Genç tektonik hareketlerin kontrolünde gelişmiş olan Gençali Fayı'nın tektonik jeomorfoloji özelliklerinin saptanması çalışmanın başlıca amacını teşkil eder. Bu amaç doğrultusunda jeolojik tarihçe boyunca sahada meydana gelen tektonik hareketler ile aşındırma etmen ve süreçlerinin etkinlik derecesi mevcut literatür ve arazi çalışmaları ışığında araştırılmıştır. Bu çalışmada öncelikle Gençali Fayının geçtiği sahanın genel fiziki coğrafya özellikleri belirlenmiş, daha sonra ise sahanın 1/25 000 ölçekli jeoloji ve diri fay haritaları yardımıyla litolojik ve tektonik özellikleri incelenerek bölgedeki neotektonik üniteler ayırtedilmiş, bunların genç faylarla olan ilişkileri ortaya konulmuştur. Çalışmada; dağlık arazilerin nasıl yükseldiği ve parçalandığı, fayın yaşı ve etkinliği, ovalık alanların oluşumunda fay hattının etkisi, akarsu ağının oluşum ve gelişimi ile sahadaki etkinlik durumu, sahadaki deltaların nasıl meydana geldiği, aşınım yüzeylerinin tespiti ve sahadaki dağılışı değerlendirilmiş ve saha döngü bakımından yaşlandırılmıştır. Araştırma sahasının ana morfolojik görünümü, tektonik aktivitenin kontrolünde şekillenmiştir. Jenetik bakımdan flüvyal koşulların etkin olduğu bu saha, esas itibariyle iç dinamiklerce şekillendirilmiştir. Özellikle Neotektonik dönem ve bu dönemin kratonik stili sahada daha çok kırılma ve faylanmalara neden olmuş, böylece faylı yapıya ait görüntü ortaya çıkmıştır. Çalışmada veri girişi ve analiz işlemleri için ArcGIS 10.2 programı ve CBS kullanılarak araştırma sahasının lokasyon, jeoloji, rölyef, eğim, bakı, topografya, fay ve deprem haritaları oluşturulmuştur. Araştırma sahasının jeomorfoloji haritası ise Adobe Photoshop CS3 Portable kullanılarak çizilmiştir. Elde edilen veriler 2014 yılının farklı tarihlerinde yapılan arazi çalışmalarıyla değerlendirilmiş ve bu esnada araştırma sahasına ait fotoğraflar bir kısmı havadan bir kısmı karadan çekilmiştir. Yer şekilleri üzerinde neotektonik dönemin izlerine araştırma sahasının birçok yerinde rastlamak mümkündür. Paleotektonik dönemde oluşan yer şekillerinin izleri olmakla birlikte bu şekiller ya Orta Miyosen de başlayıp günümüzde de devam eden neotektonik

The main aim of this study is to determine the tectonic geomorphologic features of Gençali Fault developed under the control of young tectonic movements. In accordance with this aim, the tectonic movements and abrasion factors and processes of effectiveness level emerging throughout geological history were investigated in consideration of present literature and field studies. In this study, the general physical geographic features of the field where Gençali Fault goes past were determined primarily, following a differentiation of neotectonic units in the region through the analysis of lithological and tectonic features by means of 1/25 000 scaled geological and active fault maps, and their relation with new fault lines were asserted. The study includes the evaluation of how mountainous terrains rise and disintegrate, the age and activeness of the fault, the effect of fault lines in the formation of plains, the formation of the river systems, their improvements and effects on the field, how deltas are formed, the determination of erosion surface and their dispersion in the field, and the ageing of the field in terms of cycles. The main morphologic expression of the field was shaped in control of the tectonic activity. This field, where genetically fluvial conditions are effective, is shaped virtually by internal dynamics. Especially the neo-tectonic period and its cratonic feature caused to fraction and faulting, thus the image of faulted structure emerged. In this study, ArcGIS 10.2 programme and CBS were used for data input and analysis, and location, geology, relief, slope, exposure, topography, fault and earthquake maps were drawn accordingly. The geomorphology map of the studied field was drawn via Adobe Photoshop CS3 Portable. The obtained data was evaluated through field studies at different dates in 2014 and in the meantime, the photos of the field were taken both aerial and overland. In many fieldwork, it is possible to discover the trace of the period of neotectonic on the landforms. As well as being the trace of the forms of neotectonic formed at paleotectonic period, those landforms either 776 Halid PEKTEZEL Turkish Studies International Periodical For the Languages, Literature and History of Turkish or Turkic Volume 10/2 Winter 2015 are formed with the movement that has started in the middle of miocene or covered and eroded due to the effect of denudational process. Thera are also evidence that shows tectonic movements accured in paleotectonic period. However, they almost lost their direct effect on landforms that we observe today. Vertical and strike slip faults, fault slopes, fault steps, tectonic slopes, fault lines, linelike dales, antecedant bospourus, tectonic downs, offset streams, linear backs, river gazebos, facets in fieldwork are occured with neotectonic movements and the process of fluvialis. Because of those neotectonic movements paleotectonic surfaces rise at some places (Gürle Mounts), warp or cause lowlands (Engürücük Lowland) through breaking down. Forms that occured with tectonic movements and the process of fluvialis are shown on the map of goemorphology. Gençali Faults existing in Marmara region is a small part of North Anatolia Fault (KAFZ) Zone. This fault line takes its form under the influence of D – B oriented jam, K – G oriented strain and ground to ground boarden regime with the effect of KAFZ. Structurel forms connected to tectonic fault constitute the main relief in fieldwork. Topography shaped by young faulting with the end of pliocence and post pliocence tectonic movement is at the stage of advance youth. The body of river and its development are associated with stated fault or its segments. Connected to poleotectonic and post poleotectonic movement, young fault blockeds and tectonic warps cause decay of river drainage and ruins the development of dale. Gençali Fault occurred as a result of tectonic movements at the end of Pliocene period. This fault has shifted Koca River and its most important branch Kurtul River by cutting them horizontally where they run north-wards (to Gemlik Bay) and changed their base. Both rivers have adapted to this tectonic elevation easily and sank to their terrain, creating typical antecedent straits (Kurtul and Muratoba). The elevation of the field as a result of tectonic movements at the end of Pliocene period and negative changes in the eustatic bottom level in early Pleistocene period caused the rivers to sink into their beds by causing head erosion and also caused typical bedrock terrace sets along principle valleys. There is not a possible dip-slip fault in the Map of Active Faults in Turkey which is prepared by Emre et al.(2012) under the supervision of General Dictatorate of Mineral Research and Exploration (we named this fault as Engücürük in our study). We think this fault should be placed in the Map of Active Faults in Turkey considering its location and geomorphologic qualities. Gençali Fault has a significant vertical-slip fault as well as being a right-lateral strike-slip fault. This fault has elevated the south block and lowered the north block. It led to the emergence of İznik basin of Gençali Fault and Gemlik Bay along with Gemlik Fault Zone. Likewise, Engürücük Plain was formed as a result of tectonic subsidence which occurred because of Umurbey Fault in the North, a possible Engürücük Fault in the East and Gençali Fault in the South. Gençali Fayı’nın (Bursa) Tektonik Jeomorfoloji Özellikler 777 Turkish Studies International Periodical For the Languages, Literature and History of Turkish or Turkic Volume 10/2 Winter 2015 The fact that earthquakes occur frequently around the study field is the evidence that Gençali Fault is still an active fault today and that the tectonic activity is still happening. As a result, while making new town planning and housing plans in the study field, this tectonic activity and soil properties of the area should be taken into consideration.