Abstract

In the Çamardı (Niğde) district, the Niğde Massif is composed of marbles, gneisses, quartzites and amphibolites. These rocks of the Massif have been cut by Cretaceous aged granodiorites. The Paleocene-Eocene aged low-grade metamorphic rocks constitute the autochthonous cover of the Massif. These units are tectonically overlain by the Upper Cretaceous-Paleocene aged flyschoid and island arc type rocks. The Oligocene-Quaternary aged terrestrial and volcanic rocks constitute the youngest units of the district. The metamorphites of the Niğde Massif have been subjected to at least four phase ductile deformation (D1, D2, D3, and D4) and folding. Through the D1 phase deformation, the rocks of the Massif have been folded as recumbent-isoclinal folds (F1-F2 phase folding) and have gained a structure with a foliation (S1) which is parallel to the axial planes. Owing to the isoclinal and intense folding of the bedding planes (S0) of the rocks, bedding transposition have developed and transposed folding structures have formed. Through the D2 phase deformation, northeast-southwest trending and both northeast and southwest dipping map scale folds (F3 phase folding) have developed. As a result of the interference of F1-F2 and F3 phase folds, in the district, folds, generated by Type-2 folding, have formed (mushroom folds). Second phase mesoscopic folds are of tight-isoclinal geometry and display asymmetrical and inclined fold feature. In the study area, as a result of D3 phase folding a large dome structure has developed in the district. And D4 phase folds have formed map scale synformal and antiformal structures that are trending approximately perpendicular to D2 phase, plunging southeast and trending northwest-southeast. Through D4 phase deformation, the cover rocks have been deformed together with the basement rocks (F5 phase) that they overlie. The microscopic observations show that Cretaceous-Eocene aged rocks have been subjected to low-grade metamorphism in the greenschist facies through D4 phase deformation. The geometry of the F5 phase folds reflects cuspate-lobate structure which is the folding type peculiar to the districts where basement rocks and cover rocks have been deformed together.

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