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

Deformation fabrics in Proterozoic/Cambrian granitic rocks of the Cine napp e, and mid-Triassic granites of the Bozdag nappe constrain aspects of the t ectonometamorphic evolution of the Menderes nappes of southwest Turkey. Bas ed on intrusive contacts and structural criteria, the Proterozoic/Cambrian granitic rocks of the Cine nappe are subdivided into older orthogneisses an d younger metagranites. The deformation history of the granitic rocks docum ents two major deformation events. An early, pre-Alpine deformation event ( DPA) during amphibolite-facies metamorphism affected only the orthogneisses and produced predominantly top-to-NE shear-sense indicators associated wit h 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 Cine submassif. We refer to this Alpine deformation event as D-A3. D-A3 shear zones are associated with a N-trending stretching linea tion, which formed during greenschistfacies metamorphism. Kinematic indicat ors associated with this stretching lineation reveal a top-to-south sense o f shear. The greenschist-facies shear zones cut the amphibolite-facies stru ctures in the orthogneisses. Pb-207/Pb-206 dating of magmatic zircons from a metagranite, which crosscuts orthogneiss containing amphibolite-facies to p-to-NE shear-sense indicators, shows that D-PA occurred before 547.2 +/-1. 0 Ma. Such an age is corroborated by the observation that mid-Triassic gran ites of the Cine and Bozdag nappes lack D-PA structures. The younger, top-t o-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 th e Eocene.