Gürol Seyitoğlu

The role of the flexural rotation/rolling hinge model in the tectonic evolution of the Alasehir graben, western Turkey

The Alasehir graben is a well-defined prominent extensional structure in western Turkey, generally trending E–W and containing four sedimentary units. At the beginning of graben formation during Early–Middle Miocene times, the first fault system was active and responsible for the accumulation of the first and second sedimentary units. In Pliocene times, a second fault system developed in the hanging wall of the first system and a third sedimentary unit was deposited. The recently active third fault system separates older graben fill and a fourth sedimentary unit. Activity on each fault system caused the rotation and uplift of previous systems, similar to the ‘flexural rotation/rolling hinge’ model, but our field observations indicate that the rotated first fault system is also active, allowing exhumation of larger amounts of rock units. This paper documents that graben formation in western Turkey is a sequential process. Its different periods are represented by three fault systems and associated sedimentation. Consequently, recent claims using age data from only the second and/or third sedimentary units to determine the timing of graben formation are misleading.

Extensional folding in the Alaşehir (Gediz) graben, western Turkey

The broad folds exposed in the syn-extensional sedimentary rocks of the Alaşehir graben, western Turkey, have been recently interpreted as contractional in origin. Our field mapping of these folds suggests that they are the products of extensional tectonics. The field evidence includes the presence of several longitudinal extensional folds such as a rollover anticline and drag folds that are related to normal faults in the area. The extensional nature of these folds negates the previous interpretation and consequently suggests extensional tectonics in the region was not interrupted by short-lived contractional tectonics.

Neotectonics of the Zanjan-Kazvin area, Central Iran: Left lateral strike‐slip induced restraining stepovers

* Correspondence: moosarreza@hotmail.com

Afyon-Akşehir Grabeni Batı Kenarının Tektonik Özellikleri Üzerine Jeolojik ve Jeofizik Gözlemler: İki Evreli Genişleme Modeli Hakkındaki Tartışmalara Bir Katkı

Afyon-Aksehir Grabeni’nin bati kenarini olusturan, baskalasim temel kayaclari ile Neojen cokel kayaclari arasindaki KB-GD dogrultulu tektonik dokanak bir grup arastirmaci tarafindan Sultandagi Fayi olarak isimlendirilmis ve ters fay olarak yorumlanmis, diger bir grup tarafindan ise sinirin normal fay oldugu ileri surulmustur. Bazi arastirmacilar da Sultandagi Fayi’ni normal fay olarak kabul etmekle birlikte, bu fay tarafindan kesilen daha eski Yakasenek Ters Fayi’ni tanimlamislardir. Bu calismada soz konusu Yakasenek Ters Fayi uzerinde jeolojik ve jeofizik calismalar gerceklestirilmistir. Temel birimler ile Neojen birimler arasindaki dokanak uzerinde uygulanan ‘Sismik Isin Yonlendirme’ yontemi ile Yakasenek Ters Fayi’na karsilik gelen tektonik hat kuzeydoguya egimli olarak belirlenmistir. Buradaki fayin guneybatinin aksine kuzeydoguya egimli olarak saptanmasi, bolgede Miyosen-Pliyosen’de sikismanin varligini ortaya koyan ve iki evreli graben modelini destekleyen Yakasenek Ters Fayi’nin bulunmadigini gostermistir. Bolgede yapilan arazi gozlemlerinde de ters faya yonelik herhangi bir veriye rastlanmamistir