Türkiye Jeoloji Bülteni

Evolving from Supra-Detachment to Rift Basin in Rolling Hinge Model of the Büyük Menderes Graben

Abstract: Two types of basins developed in the Western Anatolian extensional tectonic system during the MioceneQuaternary interval, supra-detachment and rift basins, in the form of a rolling-hinge mechanism. In this study,stratigraphic and structural data on the presence of a rolling-hinge model in the area between Buharkent-Buldan onthe northern edge of the Büyük Menderes Graben are presented for the first time and the geological evolution of thegraben is discussed. In the light of obtained field data, the Miocene-Quaternary sequences deposited on the northernedge of the Büyük Menderes Graben were evaluated under 4 main sedimentary packages, which are separated fromeach other by angular and/or intrabasinal unconformities. These are the Lower-Middle Miocene (1st Package) and the Middle-Upper Miocene (2nd Package) which were deposited in the supra-detachment basin, and the PlioQuaternary 3rd and 4th packages formed in the rift basin. The structural elements that provide the basin formationand deformation of the region are the Miocene Büyük Menderes Detachment Fault, the Pio-Quaternary GökdereFault, and the Holocene Buharkent Fault Segment that cuts the youngest graben basin-fill located in the most easternpart of the Büyük Menderes Fault System.The main fault contacts of the supra-detachment basins characterizing the Miocene period are represented bya structural boundary of gneisses and schists belonging to the Menderes Massif, which is a relict of the effectivecompressional tectonic products of the Eocene–Oligocene interval.Due to the effectiveness of low-angle faults in the Menderes Massif until the end of Pliocene, a high rate ofextension occurred; because of this, the crust thickness was reduced. As a result of cooling of the crust duringQuaternary, the supra-detachment basin system was replaced by a rift system and the Menderes Massif was dividedinto blocks along the high-angle boundary faults of the rift basin. Field observations and kinematic analysis revealthat tectonic structures on the northern margin of the Büyük Menderes Graben evolved from low-angle to high-anglenormal faulting, and were rejuvenated southward parallel to the basin propagation in a rolling-hinge model. Thus,the basin formation also evolved from being supra-detachment to the rift type.