Development of the Kembos and Eynif structural poljes: Morphotectonic evolution of the Upper Manavgat River basin, central Taurides, Turkey Uğur Doğan a, ⁎, Ali Koçyiğit b , Ergin Gökkaya c a Department of Geography, Ankara University, 06100 Ankara, Turkey b Department of Geological Engineering, Active Tectonics and Earthquake Research Lab., Middle East Technical University, Ankara, Turkey c Social Science Institute, Ankara University, 06100 Ankara, Turkey abstract article info Article history: Received 7 May 2016 Received in revised form 19 October 2016 Accepted 19 October 2016 Available online 22 October 2016 The study area is the upper Manavgat River basin. It is located in the western part of the central Taurides. Two significant geomorphic features of this basin are the Kembos and Eynif structural poljes. This study focuses on the tectonic impacts on the development of poljes and the morphotectonic evolutionary history of the study re- gion. The data were obtained through a detailed mapping of the faults, rocks, and geomorphic features. The evolutionary history of the basin begins with the NW-SE–trending karstic paleovalleys, which first formed on the erosional surfaces that are part of the early and middle Miocene contractional tectonic regime. The tributaries, which developed under the influence of the NW-SE–trending Pliocene strike-slip faults, joined the main trunk of the Manavgat River. Starting at the beginning of the Quaternary, the tensional tectonic regime became promi- nent, and then a series of graben-horst structures appeared. The Eynif and Kembos poljes formed within two of these structures. The underground capture of surface water occurred in the grabens. The waters of both poljes drain through swallow holes into the Manavgat River and then in to the Mediterranean Sea. The regional uplift rates (the downcutting rates) are as follows: 0.36 mm/y in the late Miocene (Tortonian-Messinian), 0.06 mm/y in the Pliocene, and 0.18 mm/y in the Quaternary periods, which are based on the geopmorphic data obtained from high erosional surfaces and the Manavgat River valley. The average downcutting/uplift rate is 0.18 mm/y in this region. © 2016 Elsevier B.V. All rights reserved. Keywords: Central Taurides Manavgat River Polje Paleo-valley Tensional tectonic regime Uplift rate 1. Introduction Poljes are large closed depressions developed within karst terrains, with flat (alluviated) floors and karstic drainage (Sweeting, 1973; Ristic, 1976; Gams, 1978; White, 1988; Ford and Williams, 1989; Prohic et al., 1998; Doğan, 2003; Gracia et al., 2003). Cvijic (1893) pro- posed a minimum for the poljes floor of more than 1 km, whereas Gams (1978) considered the polje floors to be at least 400 m wide. Nonetheless, these suggestions appear to be arbitrary. Poljes, having at least one of their sides bounded by steep limestone slopes, are impor- tant intramountain plains where road networks, settlements, and agri- cultural activities tend to be concentrated. These depressions are generally elongated and their orientation runs parallel to the direction of the structural grain (Gracia et al., 2003). Isolated hills, so-called hums, protruding above the alluvial floor are characteristic features of poljes (Sweeting, 1973). In some poljes, ter- races or corrosional surfaces represent evidence of alternating phases of deepening and planation in the polje floor (Sweeting, 1973; White, 1988; Prohic et al., 1998; Gracia et al., 2003). The Jiloca polje in the Iberian Range, Spain, is one of the well-known examples of this type of polje (Gracia et al., 2003). Waters from karst springs may enter into a polje, flow along a surface stream, and percolate via swallow holes (ponors). Some poljes may be opened to external drainage from one end or both ends (Ristic, 1976). A general feature of many poljes is the periodical flooding of their floors during wet seasons either as a result of the rising water table and/or when the amount of water input enter- ing polje is higher than the drainage capacity of the swallow holes (Sweeting, 1973; White, 1988; Ford and Williams, 1989; Doğan, 1996, 2003; Gracia et al., 2003). Different views concerning the dominant factors that control the or- igin of poljes is a contentious issue at present. Numerous polje classifica- tions based on geomorphic and hydrologic characteristics clearly indicate the controversial nature of this subject (Gams, 1969, 1973, 1978; Ristic, 1976; Ford and Williams, 1989). Among these, the classifi- cation by Ford and Williams (1989), mainly derived from Gams (1978), differentiates three groups: termed as border, structural, and base level poljes. This classification provides valuable insight into the basic pro- cesses involved in the development of poljes. Neotectonic movements have long been known to play a significant role in the formation of poljes (Cvijic, 1893; Lehmann, 1959; Gams, 1978; Mijatovic, 1984; White, 1988; Julian and Nicod, 1989; Prohic Geomorphology 278 (2017) 105–120 ⁎ Corresponding author. E-mail addresses: geoankara@gmail.com, ugdogan@yahoo.com (U. Doğan). http://dx.doi.org/10.1016/j.geomorph.2016.10.030 0169-555X/© 2016 Elsevier B.V. All rights reserved. Contents lists available at ScienceDirect Geomorphology journal homepage: www.elsevier.com/locate/geomorph