Shallow and Deep Structure of a Supradetachment Basin Based on Geological, Conventional Deep Seismic Reflection Sections and Gravity Data in the Buyuk Menderes Graben, Western Anatolia

Abstract

The Buyuk Menderes Graben is a depression in the Menderes core complex of western Turkey. The region is one of the most rapidly deforming regions of continental crust in the world and has exceptionally high seismic activity. In this study, shallow and deep seismic studies were conducted at the Buyuk Menderes graben. These studies included surface geological mapping and two seismic reflection sections. Detailed modelling was performed with the seismic study. In addition to these, a moving windows power spectrum was applied to the Bouguer gravity profile data of the study area. Since no deep well is available in this area, the geological interpretation of the seismic stratigraphy is based on the correlation with the surface geology, this was combined with the major reflections and the seismic facies observed along the profiles, and, thus, four main seismic units can be distinguished in the basin fill. Structural features of the basin is driven by a complex extensional faults system, consisting of a low-angle, S-dipping Buyuk Menderes detachment and by its synthetic and antithetic splays, bordering the opposite flanks of the basin. As a result of conventional deep seismic reflection sections and gravity data, three layers were defined in the study area. The first layer occurs at a thickness of 6 km, and the second layer is between 13 and 18 km. The third layer is at *33 km and may also G. Ç ifçi (emphasize Moho depth. The Buyuk Menderes graben has three clear reflectors which are base sediments, brittle-ductile transition, Moho and faults that show a half-graben floored by a detachment. The Moho depth is comparable with previous estimates. According to the results obtained, Bouguer gravity and seismic results are very much consistent with each other. It was observed that at the depths determined from seismic and gravity data, the distribution percentage of earthquake focal depths also rises.

Map view restoration of Aegean–West Anatolian accretion and extension since the Eocene

“…Finally, the West Anatolian Taurides and overlying ophiolites in southwestern Turkey were crosscut by several high‐angle normal faults [e.g., Alçiçek , 2010], which we do not reconstruct in detail. We restore minor, i.e., 3 km, N‐S extension since 5 Ma associated with the Büyük Menderes and Gediz grabens, following the studies by Çiftçi and Bozkurt [2010] and Çifçi et al [2011].…”

Supradetachment basin evolution during continental extension: The Aegean province of western Anatolia, Turkey

“…3). Together with the Büyük Menderes basin to the south (Gürer et al, 2009), it is one of the two main pre-Quaternary basins in the Central Menderes Massif that evolved in the hanging walls of major detachment faults (Sözbilir, 2002;Gürer et al, 2009;Çiftçi and Bozkurt, 2009aÇiftçi and Bozkurt, , 2009bÇiftçi and Bozkurt, , 2010Çiftçi et al, 2011). Its internal structure is strongly controlled by the kine matics of the WNW-ESE-oriented extensional normal fault systems and the NNE-SSW-running, oblique-slip hinge faults (Figs.…”

“…1), and its internal structure, metamorphism, pressure-temperature-time (P-T-t) history, and geochronology have been relatively well documented (Satir and Friedrichsen, 1986;Hetzel et al, 1995aHetzel et al, , 1995bRing et al, 1999b;Gessner et al, 2001aGessner et al, , 2001bIşik and Tekeli, 2001;Lips et al, 2001;Okay, 2001;van Hinsbergen, 2010). However, the literature on the occurrence and documentation of supradetachGeological Society of America Bulletin, November/December 2011 ment basins in the broader Aegean extensional province of western Turkey is rather limited (i.e., Sözbilir, 2002;Sözbilir et al, 2010;Çiftçi et al, 2011), in part because structural, sedimentological, and other physical characteristic features of such basins have not been recognized in this region. The fi ndings of this study provide signifi cant insights for our understanding of supra detachment basin formation in continental extension environments in general and in the Aegean province in particular, and they present a special case for fault-controlled segmentation of supradetachment basins.…”

Structure of the Büyük Menderes Graben systems from gravity anomalies

“…It is possible to separate the probable effects of shallow and deeper structures by using second vertical derivatives (SVDs) (Kearey et al, 2002). SVD calculations have been widely used to enhance local anomalies obscured Bozkurt and Park, 1994;Bozkurt, 2001;Sözbilir, 2001Sözbilir, , 2005Işık et al, 2003;Özer and Sözbilir, 2003;Bozkurt and Sözbilir, 2004;Çifçi et al, 2011). by broader regional trends and to aid in the definition of the edges of source bodies.…”