Post-paleocene deformation in Kalecik region, East of Ankara, Turkey


Thesis Type: Postgraduate

Institution Of The Thesis: Middle East Technical University, Faculty of Engineering, Department of Geological Engineering, Turkey

Approval Date: 2010

Thesis Language: English

Student: Pınar Kasımoğlu

Consultant: FUAT BORA ROJAY

Abstract:

In order to understand the tectonic evolution of the Kalecik region (Ankara, Turkey), a structural field study was performed in a selected area located in the east of Kalecik, where mostly imbricated thrust sheets of the Cretaceous Ophiolitic melange crop out. In the study area, the Cretaceous Ophiolitic melange, Cretaceous radiolaria-bearing sequences and the Paleocene units are all intruded by sub-vertical dykes. The attitudes of planar structures (dykes, beds and faults) and the kinematic data measured on faults were analyzed by using “ROCKWORKS 2002” and “Angelier Direct Inversion Method (version 5.42)” softwares, respectively. A major trend of NE-SW (045°N) direction and relatively a post-Paleocene – pre-Miocene age was determined for the dykes indicating an extension in the NW-SE direction during post-Paleocene. The dykes cut bedded units displaying a dominant set trending in WNW-ESE (297°N) direction and mostly dipping towards NE with moderate dip amounts. But at the same time, the Upper Cretaceous units were observed as intensely folded, faulted and thrusted due to the compressional regime that acted in Central Anatolia during Late Cretaceous. The angular difference between the major trend of dykes and the dominant trend of stratification was found as approximately 108°., which may also indicate that the dykes and beds were evolved during different deformation periods. The results of the kinematic analyses of different age faults revealed that the post-Paleocene – pre-Miocene Kalecik basaltic dykes are deformed under a continuous NW-SE-oriented post-Paleocene compressional to strike-slip tectonic regime which was followed by a NNW-SSE oriented post-Miocene extensional-transtensional regime.