Talip Güngör

An active bivergent rolling-hinge detachment system: Central Menderes metamorphic core complex in western Turkey

Two symmetrically arranged detachment systems delimit the central Menderes metamorphic core complex and define a bivergent continental breakaway zone in the Anatolide belt of western Turkey. Structural analysis and apatite fission-track thermochronology show that a large east-trending syncline within the Alpine nappe stack in the central part of the orogen is related to late Miocene‐early Pliocene to recent core-complex formation. The syncline formed as a result of two opposite-facing rolling hinges in the footwalls of each of the two detachments. Back-rotation of the syncline limbs suggests that the detachments rotated from an initial dip of 408‐608 to a currently shallow orientation of 08‐208.

The Menderes Massif of western Turkey and the Cycladic Massif in the Aegean—do they really correlate?

Based on lithostratigraphic comparisons the Menderes Massif has been correlated with the Cycladic Massif, thereby implying that the eastern Mediterranean consists of a narrow pre-Alpine basement belt which is laterally continuous over a long distance and which experienced a similar Alpine orogenic history. Our work indicates that the architecture, the age of basement and the pre-Alpine and Alpine tectonometamorphic history of both massifs differ fundamentally from each other. The Menderes Massif consists of remnants of the Cycladic Massif which overly an exotic unit, the Menderes nappes. Both massifs do not represent lateral continuations which has implications for palaeogeographic reconstructions.

Structural and thermal history of poly-orogenic basement: U–Pb geochronology of granitoid rocks in the southern Menderes Massif, Western Turkey

Ion microprobe U–Pb dating of granitoid rocks from key structural outcrops of the Menderes Massif in western Turkey provides an important constraint to the thermal and deformational history of a structurally complex metamorphic belt within the Alpine chain. Crystallization ages of two granite protoliths, derived from the weighted means of rim ages and the ages of homogeneous prismatic zircon grains, are 541 ± 14 Ma and 566 ± 9 Ma, whereas the cores of zoned pyramidal and short-prismatic zircon grains range from Palaeoproterozoic to Neoproterozoic in age. These ages indicate that amphibolite- to granulite-facies metamorphic rocks in much of the Menderes Massif were deformed, metamorphosed and intruded during the Pan-African Orogeny, and neither crystallized nor remelted during an Alpine event. Structural and metamorphic evidence for Alpine convergence in Pan-African basement rocks is limited to greenschist-facies top-to-the-south shear zones, which occur on a regional scale across a number of tectonic units.

How to resist subduction: evidence for large-scale out-of-sequence thrusting during Eocene collision in western Turkey

Significant along-strike variations have locked large parts of the Alpine subduction complex in the Eastern Mediterranean in the Eocene, and defined the end of high-pressure accretion in western Turkey. Structural analysis reveals that the Anatolide belt in western Turkey formed under greenschist facies metamorphic conditions in the Eocene when a high-pressure metamorphic fragment of the Adriatic plate (the Cycladic blueschist unit) was thrust onto the imbricated mid-crustal units of the Anatolian microcontinent (the Menderes nappes). The contact between the Cycladic blueschist unit and the Menderes nappes, the Cyclades–Menderes thrust, represents an out-of-sequence ramp which cuts up-section towards the south. The lack of Alpine high-pressure fabrics below the Cyclades–Menderes thrust implies c.35 km of exhumation of the Cycladic blueschist prior to its Eocene emplacement on top of the Menderes nappes. Structure and geodynamic evolution of the Anatolide belt are in striking contrast to the neighbouring Aegean and contradict the model of a laterally continuous orogenic zone, in which the Anatolide microcontinent is interpreted as an eastern extension of the Adriatic plate.

Field Guide to Samos and the Menderes Massif: Along-Strike Variations in the Mediterranean Tethyan Orogen

This field-trip guide explores the tectonics of Samos and the Menderes Massif, two fascinating areas within the eastern Mediterranean section of the Tethyan orogen. The guide includes detailed outcrop descriptions, maps, and diagrams to explore along-strike variations in the Hellenide-Anatolide orogen, including the architecture of the Early Tertiary Alpine nappe stack and its strong Miocene extensional overprint. The suggested itinerary is based on the 2010 Geological Society of America Field Forum: “Significance of Along-Strike Variations for the 3-D Architecture of Orogens: The Hellenides and Anatolides in the Eastern Mediterranean.” The outcrop descriptions begin with Day 1 in Samos, where, atypically for the N-S stretched Aegean region, Miocene extension is E-W. The focus of Day 2 is on high-pressure assemblages in northern Samos. The following three days explore the Anatolide Belt in western Turkey, where the Menderes nappes—also known as the Menderes Massif—form the tectonic footwall below the Cycladic Blueschist Unit.

