Morphotectonic characteristics and morphometric analysis of the Ecemiş Fault

Abstract

The Anatolian block, which is pushed by the collision between Arabia and Eurasia, started to escape westward in the Miocene by the North Anatolian Fault and its conjugate the East Anatolian Fault. Ecemiş fault crosses the escaping Anatolia block’s middle part in NE-SW direction as an inner block fault. Ecemiş fault extends 300 km from Mersin in the south to Kayseri in the north with 80±10 km total offset and at the same time it separates the Taurides into Eastern and Middle Taurides. Fault bounds important morphological features such as Sultansazlığı basin in the north, Aladağ mountain range in the east, Niğde Massive, Ulukışla basin and Bolkar mountain range in the west. Although the age of the Ecemiş fault, its activity and offset have been discussed by many others, its morphological analysis and characteristics remained unknown. Hence, main goal of this study is to define the morphotectonic characteristics of the Ecemiş fault and perform the analysis of morphometry. Morphological characteristics of the Ecemiş fault which have neotectonicaly importance are studied together with the analysis of aerial photos and digital elevation models beside the direct field observations. Some of characteristic features of landforms produced by active strike slip faulting are also observed along the Ecemiş Fault Zone – shutter rigdes, pressure ridges, deflected streams. Other important features are the large alluvial fans which developed at the front of Aladag Mountains. Ecemiş fault controls the formation of those fans. Two alluvium fans observed in the study area are quite wide although the streams which fed them are quite short. These two alluvial fans are Kelerdere alluvial fan, which lies between Sulucuova and Dündarlı village, and Demirkazık fan that lies between Demirkazık- Elekgölü villages. Most of the material of the fans is composed of Aladağ carbonate rocks. The origin of those fan deposits was derived from the high energy rivers as a result of the melting of the glaciers in the region. Those fans are influenced by the Ecemis fault zone. The present streams which developed on those fans are deflected and offset by the fault. The existence of the terraces in those two fans is related to the tectonic uplift of the region. Those terraces are cyclic. Rivers are buried in their own beds due to the changes at the bottom of the streams, and thus, cyclic terraces form. The main factor which creates the embedding is tectonic uplift of the region. The terraces in the study area are developed in three stages. 1/25.000 scaled topographic maps of Kayseri L34- d2, d3, Kozan M34 a1, a2, a4, d1, M33-c2, c3, N33- b2 are used in order to analyze the morphotectonic features, to map the Quaternary geology and the geometry of the fault zone. ArcView and ER Mapper softwares are used to obtain the digital elevation model. Digital elevation model is merged with the Landsat TM images by the ENVI software, in order to build the 3D topography of the study area. The morphological features observed in the 3D model are interpreted together with the field observations. Geomorphic indices are important quantitative measurements that are useful for identifying the level of an area’s tectonic activity. Because some geomorphic indices have been developed as basic reconnaissance tools to identify areas experiencing rapid or slow tectonic deformation. Hypsometric integral (E), Stream Length-gradient index (SL) and valley-floor width to valley height ratio (Vf) indices are applied in this study. Hypsometry is used in order to assess the geomorphologic stages. SL index exposes the final tectonic activity. Vf index differentiates between broad-floored canyons and V-shaped canyons. Eight main drainage basins in the vicinity of Ecemiş fault are selected for the morphometric analysis. These are, from north to south, Körköprü, Minas, Kocakapız, Fenk, Murt, Kazıklıaliboğazı, Deliboğazı and Çınarlı drainage basins. Selected drainage basins are gridded from the digital elevation model. The graphics of several geomorphic indices are obtained by using the River Tools software. According to the morphological analysis, it is identified that the geomorphologic features are developed by the Ecemiş fault and it has an important role in the evolution of morphology of the region. Analysis show that (1) the topography in the region is quite young, (2) there is active uplifting, (3) the tectonic avtivity which controls the uplift is still active.

Özet

Kuzeyde Erciyes Dağı (Kayseri) ile güneyde Mersin ili arasında K25°D doğrultusunda uzanan yaklaşık 300 km uzunluğundaki Ecemiş Fay Zonu Orta Anadolu’nun en önemli neotektonik unsurlarından biridir. Bu sol yönlü aktif doğrultu atımlı fay zonunun 80±10 km toplam atıma sahip olduğu tahmin edilmektedir. Saha gözlemlerinin yanı sıra hava fotoğrafı ve uydu görüntüleri üzerinde de bariz bir yapısal unsur olarak izlenen Ecemiş Fay Zonu boyunca sıralı tepeler, basınç sırtları, kaynaklar, ötelenmiş veya yön değiştirmiş dereler gibi doğrultu atımlı faylara özgü morfolojik unsurlar bulunmaktadır. Bu araştırmada Ecemiş Fay Zonu’nun oluşumuna yol açtığı bu morfolojik unsurların özellikleri saha çalışmalarının yanı sıra hava fotoğrafından ve sayısal arazi modellerinden elde edilen veriler değerlendirilerek araştırılmıştır. Böylece bölgenin morfotektonik evriminde Ecemiş Fay Zonu’nun etkisinin belirlenmesi amaçlanmıştır. Bu amaç çerçevesinde inceleme alanı içerisinde Ecemiş Fayı’na yakın ya da doğrudan fay tarafından etkilenmiş olan sekiz adet drenaj alanı seçilerek morfometrik analizler yapılmıştır. Bunlar kuzeyden güneye doğru Körköprüi, Minas, Kocakapız, Fenk, Murt-Koraç-Çamlık, Kazıklıaliboğazı-Emliboğazı, Deliboğazın ve Çınarlı derelerinin drenaj havzalarıdır. Morfometrik analizler için inceleme alanının Sayısal Yükseklik Modeli üzerinde hipsometrik integral, vadi tabanı genişliğinin-vadi yüksekliğine oranı ve akarsu uzunluğu- Eğim İndeksi (SL) gibi jeomorfik indisler üretilerek yorumlanmıştır. Bu morfometrik analizler ile Ecemiş Fay Zonu’nun bölgenin gelişiminde temel etken olduğu, bunun yanı sıra kayaların litolojik ve yapısal özelliklerinden kaynaklanan davranışının da bölgenin morfolojik gelişiminde etkili olduğu belirlenmiştir. Morfometrik veriler inceleme alanının son derece genç bir topografyaya sahip olduğunu, bunun aktif bir yükselme etkisinde geliştiğini ve bu yükselmeyi sağlayan tektonik aktivitenin halen etkin olduğunu işaret etmektedir.