Contrasting metamorphic evolution of metasedimentary rocks from the Çine and Selimiye nappes in the Anatolide belt, western Turkey

Abstract

P–T conditions, mineral isograds, the relation of the latter to foliation planes and kinematic indicators are used to elucidate the tectonic nature and evolution of a shear zone in an orogen exhumed from mid‐crustal depths in western Turkey. Furthermore, we discuss whether simple monometamorphic fabrics of rock units from different nappes result from one single orogeny or are related to different orogenies. Metasedimentary rocks from the Çine and Selimiye nappes at the southern rim of the Anatolide belt of western Turkey record different metamorphic evolutions. The Eocene Selimiye shear zone separates both nappes. Metasedimentary rocks from the Çine nappe underneath the Selimiye shear zone record maximum P–T conditions of about 7 kbar and >550 °C. Metasedimentary rocks from the overlying Selimiye nappe have maximum P–T conditions of 4 kbar and c. 525 °C near the base of the nappe. Kinematic indicators in both nappes are related to movement on the Selimiye shear zone and consistently show a top‐S shear sense. Metamorphic grade in the Selimiye nappe decreases structurally upwards as indicated by mineral isograds defining the garnet‐chlorite zone at the base, the chloritoid‐biotite zone and the biotite‐chlorite zone at the top of the nappe. The mineral isograds in the Selimiye nappe run parallel to the regional SR foliation, parallel the Selimiye shear zone and indicate that the Selimiye shear zone formed during this prograde greenschist to lower amphibolite facies metamorphic event but remained active after the peak of metamorphism. 40Ar/39Ar mica ages and the tectonometamorphic relationship with the Eocene Cyclades–Menderes thrust, which occurs above the Selimiye nappe in the study area, suggests an Eocene age of metamorphism in the Selimiye nappe. Metasedimentary rocks of the Çine nappe 20–30 km north of the Selimiye shear zone record maximum P–T conditions of 8–11 kbar and 600–650 °C. An age of about 550 Ma is indicated for amphibolite facies metamorphism and associated top‐N shear in the orthogneiss of the Çine nappe. Our study shows that simple monophase tectonometamorphic fabrics do not always indicate a simple orogenic development of a nappe stack. Preservation in some areas and complete overprinting of those fabrics in other areas apparently occur very heterogeneously.

Tectonic denudation of a Late Cretaceous–Tertiary collisional belt: regionally symmetric cooling patterns and their relation to extensional faults in the Anatolide belt of western Turkey

“…Hetzel & Reischmann (1996) showed that 40 Ar/ 39 Ar muscovite ages of 35-43 Ma constrain slow Eocene cooling during and after movement at the Selimiye shear zone. Subsequently, Ring et al (1999a), Gessner et al (2001c and Régnier et al (2003) supplied Figure 1. Simplified tectonic map of Anatolide belt in western Turkey (this region is traditionally referred to as Menderes Massif ); subdivison of region into three submassifs (Gördes submassif,Ödemiş submassif, which occupies same area as the Central Menderes metamorphic core complex, and Ç ine submassif) follows Şengör (1987).…”

“…The Selimiye nappe contains Palaeozoic metapelite, metabasite and marble (Schuiling, 1962;Ç aǧlayan et al 1980;Loos & Reischmann, 1999;Régnier et al 2003). Most of the Ç ine nappe consists of deformed orthogneiss, largely undeformed metagranite and minor pelitic gneiss, eclogite and amphibolite.…”

“…• C (Whitney & Bozkurt, 2002;Régnier et al 2003). Triassic granite in the Bozdaǧ nappe south of Alaşehir also contains garnet.…”

“…Collins & Robertson (1998) proposed that reactivation was due to top-to-the-E extensional faulting. Régnier et al (2003) showed that stretching lineations indicative of tectonic transport within a narrow zone underneath the base of the Lycian nappes were passively rotated from a N-S into an E-W direction suggesting that the top-to-the-E shearsense indicators are rotated top-to-the-S structures. Below we will show that the cooling pattern in the southern Ç ine nappe is also not compatible with topto-the-E extensional faulting.…”

Along-strike variations in the Hellenide Anatolide orogen: A tale of different lithospheres and consequences

“…The Menderes Nappes consists of four individual nappes, which, and this is an important point of our review, do not show any signs for a high-pressure overprint (Ring et al, 2001). It is important to note that detailed studies by various groups has demonstrated that the entire sequence below the two magneisocarpholite-kyanite-chloritoid bearing rocks does not show any relics for a high pressure overprint (Regnier et al, 2003), indicating that most probably the entire Menderes Nappes did not undergo high-pressure metamorphism.…”