Deformation of the Lower Cambrian Sequence in the Sandikli Region (Afyon), central Turkey

The Lower Cambrian Kocayayla Group forms the stratigraphically lowermost part of the relative autochthonous Geyikdagi unit of the Taurus Range in the Sandikli (Afyon) region. It is represented by the Celiloglu Formation, Gögebakan Formation, Kestel Çayi volcanics and the Tasoluk Formation in the ascending order. The Celiloglu Formation consists of quartzites with intercalations of metapelites. The Gögebakan Formation overlies the Celiloglu Formation along a gradational boundary, and is composed of metapelites with mafic volcanic intercalations. The Gögebakan Formation grades laterally and vertically into the Kestel Çayi volcanics (Sandikli porphyroids) consisting of rhyolites with volcanosedimentary intercalations. The Tasoluk Formation is composed of yellow quartzites and it is the uppermost unit of the Kocayayla Group gradationally overlaying Kestel Çayi volcanics. The Kocayayla Group is overlain by the Sandikli unit and there is a pronounced unconformity between them. The Sandikli unit consists of white quartzites, brown dolomites, trilobite-bearing limestones and mudstones of the Middle-Upper Cambrian age. The Lower Jurassic Ilyasli Formation unconformably covers both the Kocayayla Group and Sandikli unit. The flat-laying Neogene volcanosedimentary rocks are the youngest succesion unconformably covering the all older rock units. The Kocayayla Group was deformed and underwent a low-grade metamorphism marked by sericite-chlorite-biotite/stilpnomelane-quartz paragenesis in the metapelites of the Gögebakan and Tasoluk formations and chlorite-epidote-albite-quartz and opaque assemblage in the mafic volcanic intercalations in the Gögebakan Formation, before the deposition of the trilobite-bearing Middle-Upper Cambrian succession. The Gögebakan and Tasoluk formations and the Kestel Çayi volcanics show a single penetrative foliation which mostly obliterated the primary structures whereas beds, trace fossils and cross-stratifications are partly preserved in the quarzite beds of the Celiloglu Formation. The Gögebakan Formation has rough foliation while the Kestel Çayi volcanics displays anastomizing and continuous foliation with a prominent stretching lineation. The attitude of the stretching lineation concentrates at 25/45 and 280/43 in the Kocayayla area, and s-clasts, s/c fabrics and quartz sigmoids indicate top-NNE and ESE shear sense. This difference in shear direction is related to the post-Liassic rotation in the core of southwest-verging asymmetric anticline. After removing this younger folding it is determined that, the linear fabrics has a concentration of 280/43 with top-ESE shear sense. In the Tasoluk area, the linear fabrics clusters at 320/43 with top-NW shear sense. The difference in orientation of foliation, linear fabric and shear sense in the Lower Cambrian Kocayayla Group indicate regional scale Alpine fold event(s) that rotated the earlier deformation fabrics in the Geyikdagi unit.

Kinematics of the Central Taurides during Neotethys closure and collision, the nappes in the Sultan Mountains, Turkey

In the Central Taurides, the Sultan Mountains comprise in ascending order the Çimendere unit and the Akşehir, Doğanhisar, Çay nappes composed of metasedimentary sequences deposited from Cambrian to Tertiary. The overthrust of the Çay nappe on the Lutetian Celeptaş formation representing the uppermost stratigraphic position in the Çimendere unit indicates that the latest nappe emplacement occurred during the Middle Eocene. The Oligocene and Miocene rocks are in post-tectonic facies in the west Central Taurides. The kinematic data from these nappes related to closure of the Neotethys reveal a top-NE shear sense in the northwest part and a top-SE shear sense in the southeast part of the Sultan Mountains. The Sultan Mountains are located in the north part of the Isparta Angle which was tectonically assembled by the Lycian, Hoyran–Beyşehir–Hadim and Antalya allochthons on the Bey Dağları and Anamas–Akseki autochthons from the Latest Cretaceous to the Late Pliocene. The previous paleomagnetic data showed that the west and east subsections of the Isparta Angle were subjected to post-Eocene 30°–40° anticlockwise and clockwise rotations, respectively. In consideration of these paleomagnetic data, the kinematic data measured in the Sultan Mountains might be restored into approximately E–W-trending linear fabric associated with a top-E shear sense. These new kinematic data from the nappes in the Sultan Mountains disagree with the existing tectonic models that suggest N–S nappe translation over the Central Taurides during the latest Cretaceous–Middle Eocene. The alternative tectonic model for the Antalya nappes in the core of the Isparta Angle related to east–west compression suggests westward and eastward nappe emplacements on the surrounding autochthons. However, the new kinematic data presented here point consistently to a top-E shear sense in all tectonostratigraphic units in the Sultan Mountains currently located in the north part of the Anamas–Akseki autochthon.

