Extensional v. contractional origin for the southern Menderes shear zone, SW Turkey: tectonic and metamorphic implications

Abstract

The southern Menderes Massif in southwest Turkey consists mainly of orthogneisses and overlying Palaeozoic-Middle Paleocene schists and marbles. The contact between the two distinct rock types is almost everywhere structural, herein named the southern Menderes shear zone: a S-facing, high-angle ductile shear zone that separates metamorphic rocks of differing grade. Although there is a consensus that the shear zone was associated with top-to-the-S-SSW shearing and is of Tertiary age, its origin and nature have been highly debated over the last decade. Some claim the contact is a thrust fault, while others have argued for an extensional shear zone. Integration of field and microstructural data (the identification of different fabrics, associated kinematics and overprinting relationships) with fissiontrack thermochronology and the P-T paths of the rocks above and below the shear zone, supports the conclusion that the southern Menderes shear zone is an extensional shear zone and not a thrust. The data are consistent with a model that the exhumation and cooling of the southern Menderes Massif occurred after a period of extensional deformation. Pervasive top-to-the-N-NNE high-temperature-mediumpressure ductile shear structures (D 2 deformation) overprint an early HP event (D 1 deformation). The subsequent top-to-the-S-SSW greenschist shear band foliation (D 3 deformation) developed mostly around the orthogniess-schist contact and forms the most characteristic features of the massif. The topto-the-N-NNE structures are attributed to the main Alpine constructional deformation that developed during back-thrusting of the Lycian nappes during the latest Palaeogene collision between the Sakarya continent and the Anatolide-Tauride platform across the Neotethyan Ocean. The top-to-the-S-SSW structures are interpreted to be the result of the exhumation of the massif during the activity of the southern Menderes shear zone. The presence of these two distinct fabrics with differing kinematics suggests that the southern Menderes shear zone operated as a top-to-the-N-NNE thrust fault during early Alpine contractional deformation but was later reactivated with an opposite sense of movement (top-to-the-S-SSW) during subsequent Oligocene-Miocene extensional collapse.

Field evidence for normal fault linkage and relay ramp evolution: the Kırkağaç Fault Zone, western Anatolia (Turkey)

“…Recent tomographic and seismic studies reveal that slab edge processes and related backarc extension are the dominant driving force for western Anatolian and Aegean tectonics (Biryol, Beck, Zandt, & Özaçar, 2011;Faccenna, Bellier, Martinod, Piromallo, & Regard, 2006;Gans, Beck, Zandt, Biryol, & Ozacar, 2009;Gessner, Gallardo, Markwitz, Ring, & Thomson, 2013;Jolivet et al, 2013;Uzel et al, 2015;van Hinsbergen, Hafkenscheid, Spakman, Meulenkamp, & Wortel, 2005;van Hinsbergen, Kaymakçı, Spakman, & Torsvik, 2010). The main characteristics of this regional extension are as follows: (i) E-W trending detachment faults (Bozkurt, 2006;Bozkurt & Sözbilir, 2004;Emre, 1996;Emre & Sözbilir, 1997;Hetzel, Passchier, & Ring, 1995;Hetzel, Ring, & Akal, 1995;Hetzel et al, 2013;Işık, Seyitoğlu, & Çemen, 2003;Lips, Cassard, Sözbilir, Yılmaz, & Wijbrans, 2001;Sözbilir, 2001), (ii) E-W trending high angle normal faults that cut and offset the detachments (Bozkurt, 2003(Bozkurt, , 2004(Bozkurt, , 2007Bozkurt & Park, 1994;Çiftçi & Bozkurt, 2009;Gessner et al, 2001;Hetzel, Romer, Candan, & Passchier, 1998;Işık & Tekeli, 2001;Işık, Tekeli, & Seyitoğlu, 2004;Işık et al, 2003;Kaymakci, 2006;Koçyiğit, Yusufoğlu, & Bozkurt, 1999;Okay & Satır, 2000;Özkaymak, Sözbilir, & Uzel, 2011;…”

The geodynamics of the Aegean and Anatolia: introduction

“…NAF, North Anatolian Fault; EAF, East (a) GPS horizontal velocities and their 95% confidence ellipses in a Eurasia-fixed reference frame for the period 1988-1997 superimposed on a shaded relief map derived from the GTOPO-30 Global Topography Data taken after USGS. Bathymetry data are derived from GEBCO/97-BODC, provided by GEBCO (1997) and Smith & Sandwell (1997a, b Avigad & Garfunkel 1989Okrusch & Bröcker 1990;Jolivet et al 1994Jolivet et al , 2003Avigad et al 1997;Bröcker et al 2004;Ring et al 2001;Trotet et al 2001;Bröcker & Pidgeon 2007 Gautier et al 2002;Whitney et al 2003;Ş engün et al 2006;Bozkurt 2007, and references therein).…”

“…Several core complexes (e.g. Rhodope, Cycladic, Kazdaǧ, Menderes, Niǧde core complexes: Lister et al 1984;Dinter & Royden 1993;Gautier et al 1993Gautier et al , 1999Bozkurt & Park 1994;Gautier & Brunn 1994;Dinter et al 1995;Vandenberg & Lister 1996;Hetzel et al 1998;Jolivet & Patriat 1999;Jolivet & Faccenna 2000;Lips et al 2001;Bonev & Stampfli 2003;Ring et al 2003;Gessner et al 2004;Beccaletto & Steiner 2005;Bonev 2006;Bonev et al 2006a, b;Bozkurt 2007;Régnier et al 2007, and references therein) and overprinting approximately east -west-trending grabens (e.g. Gulf of Corinth, Büyük Menderes and Gediz grabens) therefore form the most prominent elements of the AES.…”

Mineralogical characteristics of unusual “Anatolian” diaspore (zultanite) crystals from the İlbirdağı diasporite deposit, Turkey

“…A large metamorphic region, which was formed by regional metamorphism, called the Menderes massif is situated in the west and southwest regions of Turkey (Önay, 1949;Schuiling, 1962;Wippern, 1964;Bozkurt, 2007;Candan et al, 2007;Regnier et al, 2007). This metamorphic massif includes many metabauxite (diasporite and emery) deposits (Smith, 1850;Önay, 1949;Wippern, 1965;Graciansky, 1965;Özlü, 1983;Yalçın, 1987).…”