'Middle East Technical University, Faculty of Architecture'
Abstract
Erdoğmuş-Yenigediz graben is one of the major structural elements of Akşehir-Simav Fault System (ASFS), which is a major extensional structure in the southwestern Anatolian extensional neotectonic province (SWAEP). It is about 6-10-km-wide, 15-km-long and approximately ENE-trending and is actively growing structure as indicated by the 1970.03.28 (Mw= 7.2) Gediz earthquake. The graben is characterized by two distinct units, separated by an angular unconformity: (i) Miocene-middle Pliocene Arıca formation and (ii) Plio Quaternary Erdoğmuş formation. The former unit commences with a basal conglomerate above the basement rocks and is composed mainly of coal-bearing continental and lacustrine sediments with lava flows and pyroclastics, particularly common in the middle parts of the sequence. The volcanics are dated at 18.4 ± 0.1 Ma (Ar-Ar mica ages). They record evidence for two deformation phases as suggested by twosets of overprinting slickenlines, intense folding, thrust and strike-slip faulting. The Erdoğmuş formation commences with terrace conglomerates and is composed mainly of travertines, older and younger alluvial deposits, fan-apron sediments and the recent axial graben floor sediments. Kinematic analysis of the graben-bounding normal faults, growth faults within the graben-infill and those deforming the sediments are consistent with three distinct phases of deformation: (i) Miocene middle Pliocene extensional phase, (ii) interveining NE SW contractional phase and (iii) Plio-Quaternary extensional phase. The data also suggests a distributed stress field and a multi-directional recent extension in predominantly NNE–SSW, E–W and NE–SW directions. This is also consistent with available focal mechanism solutions for the region. The graben therefore has an episodic evolutionary history with two extensional phases and an intervening short-term contraction, as described in many different parts of the SWAEP. The latter phase of extension is considered as the part of Neotectonic regime, which therefore commenced by the Late Pliocene.Ph.D. - Doctoral Progra
