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

Citation
K. Gessner et al., Tectonic significance of deformation patterns in granitoid rocks of the Menderes nappes, Anatolide belt, southwest Turkey, INT J E SCI, 89(4), 2001, pp. 766-780
Citations number
59
Language
INGLESE
art.tipo
Article
Categorie Soggetti
Earth Sciences
Journal title
INTERNATIONAL JOURNAL OF EARTH SCIENCES
ISSN journal
1437-3254 → ACNP
Volume
89
Issue
4
Year of publication
2001
Pages
766 - 780
Database
ISI
SICI code
1437-3254(200104)89:4<766:TSODPI>2.0.ZU;2-S
Abstract
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.