Abstract:

The Gediz delta plain is one of the widest (about 400 km2) coastal plains of the Western Anatolia. Its geological structure and paleogeographical development are rather complicated. Within the scope of this research, eight core drillings performed between Süzbeyli (village) and Menemen (town), which went down to 15-20 m in depth. First of all, sedimentological units and the Holocene stratigraphy were determined on the core profiles. Then, micropaleontological analyses of the samples taken from each units allowed us to understand the ecological characteristics and environment of each stratigraphical units. Thus, following the changes of the environment, paleogeographical development was determined. These were summarized on a cross-section between Süzbeyli and Menemen. Mainly four stratigraphical units were identified as: the pre-Holocene alluvial fan or flood deposits of the Gediz river in the northeast, shallow marine sediments of the Holocene transgression in the southwest, and deltaic (mainly topset) and flood sediments of the Middle-Late Holocene regressive sequence. The cross-section revealed that the rising sea in the Holocene did not cover the Gediz delta plain completely, instead, intruded only up to the northeastern vicinity of Seyrek village. After the end of rapid sea-level rise (in about last 7-6 thousand years), deltaic aggradation and progradation formed the coastal zone of the present delta plain. In addition to the core drillings along the line between Süzbeyli and Menemen, other drillings performed in the north, near Maltepe (village) and in the south, near Çiğli (western quarter of the City of İzmir). They were also evaluated in the same way. Especially the core drilling to the east of Maltepe showed that the rising sea in the Holocene intruded more towards the east in the north of the delta plain. However, all of these are not enough to illuminate the paleogeographical development of the whole delta, and a comprehensive research project is necessary to collect available document and provide new necessary data. Keywords: Alluvial geomorphology, Paleogeography, Gediz delta-flood plain, İzmir.