view among scientists. The problem has become even worst with use of selective data collection in the field and selective use of available literature (Seyitoğlu et al., 2000). Seyitoğlu et al. (2000) claimed that the recent works of Kaymakçı (2000) and Kaymakçıet al. (2000) support their contention that central Anatolia experienced an orogenic collapse‐induced crustal extension during the Early Miocene – Early Pliocene; we feel this is a misinterpretation of ours and others work. I therefore would like to take this opportunity: (1) to describe the main difficulties with the field data, selective use of the literature and the interpretations made by Seyitoğlu et al. (2000); (2) to request clarifications and additional explanations to some points raised by them; and (3) to discuss the evolution of the western Margin of the Çankırı Basin.