Authors: BORA ROJAY, A. KARACA
Abstract: Central Anatolia, located on the immense Alpine-Himalayan orogenic belt, has a complicated neotectonic evolution, and NE-SW-trending Neogene horsts-graben systems that rejuvenate pre-existing palaeostructures are among the most important structures which help us understand the tectonic evolution of Central Anatolia. Post-Miocene deformational studies were carried out in Miocene-Quaternary sequences situated at the southeastern margin of the Galatean Volcanic Province (NW of Central Anatolia, Turkey) in order to understand the deformational history of Central Anatolia. The structural analyses were based on bedding attitude data and fault plane slip data. Fold analysis in Miocene units gave an asymmetrical fold axis trending 046ºN. Although there is a clear angular unconformity between the Upper Miocene and Plio-Quaternary sequences, similar fold analysis in the Plio-Quaternary clastics revealed a symmetrical open fold attitude trending 040ºN, thus indicating an almost identical trend for all the post-Miocene folds. Stress analyses were performed by processing fault plane slip lineation data, using the Angelier Inversion Method. In the analyses, no reliable results could be obtained for the post-Miocene-pre-Pliocene compressional period. But the results of the post-Plio-Quaternary period strongly revealed a continuous extension from NW-SE to NNE-SSW directions since the Pliocene. Stress analyses together with the field observations showed that the area has evolved structurally in several phases of deformation since the Late Miocene. The NW-SE-directed post-Miocene compression, based on fold analysis and field observations, was followed by a regional NW-SE to NNE-SSW multi-directed extension, based on slip-data analyses, operating since the Pliocene.
Keywords: palaeostress analysis, extensional tectonics, neotectonics, Late Miocene-Plio-Quaternary, Anatolia
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