Cenozoic pure-shear collapse of the southern Menderes Massif, Turkey
Lindsay J. Iredale, Christian Teyssier, Donna L. Whitney, 2013. "Cenozoic pure-shear collapse of the southern Menderes Massif, Turkey", Geological Development of Anatolia and the Easternmost Mediterranean Region, A. H. F. Robertson, O. Parlak, U. C. Ünlügenç
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A transition from construction to collapse of the Alpine orogen in Middle to Late Eocene time is recorded in the structural fabrics of gneissic rocks in the southern Menderes Massif, western Turkey. Augen gneiss in the southern Menderes Massif indicates a spatial switch of shear sense along a north–south section through the complex (top-to-north shear in the north and top-to-south in the south). This ‘kinematic hinge’ corresponds to a broad zone of dominant pure shear where crust underwent vertical thinning and approximate north–south extension. During this extension, foliation became corrugated with fold axes parallel to lineation, indicating inflow from neighbouring crust to the east and the west. Published geochronologic work suggests a Middle to Late Eocene age for this dominant fabric. Thermal weakening of felsic Menderes crust beneath Alpine nappes may have triggered this orogenic collapse. Deformation fabrics developed at temperatures of c. 550 °C, and progressive cooling during collapse generated strain localization within a kilometre-thick shear zone at the southern margin of the Menderes Massif. In the southern Menderes, the corrugation of foliation indicates that Middle to Late Eocene flow was constricted into an orogen-perpendicular direction. This behaviour is similar to the collapse and orogen-parallel extension of the European Alps (Lepontine dome, Tauern Window).
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Geological Development of Anatolia and the Easternmost Mediterranean Region
Anatolia and the easternmost Mediterranean region, especially Turkey, Cyprus and northern Syria, represent an excellent natural laboratory for the study of fundamental geological processes (e.g. rifting, seafloor spreading, ophiolite genesis and emplacement, subduction, exhumation and collision). Their interaction has created an intriguing array of deep-sea basins, microcontinents and suture zones.
The volume’s 22 papers include a large amount of new field-based information (much of it multidisciplinary and the product of teamwork). After an overview, the volume is divided into four sections: Late Palaeozoic–Early Cenozoic of the Pontides (northern Turkey); Late Palaeozoic–Early Cenozoic of the Taurides–Anatolides (central and southern Turkey); Late Cretaceous–Pliocene sedimentary basins and structural development (central Anatolia to the Mediterranean); Late Miocene–Recent Neotectonics (southern Turkey, Cyprus and northern Syria).
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