Field Guide to Samos and the Menderes Massif

This field-trip guide explores the tectonics of Samos and the Menderes Massif, two fascinating areas within the eastern Mediterranean section of the Tethyan orogen. The guide includes detailed outcrop descriptions, maps, and diagrams to explore along-strike variations in the Hellenide-Anatolide orogen, including the architecture of the Early Tertiary Alpine nappe stack and its strong Miocene extensional overprint. The suggested itinerary is based on the 2010 Geological Society of America Field Forum: “Significance of Along-Strike Variations for the 3-D Architecture of Orogens: The Hellenides and Anatolides in the Eastern Mediterranean.” The outcrop descriptions begin with Day 1 in Samos, where, atypically for the N-S stretched Aegean region, Miocene extension is E-W. The focus of Day 2 is on high-pressure assemblages in northern Samos. The following three days explore the Anatolide Belt in western Turkey, where the Menderes nappes—also known as the Menderes Massif—form the tectonic footwall below the Cycladic Blueschist Unit.

Palaeotethys-related sediments of the Karaburun Peninsula, western Turkey: constraints on provenance and stratigraphy from detrital zircon geochronology

Detrital zircon U–Pb geochronology of 15 Late Palaeozoic to Early Mesozoic siliciclastic sandstones from the Karaburun Peninsula in western Turkey determines maximum sedimentation ages, identifies possible source areas, and anchors the study area within the Palaeotethyan realm. Siliciclastic sandstones yielded ages from Triassic to Archean with major input from Palaeozoic to Neoproterozoic sources and very few Mesoproterozoic zircons. The youngest age groups set the new limit of the maximum depositional ages to Late Carboniferous–Early Permian for the Küçükbahçe and Dikendağı formations. Detrital zircons from Triassic sandstones are mainly Neoproterozoic and Palaeozoic in age. Zircons from the Scythian–Anisian Gerence Formation are predominantly Devonian and Carboniferous in age, while also Permian and Triassic zircon grains occur in the Carnian–Rhaetian Güvercinlik Formation. According to the zircon age populations and the data available from possible source regions, the Karaburun siliciclastic sediments, with the exception of two samples from the Dikendağı Formation, record sediment supply from units located at the southern margin of Eurasia during Late Palaeozoic and Early Mesozoic times. This interpretation is in agreement with palaeotectonic reconstructions for the closely related Greek islands of Chios and Inousses. The presence of Devonian accompanied by Carboniferous zircons in some of the Karaburun samples reveals similarities with Karakaya Complex sandstones of the Sakarya Zone in NW Turkey.

Kinematics and U-Pb zircon ages of the sole metamorphics of the Marmaris Ophiolite, Lycian Nappes, Southwest Turkey

ABSTRACT In the eastern Mediterranean, the Lycian Nappes are found in the structurally uppermost position in the Anatolide-Tauride belt related to the closure of the Neotethys. In Western Turkey, the Marmaris Ophiolite with the metamorphic sole occupies the uppermost tectonic position in the Lycian belt. The metamorphic sole is represented by discontinuous tectonic slices composed of amphibolites, phyllites, micashists and quartzo-feldspathic micaschists. Zircons from the micashists and quartzo-feldspathic micaschists display dark cores and rims. The cores yield ages between 229 and 175 Ma, inner rims yield ages between 153 and 143 Ma and the outer rims show a concordia age of 96.7 ± 0.79 Ma. In terms of their Th/U ratios, the cores and inner rims indicate igneous origin, whereas the outer rims indicate accretion during metamorphism. By dating of these zircons, the deposition time for the protolith of micaschists and quartzo-feldspathic micaschists could be constrained as the Early Cretaceous. Present-day orientation of the kinematic data from the sole metamorphics and the uppermost part of the Karabörtlen formation clearly suggest a top-to-the NE sense of shear. By taking into account the 25º–30º anticlockwise post-emplacement rotation of Southwest Turkey, it follows that the Lycian Nappes were emplaced eastward onto the Menderes Nappes. This tectonic model disagrees with the previous tectonic models suggesting northward or southward movement of the Lycian Nappes onto Menderes Nappes.