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

Abstract

We present a detailed structural and stratigraphic record of a Neogene-Quaternary supradetachment sedimentary succession in the Aegean extensional province of western Anatolia, and we compare its tectonic features and evolution to those of other well-documented supradetachment basins around the world. The sedimentary fill of the Alasehir basin records the uplift and exhumation of a core complex in the footwall of a detachment fault within the Central Menderes Massif. Accumulation of footwall-derived clastic sediments in this basin started ca. 20 Ma, shortly after the initiation of the approximately E-W-trending Alasehir detachment and its shear zone, and continued until ca. 2 Ma. Major sedimentary facies types include fl uvial and alluvial-fan deposits, debris-fl ow and mass-fl ow deposits, and locally developed lacustrine rocks. These sedimentary units were accumulated largely in distal depocenters within the extending basin, as the low-angle (15°-28°) detachment faulting created little accommodation space near the basin margins while producing high back-shed topography in the uplifted Menderes core complex. The drainage system was dominated mainly by extension-parallel transverse streams during the main phases of basin evolution. Extension-parallel, scissor (hinge) faulting produced differential uplift and subsidence in the adjacent fault blocks, changed the direction of sediment transport and drainage patterns over short distances, and resulted in the local uplift of the older basin strata. These processes led to the development of subbasins with lateral variations in basement topography, strata thickness, and sedimentary facies distribution, and generated a segmented basin archi tec ture. High-angle synthetic and antithetic faults that formed extensively after 3 Ma caused back-tilting of the sedimentary strata, formation of half grabens with their own axial drainage systems, and development of angular unconformities. With the onset of this crustal-scale block faulting, the detachment fault ceased to operate, and the Quaternary Gediz graben started to develop at the northern end of the Alasehir supra detachment basin. Our comparative evaluation of select basins shows a maximum sediment thickness of 3 km, average extension rates of 6 to 8-9 mm yr -1 , and accumulation rates of 0.1-0.2 mm yr -1 (uncorrected for compaction) in supra detachment basins in general. The rates and amounts of extension, the geom etry of detachment faulting, the rates of footwall uplift, and the kinematics and interplay of different fault systems are the most important factors controlling threedimensional structural architecture and evolution of supradetachment basins.For permission to copy, contact editing@geosociety.org

Tectonic geomorphology of the Kemalpaşa Basin and surrounding horsts, southwestern part of the Gediz Graben, Western Anatolia

“…However, suggest that this view is broadly supported by other studies into the two-stage evolution of the graben (e.g. Bozkurt & Sözbilir, 2004;Koçyiğit et al, 1999;Öner & Dilek, 2011;Purvis & Robertson, 2004).…”

“…This unit, is a NE-trending tectonic zone lying between the Menderes Massif and Izmir-Ankara Suture , has undergone Alpine deformation (Erdoğan, 1990;Okay & Siyako, 1993). Additionally, it is known that the Bornova Flysch Zone formed in a narrow basin between a strike-slip tear Koçyiğit et al, 1999;Öner & Dilek, 2011;Patton, 1992;Purvis & Robertson, 2004;Sözbilir, 2001Sözbilir, , 2002. According to Bozkurt and Sözbilir (2004), the Gediz Graben is the product of two extensional episodes that displayed differences in stress pattern and deformation styles.…”

Tectono-stratigraphy of the Neogene basins in Western Turkey: Implications for tectonic evolution of the Aegean Extended Region

“…These faults have also controlled the basins in the upper plate (e.g., Çemen et al, 2006;Çiftçi and Bozkurt, 2009;Öner and Dilek, 2013;Şen and Seyitoğlu, 2009;Sözbilir, 2002). The footwall of the GDF was intruded by the Salihli and Turgutlu granitoids (e.g., Hetzel et al, 1995;Glodny and Hetzel, 2007;Catlos et al, 2010).…”

Eocene Granitic Magmatism in NW Anatolia (Turkey) revisited: New implications from comparative zircon SHRIMP U–Pb and 40Ar–39Ar geochronology and isotope geochemistry on magma genesis and emplacement

“…The Kazdag and Menderes massifs represent Cenozoic metamorphic core complexes in the Aegean extensional province (Bozkurt and Park, 1994;Hetzel and Reischmann, 1996;Hetzel et al, 1995;Okay and Satır, 2000;van Hinsbergen et al, 2010), and consist of exhumed high-grade, lower-middle crustal rocks of the western Pontides and the Anatolide-Tauride Platform, respectively. These Cordilleran-type core complexes are overlain by supradetachment basin cover sequences and are intruded by syn-extensional granitoid plutons Bozkurt and Park, 1997;Gessner et al, 2004;Hetzel and Reischmann, 1996;Okay and Satır, 2000;Öner and Dilek, 2011).…”