Geomorphology of Hereke-Körfez area and its relation to the submarine morphology of the centre basin of the Gulf of Izmit
A. Evren Erginal, T. Ahmet Ertek
Istanbul University, Faculty of Literature Department of Geography, Laleli, Istanbul,TURKEY
The present study is an attempt to interpret the geomorphology of the Hereke-Körfez area and the submarine morphology of the Gulf of Izmit. Geomorphological investigations have been carried out on the E-W trending normal fault, Hereke-Körfez fault, which constitutes the northern segment of North Anatolian Fault (NAF). Along this 10 km-long zone, the morphological features of this area have been considered according to the neotectonic features within and around the stream basins. Fault facettas, stream captures, deep dissection in young valleys, hanging valleys, en-echelon erosional surfaces, convexity and slope breaks in thalweg profiles indicate the youth phase in fluvvial geomorphological evolution. Active submarine landslides in front of the submarine deltas and the en-echelon erosional surface located at – 40 m to – 160 m imply the active tectonic in the Gulf of Izmit. The morphometric features of erosional surfaces indicate a collapse of about 190 m in the gulf. This result is supported by the deep valley form in the depression. It is concluded that this buried valley has been deepened by the en-echelon faultings. The aluvvial cones developed along the Hereke-Körfez Fault. That there is no marine terrace in this zone appears to be related to the sediment input from north by the creeks, which covered the marine terraces probably. These terraces might have later been deepened by en-echelon faultings. Thus, the deep drill holes are needed to find out the vertical cross-section of these young deposits. This will also reveal if the en-echelon erosional surfaces have been deformed by the activity of NAF. Consequently, the hinterland morphology of the Gulf of Izmit could well be used as a reliable criteria to assess the morpho-tectonic features in this coastal area.
Keywords: North Anatolian Fault, Izmit Bay, neotectonic movements, fluvial geomorphology