Research Information System
GEODINAMICA ACTA, vol.29, no.1, pp.70-90, 2017 (SCI-Expanded)
The Kemalpasa Basin is one of the Quaternary basins in Western Anatolia and represents the south-western branch of the Gediz Graben system in this extensional province. This basin has been formed under the NNE-SSW trending extensional tectonic regime. It is bounded by a major fault, the Kemalpasa Fault, in the south and it is bounded by a number of downstepping faults, called as Spildagi Fault Zone, in the north. Both margin-bounding faults of the Kemalpasa Basin are oblique-slip normal faults. In order to better understand the activities of these faults, we investigated the tectonic geomorphology of the Kemalpasa Basin and interpreted the effect of tectonic activity on the geomorphological evolution using geomorphic markers such as drainage basin patterns, facet geometries and morphometric indices such as hypsometric curves and integral (HI), basin shape index (B-s), valley floor width-to-height ratio (V-f) and mountain front sinuosity (S-mf). The morphometric analysis of 30 drainage basins in total and mountain fronts bounding the basin from both sides suggests a relatively high degree of tectonic activity. The mountain front sinuosity (Smf) generally varies from 1.1 to 1.3 in both sides of the basin suggesting the active fronts and facet slopes (12 degrees-32 degrees) suggest a relatively high degree of activity along the both sides of the Kemalpasa Basin. Similarly, the valley floor width-to-height ratios (V-f) obtained from the both sides indicate low values varying from 0.043 to 0.92, which are typical values (<1) for tectonically active mountain fronts. The all values obtained are lower for the southern side. Therefore, we suggest that the tectonic activity of the Kemalpasa Fault higher than the Spildagi Fault Zone. This difference that can be arised from the different uplift rates also reveals the typical asymmetric characteristics of the Kemalpasa Basin. Additionally, the trapezoidal facets which have been observed on the southern side of the basin indicate that the Kemalpasa Fault is evolutionally more active as compared to the Spildagi Fault Zone. The geomorphic indices indicate that the Quaternary landscape evolution of the Kemalpasa Basin was governed by tectonic and erosional processes, and also the all results of morphometric analysis suggest a relatively high degree of tectonic activity along the faults bounding the Kemalpasa Basin. Moreover, considering that active large normal faults with an average 15 km long can cause major earthquake, the earthquake hazard in the Kemalpasa Basin should be investigated in detailed paleoseismological studies.