Tectonic significance of deformation patterns in granitoid rocks of the Menderes nappes, Anatolide belt, southwest Turkey

Abstract

Deformation fabrics in Proterozoic/Cambrian granitic rocks of the Þine nappe, and mid-Triassic granites of the Bozdag nappe constrain aspects of the tectonometamorphic evolution of the Menderes nappes of southwest Turkey. Based on intrusive contacts and structural criteria, the Proterozoic/Cambrian granitic rocks of the Þine nappe are subdivided into older orthogneisses and younger metagranites. The deformation history of the granitic rocks documents two major deformation events. An early, pre-Alpine deformation event (D PA ) during amphibolite-facies metamorphism affected only the orthogneisses and produced predominantly top-to-NE shear-sense indicators associated with a NE-trending stretching lineation. The younger metagranites are deformed both by isolated shear zones, and by a major shear zone along the southern boundary of the Þine submassif. We refer to this Alpine deformation event as D A3 . D A3 shear zones are associated with a N-trending stretching lineation, which formed during greenschistfacies metamorphism. Kinematic indicators associated with this stretching lineation reveal a top-to-south sense of shear. The greenschist-facies shear zones cut the amphibolite-facies structures in the orthogneisses. 207 Pb/ 206 Pb dating of magmatic zircons from a metagranite, which crosscuts orthogneiss containing amphibolite-facies top-to-NE shear-sense indicators, shows that D PA occurred before 547.21.0 Ma. Such an age is corroborated by the observation that mid-Triassic granites of the Þine and Bozdag nappes lack D PA structures. The younger, top-to-south fabrics formed most likely as a result of top-to-south Alpine nappe stacking during the collision of the Sakarya continent with Anatolia in the Eocene.

Kinematic reconstructions and magmatic evolution illuminating crustal and mantle dynamics of the eastern Mediterranean region since the late Cretaceous

“…~8 Ma) [Işik and Tekeli, 2001;Bozkurt et al, 2011]. In the southern Menderes massif, coeval top-to-the S extensional shear has also been recognized and volcanoclastic rocks were unconformably deposited in the early Miocene (figure 4) [Bozkurt and Satır, 2000;Gessner et al, 2001aGessner et al, , 2001b. From the middle Miocene to the late Miocene-Pliocene, exhumation was localized in the central Menderes massif along the top-to-the NE Alaşehir and the top-to-the S Büyük ductile-brittle detachments (figure 7) [Hetzel et al, 1995b;Gessner et al, 2001b;Lips et al, 2001;Thomson & Ring, 2006;van Hinsbergen et al, 2010b].…”

“…Migmatites associated with S-type granites have also been described in the cores of these metamorphic domes [Jansen and Schuiling, 1976;Lister et al, 1984;Okay and Satır, 2000b;Vanderhaeghe, 2004;Bozkurt et al, 2010;Kruckenberg et al, 2011;Laurent et al, 2015;Beaudoin et al, 2015]. These intrusions are exposed in the footwall of major detachments where they show strong foliation with extensional kinematic indicators as well as cataclastic zones at the contact with the detachments [Faure and Bonneau, 1988;Gessner et al, 2001a;Iglseder et al, 2009;Denèle et al, 2011;Rabillard et al, 2015]. They were emplaced first in the northeastern Menderes massif with the Egrigöz and Koyunoba plutons both dated at ~21 Ma (UPb crystallization ages on zircon) in the footwall of the Simav detachment [Ring and Collins, 2005].…”

“…Syntectonic sediments started to be deposited in the hanging wall of these extensional structures [Photiades, 2002;Sánchez-Gómez et al, 2002;Kuhlemann et al, 2004;Lecomte et al, 2010;Laurent et al, 2015]. Further east, the exhumation of the Menderes massif was accommodated in the north by the top-to-the N Simav detachment recording at least ~50 km of displacement [Işik and Tekeli, 2001;Bozkurt et al, 2011] and in the south by a top-to-the S shearing just below the overlying Lycian nappes (figures 10 and 11) [Bozkurt and Satır, 2000;Gessner et al, 2001a;. Volcanoclastic rocks unconformably covering the southern Menderes massif indicate surface exposure of these metamorphic rocks in the early Miocene [Bozkurt and Satır, 2000].…”

“…At the same time, numerous syn-tectonic intrusive bodies were emplaced in the footwalls of detachment systems in the central Menderes massif and the Cyclades [Faure and Bonneau, 1988;Gessner et al, 2001a;Iglseder et al, 2009;Lecomte et al, 2010;Denèle et al, 2011;Laurent et al, 2015;Rabillard et al, 2015].…”

“…Ring et al, 1999b;Bozkurt & Oberhänsli, 2001;Gessner et al, 2001aGessner et al, , 2013Jolivet et al, 2004b]. Following this accretionary event, this massif has been exhumed in a back-arc extensional context, forming a dome-like structure [e.g.…”